Setup

El Niño got its official upgrade from Watch to Advisory status back on June 11, so this isn’t a forecast anymore in the sense that conditions are already observed, actively strengthening, in the tropical Pacific. The signal is showing up clearly in the Niño 3.4 region (the patch of central and eastern tropical Pacific ocean meteorologists watch to classify ENSO events). The mid August IRI multi model plume has 25 of 26 participating models placing Niño 3.4 in the very strong category for October through December, and 15 of those models forecast anomalies reaching or exceeding 3.0 degrees C, which is beyond the top of the standard intensity scale entirely. That’s an unusually tight cluster of agreement for a seasonal forecast this far out.

Timing

Peak intensity is expected between October and December, with strong to moderate conditions likely persisting into March 2027 based on current guidance. That gives a wide window where the atmospheric effects stay in play, not just a single sharp peak.

Global threats

A very strong El Niño loads extra heat and water vapor into the atmosphere globally and reroutes storm tracks through teleconnections (the atmospheric links between tropical Pacific heat and weather patterns thousands of miles away). Combined with the ongoing background warming trend, that raises the odds of record global temperatures through the rest of 2026 and into 2027, along with the usual El Niño pattern of drought in some regions paired with flooding in others.

The California angle

This is where the California Institute for Water Resources briefing, from climatologist Daniel Swain, gets specific. Expect warmer near shore water and higher coastal humidity, raising both marine ecosystem stress and late summer and autumn heat risk along the coast. Higher sea levels and stronger wave action raise the odds of coastal inundation and erosion, particularly when El Niño coincides with king tides. And a shifted winter storm track tilts the odds toward above average seasonal precipitation for central and southern California, which raises inland flood risk on rivers, creeks, and streams.

Confidence and what could still move

Split this into two separate questions. Pattern confidence, meaning will El Niño itself become historically strong, is high. Placement confidence, meaning exactly how much rain falls where in California this winter, is lower. Strong El Niño winters tilt the odds toward wet, they don’t guarantee it, and consequential flooding can happen in California in any winter regardless of ENSO phase. Watch for CPC’s next long lead seasonal outlook, issued August 20, for the first update built on the higher probability numbers.

Synoptic setup

The numbers back up the strengthening trend. NOAA’s July readings had the Niño 3.4 region (the benchmark index) at +1.4°C, Niño 3 at +1.7°C, and Niño 1+2, the patch closest to South America, at +2.9°C, the warmest of the three. Below the surface, the story is just as loud. The subsurface warm pool, the reservoir of heat sitting beneath the surface, is running anomalies up to +10°C at depth, reflecting a deeper-than-average thermocline (the boundary between warm surface water and the cold water underneath). That deep reservoir is still working its way toward the surface, which is why forecasters expect continued strengthening rather than a plateau.

The atmosphere is responding in kind. Low-level winds are blowing from the west instead of the usual easterly trade winds, upper-level winds are doing the opposite, and rainfall has shifted east toward the central Pacific while drying out over Indonesia. The Southern Oscillation Index, a measure of the pressure seesaw between Darwin and Tahiti that tracks the atmospheric side of ENSO, ran close to two standard deviations negative in July. Ocean and atmosphere are both telling the same story right now.

Worth noting in the background: this event is developing on top of a global baseline that’s running roughly 1.3°C warmer than pre-industrial. That doesn’t change the ENSO signal itself, but it does mean the atmosphere has more moisture available to work with when these storm systems come through.

Timing

NOAA upgraded to an El Niño Advisory on June 11, up from a Watch. The Climate Prediction Center updates its diagnostic discussion monthly, and the most recent one, issued August 13, kept the greater-than-90-percent call for a very strong event this fall and winter. The next one is due September 10. Peak strength is expected in the October-December to November-January window, which is standard timing for these events. CPC’s official seasonal outlook, last issued July 16, is due for an update August 20. That update will be the first full seasonal package built around this month’s strength upgrade, so it’s worth watching closely.

What this means for the Southeast

CPC’s most recent seasonal outlook favors above-normal precipitation across the southern tier, with the highest probabilities specifically over parts of the Southeast. Winter is when El Niño’s teleconnections, the long-distance links between Pacific ocean temperatures and weather patterns thousands of miles away, run strongest, and the mechanism is straightforward. The subtropical jet strengthens and stretches farther east, turning into a corridor that carries Pacific and Gulf moisture across Texas, the Gulf Coast, and into Florida and up the Southeast seaboard, storm system after storm system.

The last two strong events showed exactly this pattern. In 1997-98, the winter came in the second warmest and seventh wettest nationally since 1895. Florida’s dry season rainfall nearly doubled its normal total, the northern Gulf Coast, including southern Alabama and Georgia, ran 10 to 30 percent above normal, and the Carolinas saw some of the highest river crests ever recorded on the Cape Fear. In 2015-16, above-normal rainfall covered most of the Southeast again, with repeated severe weather episodes along the Gulf Coast in January and February.

The winter severe weather threat

This is the part of the pattern that deserves the most respect. A strengthened subtropical jet overhead, combined with Gulf of Mexico water that stays warm into winter, builds the wind shear (winds changing speed and direction with height) that storms need to rotate, layered on top of warm, moist, unstable air at the surface. That combination has produced some of Florida’s worst tornado outbreaks on record. The February 1998 central Florida outbreak remains the state’s deadliest, and it happened at night, at the peak of the last comparable El Niño. A weaker El Niño in February 2007 produced another deadly nighttime outbreak.

The other extreme strong El Niño on the books, 1982-83, tells the same story. On February 1-2, 1983, a jet streak (a pocket of especially fast wind embedded in the jet stream) clocking around 180 mph over the central Gulf drove a line of severe thunderstorms across the entire state of Florida, Panhandle to Keys, in about a day and a half. At least 21 tornadoes touched down, and roughly 200 people were left homeless. NWS Melbourne’s own research on Florida’s dry-season tornado climatology ranks 1982-83 and 1997-98 as the two most extreme El Niño-driven tornado seasons in the state’s history, with 1982-83 actually producing the higher count of strong and violent tornadoes of the two. Nighttime winter tornadoes along the Gulf Coast and across Florida are the specific hazard to plan around this season, precisely because they’re the hardest to see coming and the hardest to wake up for.

The ice storm and snow risk

Most people hear “wet El Niño winter” and think rain, and for the Southeast that is usually the safer bet. Moist air riding the strengthened subtropical jet tends to arrive faster than any cold air can settle in behind it, so a lot of what falls is heavy rain rather than anything wintry. But “usually” is doing a lot of work in that sentence. The history of strong El Niño winters in the Southeast includes some serious snow and ice events, and this winter carries a specific reason to take that history seriously.

Atlanta’s National Weather Service office once reviewed the five strongest El Niño winters on record dating back to 1950, and the wintry precipitation history came back genuinely mixed. The winter of 1972-73, itself a strong El Niño, delivered the snowiest winter on record for Columbus and Macon, Georgia. Atlanta missed that snow but got hit instead by a crippling ice storm in early January. March 1983, near the tail end of another strong event, brought a late-season heavy snow to the region. None of that was the outcome in every strong El Niño winter, but it happened often enough that NWS forecasters describe the range of possible outcomes as genuinely open: an ice storm, a snow event, major flooding, or a severe weather outbreak have all shown up in different strong El Niño years, sometimes more than one in the same season.

The mechanism is the same setup that produces the region’s classic ice storms in any winter, just with more fuel behind it. Cold air damming, known locally as “the wedge,” is a shallow pool of cold air that gets pinned against the eastern side of the Appalachians and refuses to budge. When Gulf moisture riding the active jet arrives on top of one of these wedges, the warm, wet air rides up and over the cold air instead of scouring it out, and the result is freezing rain rather than plain rain, often across the Piedmont of Georgia and the Carolinas, a part of the Southeast that does not typically deal with ice.

There is a newer wrinkle specific to this winter. Long-range forecasters are flagging early signs of a weaker or disrupted stratospheric polar vortex, the pool of frigid air that normally stays locked up over the Arctic, for January and February 2027. A disrupted vortex does not guarantee Arctic air reaches the Southeast, but it does raise the odds that it becomes available. The real risk this winter is not a uniformly cold season. It’s the chance that a stretch of genuine Arctic air breaks loose right as an unusually active, moisture-rich subtropical jet is running overhead. Cold air from the north meeting Gulf moisture from the south is exactly the recipe for a significant winter event rather than another round of plain rain. It’s also the same setup, on a larger scale, blamed for East Asia’s severe cold snap during the 2015-16 super El Niño, so the physical link between a very strong event and a wobbling polar vortex has precedent.

None of this is locked in. A single storm system can’t be pinned on El Niño alone, and the polar vortex signal is still an early one that could fade well before January. But heading into this winter with only a “wet and mild” expectation for the Southeast would miss real history. The ice storm and snow risk should be treated as elevated above a typical winter, not as background noise.

Temperature: the less certain half

The precipitation signal is one of the cleaner calls in this outlook. Temperature is messier. CPC’s most recent seasonal package leans above-normal temperatures for much of the West, the northern tier, and parts of the East, but the signal weakens considerably across the Southwest, the southern Plains, the Lower Mississippi Valley, and the Southeast, where several areas sit at equal chances among above, near, and below normal. Historically, strong El Niño winters have tended to run a touch cooler than normal along the immediate Gulf Coast even as the rest of the country warms, though that tendency fades across the Carolinas. The takeaway: don’t assume a mild winter everywhere just because El Niño usually gets filed under “warm.” Periods of below-normal cold can still show up in the Southeast even if the three-month average doesn’t finish there.

The “strongest on record” question

NOAA hasn’t declared this the strongest El Niño on record. What its forecasters have said, as of August 13, is that there’s a 69 percent chance the October-December Niño 3.4 average clears the threshold (+2.5°C on the relative Niño index) that would put it ahead of every event dating back to 1950, including 1997-98 and 2015-16, the two strongest on the books. That’s meaningfully more likely than not, but it’s still a probability, not a done deal.

It’s also worth remembering that strength sets the odds, not the outcome. CPC’s own discussion is direct about this: a stronger event raises the chances of experiencing El Niño’s typical impacts, but doesn’t guarantee them. The clearest example is 2015-16 itself. Its peak Niño 3.4 values were comparable to 1997-98, but California ended up drier than expected that year because the storm track ran farther north than the textbook pattern called for. A record-strength Pacific improves the Southeast’s odds of a wet, active winter. It does not lock in any single storm, flood, or outbreak.

Confidence and what could change

Pattern confidence is high. Better than 90 percent for a very strong event, and the precipitation tilt toward the Southeast is one of the more reliable signals in the entire outlook. What’s still moving is the finer detail: whether this becomes the outright strongest event on record (69 percent versus 31 percent right now), the exact timing and placement of individual storm systems and any severe weather outbreaks, and the temperature side of the forecast for the immediate Gulf Coast. Watch the weekly Niño 3.4 anomaly through early autumn. Sustained readings above 1.5°C would further support the very-strong path. Also watch the stratospheric polar vortex signal as we get into December and January. That’s the piece that determines whether this winter’s storm systems mostly bring rain or start delivering real ice and snow to the Southeast. CPC’s updated seasonal outlook lands August 20, and the next full ENSO Diagnostic Discussion is September 10. I’ll have updates after both.

Synoptic setup: A substantial shortwave trough currently sitting over southern Manitoba is amplifying and sliding southeast toward the Lake Superior vicinity through tonight. Riding with it is a strengthening belt of west-northwesterly flow aloft, 50 to 70 knots at mid levels and a genuinely impressive 100 knots in the upper levels over Minnesota and Wisconsin. Ahead of that trough, a plume of steep mid-level lapse rates is advecting east-southeast into a warm sector holding dewpoints from the upper 60s into the lower and middle 70s. That combination of strong deep-layer shear and real instability is the setup that turns ordinary thunderstorms into supercells.

Timing: Early day storms are possible this morning across southeast Minnesota into western Wisconsin and eastern Iowa, riding elevated instability with effective shear over 50 knots, capable of hail and some strong gusts. That activity should wane through the day, opening a possible lull before more organized development kicks off by late afternoon along the cold front as it tracks toward Wisconsin, Upper Michigan, and northern and eastern Iowa. Storms should evolve into clusters through the evening, with the damaging wind and tornado threat persisting southeastward before intensity finally fades overnight.

Threats and storm mode: Initial cells today should be dominated by supercells given the strength of the deep-layer shear, with a corridor of large hail and tornado risk running east of the instability axis, from Iowa across Wisconsin into Upper Michigan. As the evening progresses, expect transition toward clusters, at which point the wind threat becomes more widespread even as some tornado risk lingers.

The strong-tornado question: This is the part worth slowing down for. Effective storm-relative helicity, a measure of the spin available to a storm’s inflow, may exceed 300 square meters per second squared across Wisconsin into Upper Michigan, supported by seasonally very strong winds in the 2 to 3 kilometer layer above ground (700 mb winds over 50 knots). That’s the kind of low-level spin that lets a supercell tighten and produce a strong, potentially long-track tornado rather than a brief spin-up. Forecasters note tornado probabilities could still be raised in later updates once this morning’s convective debris and its effect on afternoon heating gets resolved. Near-surface winds may veer some with time, which would work against the tornado threat, but the SRH numbers involved are high enough that the strong-tornado potential looks real regardless.

Elsewhere today, the Carolinas and far southern Virginia sit under a slight risk this afternoon as a moist airmass destabilizes south of a west-east front. MLCAPE over 2000 J/kg and precipitable water above 2 inches, paired with modest westerly flow aloft, points toward multicellular storms and isolated damaging gusts through sunset. And offshore, Tropical Depression Two is expected to gradually strengthen over the northeastern Gulf today and tonight, though current guidance keeps supercell-related tornado potential low given the system’s overall weakness and light winds aloft.

Confidence and what could change: Pattern confidence for today is high, this setup produces severe weather. Placement confidence within the Iowa to Upper Michigan corridor is good but not locked, and the biggest lever to watch is how much early morning convection and its cloud debris limit afternoon heating. Less heating means less instability to work with, which could shift or shrink the tornado corridor. Watch for SPC to adjust tornado probabilities through the day as that resolves.

For Tuesday, I’m working from Saturday’s medium range guidance rather than a fresh Day 2 outlook, so treat this as a lower confidence read. That guidance has an upper trough pivoting across the Ohio Valley into the Mid-Atlantic Tuesday and Wednesday, with a surface cold front sweeping through by Wednesday night.

Convection may already be ongoing Tuesday morning across Illinois, Indiana, lower Michigan, and western Ohio, and the downstream airmass looks favorable for scattered severe storms Tuesday afternoon and evening, likely organized into one or more line segments ahead of the front. Damaging wind is the pattern-suggested headline threat. I’ll have a sharper read once SPC’s actual Day 2 product updates.

Synoptic setup

The depression is caught in a weak steering environment, wedged between a ridge over the western Atlantic, another ridge building over the south-central and southwestern U.S., and a trough digging into the Northeast. None of those features currently has a strong enough grip on the system to move it with any real speed, which is why it sat still today and even nudged southeast. That changes as the U.S. ridge strengthens and takes over as the dominant steering influence by Tuesday, setting up the west and west-northwest turn.

Working against organization right now: dry air intruding from the northeast, and northeasterly vertical wind shear (upper-level winds that tilt a storm’s structure and disrupt strengthening). The circulation itself is also large and somewhat diffuse, with shower activity spread across much of the eastern Gulf rather than tightly wrapped near the center. Recon and ASCAT data both put peak winds around 25 knots as of the afternoon advisory.

Timing

Monday: the system reaches tropical storm strength, and outer bands could bring tropical storm conditions to the Florida Panhandle late in the day. Tuesday: the west/west-northwest turn takes hold as the U.S. ridge builds east. Wednesday through Thursday: track continues along or just offshore of the northern Gulf Coast, with shear potentially relaxing midweek, which matters a lot for how strong this gets (more on that below). By day five, guidance brings the system near the upper Texas coast before it weakens inland.

The intensity question

This is the real story with TD Two. NHC’s official forecast brings it to 60 mph by 72 hours, roughly strong tropical storm strength, but the agency is explicit that this is a low-confidence call. Model guidance spans an unusually wide range: some solutions keep this a tropical depression the entire time, others spin it up to hurricane strength. The official forecast splits the difference and leans toward the stronger end of that spread, but the deciding factor is something models struggle with, how much time the center spends interacting with land versus staying over that 85 to 86 degree Gulf water. More time over open water and less shear midweek both favor stronger. More land interaction caps it. Nobody has high confidence in that balance yet.

Threats and impacts

Flash flooding is the widest-reaching threat, possible through Thursday from western Florida into southern Alabama, Mississippi, and Louisiana, largely independent of how strong the wind field ends up. Storm surge is forecast for the Florida Panhandle specifically, 1 to 3 feet of inundation from Indian Pass to Chassahowitzka if peak surge coincides with high tide. Wind impacts scale directly with the intensity uncertainty above, but even a weak tropical storm moving slowly along the coast can produce a prolonged wind and rain event.

Confidence and what could change

Pattern confidence is solid: this becomes a tropical storm Monday, and the west turn Tuesday is well supported by the ridge building over the U.S. Placement confidence along the coast late week is lower, since the track still depends on exactly how that ridge sets up. Intensity confidence is the lowest of the three, watch for updates on shear relaxing midweek and how close to the coast the center tracks, since either one could shift this meaningfully in either direction.

A strong upper-level ridge, a textbook heat dome, has taken over the eastern half of the country and holds through at least Thursday. Somewhere around 230 million people sit under dangerous heat, with heat index values of 105 to 110 across a wide swath from the Midwest to the Mid-Atlantic. The headline is not really the afternoon high. It is the combination of relentless daytime heat, oppressive humidity, and overnight lows that refuse to drop, several days in a row.

The Synoptic Setup

This is a dipole pattern, two opposite features working as a pair. A deep trough (a southward plunge in the jet stream) has dug into the Pacific Northwest and the West, dropping temperatures there and, unfortunately, ramping fire weather back up across Utah, Colorado, and Arizona as winds pick up. Downstream, the flow amplifies into a tall ridge of high pressure over the eastern US. Mid-level heights are building into the 594 to 596 decameter range, which is a very strong ridge for this part of the country.

The ridge is the engine. Beneath it, the air subsides, meaning it sinks. Sinking air warms adiabatically (it heats up simply from being compressed as it descends), it caps off cloud development, and it leaves the surface exposed to full late-June insolation with the longest days of the year doing the rest. The anticyclonic flow around the ridge also chokes off some of the deep Gulf moisture transport, which is why a few areas closer to the Appalachians may trend toward a drier heat. For most of the footprint, though, low-level moisture is plenty high, and that is what drives the heat index well above the air temperature.

Timing and the Westward Drift

The dome’s eastern flank pushed into the Midwest and Great Lakes Monday and Tuesday, with Chicago and the Ohio Valley seeing heat index values near 110. The Northeast loads up Tuesday into Thursday, with Washington, Philadelphia, and Richmond in the mid to upper 90s and the feels-like climbing to 100 to 110. Some forecasts put Philadelphia near the century mark on multiple days and Washington at or above 100 for as many as four. Late this week the ridge axis retrogrades, drifting back toward St. Louis and then toward the Four Corners into next week. That retrogression is what eventually opens the door for relief in the East, New England first, the Mid-Atlantic last.

Why the Overnight Lows are the Story

The National Blend of Models is signaling widespread record high minimum temperatures across much of the eastern US, with lows only sinking to the mid or upper 70s and the big-city heat islands holding near or above 80. Pavement, brick, and concrete soak up solar energy all day and bleed it back out after dark, and the long July-adjacent nights are too short to flush it. Physiologically, this is the dangerous part. The human body relies on the overnight dip to recover. Remove that recovery window for three, four, five nights running and core heat load accumulates, which is the mechanism behind most heat-related deaths. This is why heat is the deadliest weather hazard in the country in an average year, and it does it quietly.

Confidence and What Could Change

Pattern confidence is high. The ridge is real, it is strong, and the multi-day heat is locked in. The lower-confidence piece is the timing of the breakdown. Models agree the dome retrogrades west toward the holiday weekend, but exactly when each city crosses back to the cool side is still in play. Boston may turn the corner before the Fourth. Washington may not get there until late on the Fourth or into Sunday. The other lever is the ring-of-fire convection riding the periphery of the ridge, storm complexes tracking from the northern Plains into the Great Lakes and Northeast, plus Gulf Coast storms. Where those clusters hit, they can shave a few degrees off an afternoon, but they are hit-or-miss and not a reliable break.

One bit of context worth keeping honest: this is happening at the same time Europe sits under its own heat dome, a blocking pattern that has been breaking June records from Spain to the UK. Two major heat domes on both sides of the Atlantic in the same week is unusual, and the long-term trend toward more frequent and more intense heat is well established in the data.

For now, treat the nights as seriously as the afternoons, check on the people who do not handle heat well, and find your cooling option before you need it.

The Overall Picture

The Storm Prediction Center carries a Moderate Risk (category 4 of 5) from central Illinois into northwest Indiana, with a 15% hatched tornado probability. Hatched means a 10% or greater chance of EF2 to EF5 tornadoes within 25 miles of any point inside it, which is the language SPC reserves for days with real strong-tornado potential. The outlook is explicit: an outbreak of severe storms is expected, with intense tornadoes, damaging gusts to 80 mph, and hail to 2.5 inches. A second, lower-end corridor runs along the cold front from southeast Kansas into Missouri.

The Synoptic Setup

A strong mid-level jet streak (a core of fast winds aloft) overspreads the Midwest and lower Great Lakes today. A deep surface low over the Upper Midwest tracks toward the lower Great Lakes and into Ontario and Quebec through the period. Ahead of the trailing cold front, a strong low-level jet advects rich Gulf moisture northward, and a warm front, reinforced by this morning’s convection, lifts into central and northern Illinois and northern Indiana. The wind fields here are potent for mid-June. The Day 1 reasoning notes roughly 70 knots of mid-level flow, 100-plus knots at upper levels, and a 60-plus knot low-level jet. That combination of deep-layer shear and strong low-level shear is the kinematic backbone of the strong-tornado threat.

Timing

Convection is already ongoing this morning across eastern Iowa, riding the nose of the low-level jet. That cluster shifts east-southeast through northern and central Illinois into Indiana and carries a damaging-wind threat, but it begins in a drier, less unstable airmass with eastward extent and most likely weakens through mid to late morning. The more substantial threat develops by early to mid afternoon and depends heavily on how that morning activity evolves. Given the strength of the moisture advection, expect relatively rapid airmass recovery from the Quad Cities vicinity into central Illinois. Storms forming near the surface low and warm front in that window should be discrete and tap into strong low-level shear. The threat then continues eastward into Indiana through the evening, with low-level moisture improving with time, which means it does not end at sunset.

Threats and storm mode

Mode is the whole story today. Discrete supercells near the warm front are the primary tornado concern, with large to very large hail, significant wind gusts, and strong to intense tornadoes all possible in the same storms. As activity congeals and pushes into Indiana overnight, expect a transition toward a more linear, damaging-wind-dominant structure, though embedded rotation and a tornado or two remain possible in that phase. Along the cold front from southeast Kansas into Missouri, storms should be supercellular for a few hours before the effective shear vectors, which have a large component oriented along the front, encourage upscale growth. Steep mid-level and low-level lapse rates there favor large to very large hail and 75-plus mph gusts, and despite sitting west of the low-level jet core, the low-level wind fields still support a tornado risk, some potentially strong.

The strong-tornado threat

This is the part worth slowing down on. The ingredients that produce significant tornadoes are stacking in the same place this afternoon: rich boundary-layer moisture pooling along a lifting warm front, strong storm-relative helicity (a measure of the spin available to a storm’s inflow) inside that 60-plus knot low-level jet, and a setup that favors discrete cells rather than a quick line. Discrete supercells in a high-shear, moisture-rich warm-frontal environment are the classic recipe for strong, long-track tornadoes. The hatched 15% is SPC telling you the EF2-plus potential is not hypothetical today.

Confidence and what could change

Pattern confidence is high. The jet structure, the surface low, and the moisture return are locked in, and the broad footprint of a significant severe day is not in question. Placement confidence on the discrete tornado threat is lower and tied to one lever: how cleanly this morning’s convection exits and how much the airmass recovers behind it. If the morning storms scour out the warm sector or leave widespread cloud cover, the afternoon underperforms. If the sun comes out behind them across central Illinois, that is where the most dangerous storms go up. Watch the warm front position and the clearing line through midday. That is your tell.

If you are in the risk area, today is a day to have multiple ways to receive warnings, especially ones that will wake you tonight, and to know your safe place before a warning arrives.

Wednesday brings an all-hazards severe event to the Middle Mississippi Valley, Indiana, and western Ohio. SPC moderate risk for severe weather with a broader enhanced risk. Strong tornadoes, very large hail, and swaths of damaging wind are all realistic. The headline question is storm mode, and the morning convection holds the answer.

Synoptic setup

A strong mid-level jet stretches from the Northwest into the Ohio Valley, with an embedded 75 to 85 knot shortwave trough swinging from Nebraska into Iowa by Wednesday afternoon. A strong surface cyclone tracks from eastern South Dakota toward southern Ontario through the period, dragging a cold front east and lifting a warm front north across the Midwest.

The kinematics are the story. Forecast soundings show 70 knots of mid-level flow, 100 plus knots of upper-level flow, and a 60 plus knot low-level jet (the ribbon of strong winds just above the surface that feeds moisture and spin into the warm sector). That combination produces more than enough deep-layer and low-level shear for rotating storms. Pair it with the instability building ahead of the front and you have a high-end kinematic environment waiting on storms to use it.

Timing

Elevated supercells should be ongoing at the start of the period across central and eastern Iowa, riding the nose of the low-level jet along and north of the warm front. These carry a hail threat through the morning and a tornado threat on their southern edge if any storm can anchor to the boundary. As that activity shifts east-southeast, strong low-level flow drives rapid destabilization in its wake across central and northern Illinois. The afternoon and evening are when the environment is most dangerous. Widespread development is expected along the cold front by late afternoon from southeast Iowa to far eastern Kansas, then east through the evening.

Threats and storm mode

Mode drives everything here. Storm motions are fast, on the order of 40 to 50 knots, with a Bunkers right-mover (the expected path of a rotating supercell) oriented nearly perpendicular to the front. That orientation argues some storms can hold discrete supercell structure rather than congealing into a line. If they do, the evening tornado threat runs highest from north-central Missouri into central Illinois. If strong forcing wins out and storms grow upscale early into a bowing line (a line of storms that produces widespread wind damage), the tornado and hail threats ease while the significant-wind threat climbs.

The strong-tornado threat

Where a supercell can latch onto the warm front or trailing outflow boundary, the ingredients line up for strong tornadoes. The low-level jet keeps streaming, isentropic ascent (warm air gliding up over the frontal surface) keeps generating new development along the boundary, and storm-relative helicity (a measure of the spin available to a storm’s inflow) is more than sufficient under that 60 plus knot low-level jet. The limiting factor is not the environment. It is whether the morning storms leave a clean enough warm sector for discrete cells to mature in it.

Confidence and Uncertainty

Pattern confidence is high. This is a genuinely favorable severe setup and it is not going away. Placement confidence is lower, and it hinges on one lever: the morning convection. How far north the warm front lifts, how quickly the air recovers behind the early storms, and whether the warm-frontal development stays narrow or spreads out will decide exactly where the sharpest tornado corridor sets up. Watch the Day 1 outlook and the morning mesoscale discussions for that refinement. The 45 percent core could shift, and an upgrade is not out of the question if guidance converges on a clean recovery.

There is also a separate Marginal Risk along the Gulf Coast as a tropical airmass moves inland ahead of a disturbance NHC is tracking. That is a low-end, localized threat, not part of the Midwest story, but worth a glance if you are on the coast.

Wednesday, June 17 is the day to circle. A potent upper-level disturbance, strong by mid-June standards, overspreads the Midwest as a warm front lifts north through the Mississippi and Ohio Valleys. The environment supports supercells capable of all severe hazards, with the greatest risk for significant severe storms across the Lower Missouri and Mid-Mississippi Valleys, and a strong-tornado threat that hinges on where the warm front settles.

Synoptic setup

An upper shortwave trough deepens as it tracks across the Upper Midwest and Great Lakes on Wednesday, and an intense 500 mb jet streak, more than 80 knots and notable for June, overspreads the region by evening. That is the engine. A jet streak that strong this late in the season is the headline, because it provides both the large-scale lift and the deep-layer shear to organize and sustain storms.

Beneath it, the low levels are equally impressive. A daytime 850 mb low-level jet of 40 to 50 knots develops by mid to late afternoon. At the surface, a low deepens and moves across the Upper Mississippi Valley and Lower Michigan, with a warm front lifting rapidly north across Illinois and parts of the Ohio Valley through 00Z, and a trailing cold front pushing east behind it. The warm sector fills with mid 60s to low 70s dewpoints and strong destabilization. So you have the classic warm-sector recipe: rich low-level moisture, steepening lapse rates aloft, and a kinematic profile (the wind structure) more than capable of rotating updrafts.

Timing

Convective initiation looks like Wednesday afternoon in the warm sector. The early window is the discrete phase, when semi-isolated supercells can mature in a relatively uncontaminated environment. As the low-level jet strengthens through the evening, upscale growth into a bowing MCS becomes likely, transitioning the dominant hazard from tornadoes and very large hail toward a broad damaging-wind signal. The deep-layer flow is intense enough that severe weather persists into the overnight across the Ohio Valley rather than collapsing after sunset. That overnight continuation is a real concern for the eastern half of the threat area.

Threats and storm mode

Mode is the whole story on a day like this. In the afternoon discrete phase, expect supercells carrying a tornado and very large hail threat. All severe hazards appear likely, and the Lower Missouri and Mid-Mississippi Valley corridor is where the significant (the SPC’s term for the most intense) severe potential concentrates. Once storms congeal into a line, the threat broadens spatially but shifts toward wind, with embedded circulations still capable of brief tornadoes within the line.

The strong-tornado threat

This is the part worth slowing down on. The ingredients for strong tornadoes, meaning EF2 and up, are the overlap of strong instability, strong deep-layer shear, and enlarged low-level shear and storm-relative helicity (a measure of the streamwise spin available to an updraft’s inflow). The first two are well supported by the 80-knot jet aloft and the 40 to 50 knot low-level jet. The third, the low-level component, maximizes right along and just north of that lifting warm front, where surface winds back and the hodograph (the curve that describes how wind turns with height) grows. If the warm front lifts as modeled and the open warm sector destabilizes during peak heating, the afternoon discrete window is when a couple of supercells could produce strong, potentially significant tornadoes before linear upscale growth takes over.

The honest caveat: this threat is conditional on placement. The track of the surface low and the orientation of the jet streak over the developing warm sector are still being resolved, and the risk areas will likely shift in subsequent outlooks. A warm front that lifts faster or slower than progged would move the highest tornado corridor with it. That uncertainty is normal at this range and does not lower the ceiling, it just blurs the exact bullseye.

Confidence and what could change

Pattern confidence is high. The ECMWF and GFS agree on the strong jet and the overall evolution, which is why this day stands out in the medium range while the days around it carry lower predictability. Placement confidence is moderate, limited by the warm front position and the timing of the discrete-to-linear transition. Watch three things as we get closer: how far north the warm front lifts, whether storms stay discrete long enough during peak heating, and how quickly the line takes over. Those levers decide whether this is a localized strong-tornado event embedded in a larger wind threat, or something broader.

I will update both platforms as the Day 2 and Day 1 outlooks come into focus and the mesoscale details sharpen.

Moderate Risk in Place. SPC has an Enhanced Risk (level 3 of 5) for today covering eastern Kansas, much of western and central Missouri, and northeastern Oklahoma. Damaging wind is the headline threat, with large hail and a couple of tornadoes filling out the rest of the card. The evening hours along the cold front are the part of the day to circle.

The Setup

We’re working in the base of a broad, large-scale trough draped across the northern CONUS, with a strong belt of midlevel westerlies running through it. An embedded shortwave (a smaller ripple in that flow) of positive tilt swings across the northern Plains through the day. At the surface, a weak low drifts slowly east across western and central Kansas before a cold front overtakes it this evening. That front is the main focusing mechanism for the better-organized storms later on.

The thermodynamics cooperate. Steep midlevel lapse rates, meaning temperature falling off quickly with height, which lets updrafts accelerate, sit on top of a rich, moist boundary layer. That stacking builds a strongly unstable air mass by peak heating. Effective shear around 40 knots is enough to organize storms into clusters and semi-discrete supercells.

Timing and Evolution

Early in the period, a cluster of elevated storms tracks east from Nebraska into Iowa along the nose of a weakening nocturnal low-level jet. Steep lapse rates and 40 to 50 knots of effective shear favor large hail with that activity, though it stays mostly north of the main risk area.

Closer to the heart of the threat, a midlevel impulse and leftover convection push east from eastern Kansas into Missouri through the morning. Daytime heating of the moist air mass should build coverage and intensity along the resulting outflow into the afternoon. Moderate surface-based instability and 30 to 40 knots of effective shear support organized clusters and a few supercell structures, both capable of damaging wind and large hail.

Farther west, strong heating ahead of the surface low fires scattered storms from the central Plains into the lower Missouri Valley. These begin as semi-discrete supercells with large hail and locally damaging wind. As the cold front advances southeast into the evening, expect upscale growth into one or more organized clusters tracking east-southeast through a corridor of strong instability. That’s when the wind threat peaks, with some gusts potentially reaching 75 mph or higher.

Primary Threats

1. Damaging wind. The evening upscale-growth scenario along the front is the primary concern, with the potential for a swath of strong gusts as clusters consolidate and ride the instability gradient east-southeast.

2. Large hail. Best odds with the more discrete storms earlier in the cycle, before everything congeals into lines and clusters.

3. Tornadoes. Lower-end but not zero. Despite the lean toward upscale growth, embedded supercells stay possible, and with ample low-level shear and rich moisture in place, a brief tornado or two can’t be ruled out.

Confidence

Confidence is high that severe storms occur somewhere inside the Enhanced area. The wind and hail threats are well-supported by the instability and shear profiles. The open question is storm mode: how fast storms grow upscale into clusters versus how long they stay discrete. Some guidance leans toward earlier upscale growth, which tilts the day toward wind over tornadoes. If storms hold discrete longer than expected, the hail and tornado threats both tick up. Either way, the evening along the front is the time that matters.

Meteorologist Memo

This is a meat-and-potatoes Plains severe setup for mid-June: good instability, enough shear to organize, and a front to pull it together by evening. Nothing about it screams high-end, but Enhanced days earn their keep, especially after dark when storms are toughest to see coming. If you’re in the zone, keep warnings within reach tonight. I’ll update if the mode question tips one way or the other.

Moderate Risk Issued Today. SPC has upgraded part of the Midwest into the Great Lakes to a Moderate Risk, level 4 of 5. Damaging wind is the primary and most widespread threat, large hail comes with the stronger afternoon cells, and a corridor of strong tornado potential is on the table if storms stay discrete long enough. The risk area runs from Iowa and northeastern Missouri across northern and central Illinois, southern Wisconsin, northern Indiana, and central and southern Lower Michigan.

The setup. A potent mid-level trough is ejecting across the Upper Midwest into the Great Lakes, and it is dragging unusually strong mid-level winds along with it, on the order of 80 to 100 knots out of the southwest. That kind of flow in mid-June is the engine for today. At the surface, a low is deepening and lifting north out of the central Plains, with a trailing cold front to its south and a warm front (reinforced by leftover outflow from this morning’s storms) lifting north into the upper Midwest. The strengthening low-level jet keeps feeding moisture and warm air northward, which is what lets the atmosphere recover quickly behind the morning activity.

Timing and evolution. A severe MCS, meaning a large organized cluster of storms, is already ongoing this morning from southern Iowa into western Illinois. That is your first wind threat, with potential for significant gusts in the 70 to 75 mph range pushing east, possibly reaching Michigan by mid-afternoon. The afternoon is the more conditional part. As the warm front settles into northern Illinois and southern Wisconsin, new storms should fire along the front and near that boundary. Strongly sheared profiles favor supercells right out of the gate, capable of very large hail and tornadoes, a few of which could be strong to intense. The catch is mode and longevity: how long those cells stay discrete before they grow upscale into a bowing, wind-dominant line into the evening.

Where the uncertainty lives. The wind threat is high confidence. SPC carries a 45% wind probability with a significant (hatched) component, and that is well supported given both the morning MCS and a likely second round of bowing segments later. The tornado story is the wild card. It hinges on boundary placement and how cleanly the warm sector recovers behind the morning convection. If a sharp, well-positioned warm front sets up and supercells stay discrete through peak heating, a focused tornado corridor could come into better view in later outlook updates. The current 10% tornado and 15% hail numbers reflect that conditional ceiling, not a locked-in outcome.

What to watch. The single most important variable today is that warm front. Its exact latitude decides where the best low-level shear overlaps the strongest instability, and that overlap is where any strong tornado would come from. Keep an eye on where this morning’s storms leave their outflow, since that often anchors the afternoon boundary.

If you are in the footprint, treat the wind threat as the baseline and the tornado threat as the upside risk. Make sure warnings can reach you, and do not let the line’s arrival after dark catch you off guard.

For those new, welcome to Simply, Weather… on Substack.

Glad you’re here.

If you just subscribed, you’re joining a growing group of folks who want their weather straight, without the hype machine cranked to eleven every time a cold front swings through. That’s what I’m trying to build here, and I’m grateful you’re along for the ride.

Who’s behind this

I’m a degreed meteorologist with a soft spot for the wild stuff: hurricanes spinning up in the Gulf, supercells rolling across the Plains, and those big winter storms that have everyone arguing about snow totals four days out. Tropical, winter, and severe convective weather are where I spend most of my time, but I cover the country and the day-to-day too. If something significant is brewing somewhere in the Lower 48, I want you to hear about it here first, or at least hear it explained better here than anywhere else.

The goal of Simply, Weather has always been the same: real meteorology, presented honestly, written for humans. No fearmongering. No buried leads. No pretending models agree when they don’t.

A little honesty about cadence

I want to set expectations early, because trust matters more than volume.

Life at home is full right now. I’ve got a wife and an infant, and anyone who’s been through the newborn stretch knows the schedule belongs to the baby, not to me. So Simply, Weather isn’t going to be a post-every-morning operation, and I won’t pretend otherwise. What it will be is reliable when it counts.

When high-impact weather is on the table, a major severe outbreak, a landfalling hurricane, a significant winter storm, a pattern shift worth flagging, I’m going to be here with a discussion. That’s the promise. Quieter weeks may bring a long-range pattern piece or a deeper dive into something I find interesting. Busy weather weeks will bring more. I’d rather give you a smaller number of forecasts you can actually trust than flood your inbox with filler.

If a quiet stretch passes without much from me, that probably means the atmosphere is genuinely quiet, and you’re not missing anything.

What you can expect from the discussions

Each piece will walk you through the setup, the timing, the impacts, and where my confidence sits. I’ll show the reasoning, not just the conclusion. If the models are fighting, I’ll tell you. If a setup is unusually clean and I’m leaning hard one way, I’ll tell you that too. The reasoning is the value, and I’d rather you understand why a forecast is what it is than just take my word for it.

You’ll see some meteorological terminology in here. I’ll translate the heavier stuff so nobody gets left behind, but part of what I want this newsletter to do is help curious readers actually pick up the language over time. Stick around long enough and you’ll start spotting ridge axes and deformation zones in the wild.

For those who’ve been here a while

Some of you have been reading since the early days, back when Simply, Weather was a much smaller corner of the internet and the subscriber count fit on one screen. I see you, and I don’t take it for granted.

You’ve stuck with me through landfalls, blizzards, busted forecasts, and the quiet stretches in between. You’ve sent the kind notes when a call went well and the honest pushback when something needed a second look. That kind of feedback has shaped the way I write these discussions, and it’s a big part of why this newsletter sounds the way it does. Thank you. Genuinely.

A few of the things ahead are built with you in mind too.

What’s coming next

Two big things are in the works, and longtime readers will be the first to hear when each goes live.

The Book. I’m working on a book right now. It’s been simmering in the background for a while, and I’m finally putting real time against it. Without giving away too much, the goal is to write the kind of weather book I wish had existed when I was getting into the field: rigorous enough to respect the science, readable enough that a curious non-meteorologist could finish it and actually understand how the atmosphere behaves. It’s a slower process than I’d like, especially around the baby’s schedule, but it’s moving. I’ll share more as chapters take shape, and Substack subscribers will get the earliest looks at excerpts.

The Mobile App. Alongside the book, a Simply, Weather mobile app is in development. The idea is simple: the same honest, plainspoken forecasting you get here, in a format you can pull up on your phone during a watch box or a winter storm warning. I want it to feel less like a generic weather app and more like having a forecaster in your pocket who actually explains what’s going on. Still early, still a lot to build, but it’s coming. Newsletter subscribers will get first access when it’s ready to test.

Thanks for being here

That’s really the whole pitch. Honest forecasts, real reasoning, written by a person who happens to also be rocking a baby to sleep between model runs. A book on the way. An app on the way. And a community of readers, new and longtime, that I’m lucky to write for.

Whenever the next big system spins up, I’ll see you in your inbox.

-John
Founder | Simply, Weather

Synoptic Overview

The pattern amplifies meaningfully through the weekend. A deep mid-level trough digging into the western CONUS will swing southeast across the Great Basin and Four Corners through Sunday, then take on a negative tilt as it ejects across the central Plains on Monday. That progression is what turns a respectable Sunday setup into a potentially significant Monday.

At the surface, lee cyclogenesis spins up a low across eastern Colorado and western Kansas, with a warm front draped east-northeast through Nebraska and Iowa on Sunday. Strong southerly return flow taps the Gulf, advecting mid-60s dewpoints north into the central and southern Plains. By Monday, that low deepens further over western Kansas as the upper jet streak rounds the base of the trough, and a dryline sets up south of the low into western Oklahoma and the Texas Panhandle.

The Monday setup checks the boxes you want to see (or fear, depending on where you sit). Strong deep-layer shear, steep mid-level lapse rates riding under the elevated mixed layer, robust low-level moisture, and a strengthening nocturnal low-level jet curling the hodograph in the lowest kilometer. Translation for general readers: the atmosphere will have plenty of fuel, plenty of wind change with height, and the right ingredients to rotate.

Sunday, May 17

The Enhanced Risk stretches from central Nebraska northeast through southeast South Dakota, southwest Minnesota, and northwest Iowa. The play is twofold.

First, supercells. Initiation looks likely along and near the stationary warm front in eastern Nebraska by mid to late afternoon, with MLCAPE of 2,000 to 3,000 J/kg (a measure of how much instability storms can tap, with anything over 2,000 generally considered moderate to strong) and effective bulk shear well into supercell territory. Storms near the boundary should have access to backed surface winds, locally enhancing 0 to 1 km storm-relative helicity (the low-level rotational energy storms can ingest). That’s where the tornado threat lives, and the SPC explicitly mentions a few of those could be strong.

Second, upscale growth. As the low-level jet ramps to 40 to 50 knots through the evening and storms cluster, the mode shifts toward a damaging wind threat. Expect that transition to begin late evening, with the wind threat spreading downstream into southeast South Dakota, northwest Iowa, and southwest Minnesota overnight. Very large hail of 2 to 3 inches is also in play with any sustained discrete supercells before mergers compromise mode.

There’s one wild card. Morning elevated convection across northern Nebraska and Iowa could leave behind cloud debris and dampen destabilization in spots. South-central and southeastern Nebraska, where clearing looks best, become the most likely target for the tornado-favorable air mass.

Monday, May 18

This is the day. The SPC has now upgraded central Kansas into southeastern Nebraska to a Moderate Risk, level 4 of 5.

Moderate Risks on Day 2 are not common. The forecast team issues them when the ingredients are aligned cleanly enough, and with enough confidence, to flag a setup capable of significant, organized, potentially long-lived severe weather. The current SPC discussion calls out strong to intense tornadoes, very large hail, and damaging winds across the same corridor where the discrete supercell window will be open the longest.

Here’s what the environment looks like ahead of the dryline by late Monday afternoon:

• Moderate to strong instability with MLCAPE potentially 3,000+ J/kg

• Effective bulk shear of 50 to 60+ knots

• Steep low- and mid-level lapse rates, supportive of intense updrafts and very large hail

• A southerly 40 to 50 kt low-level jet shifting into central Kansas in the evening, enlarging low-level hodographs

• Mid-60s surface dewpoints, possibly higher in spots

If storms stay discrete on the dryline (and given the strong deep-layer shear, they should at least initially), supercells become near-certain. Very large hail of 2 to 4 inches is likely with the first storms. As the low-level jet ramps up through evening, the tornado threat climbs sharply. Long-track tornadoes are on the table, and given the EML overhead and the moisture quality, those storms can be classic Plains supercells, the kind that don’t apologize.

The pivot point Monday is upscale growth. As the cold front shoves southeast through the evening, storms will eventually merge and the line will take over, transitioning the threat to widespread damaging winds across eastern Kansas, Missouri, and southern Iowa overnight. Where the dryline storms remain discrete the longest, that’s where the tornado risk is highest. Forecast guidance has converged on central Kansas into southeast Nebraska for that window, which is precisely why the Moderate Risk sits where it does.

A secondary, lower-confidence threat exists farther south along the dryline into western Oklahoma and northern Texas. Stronger capping and weaker forcing favor a more conditional setup, but if the cap breaks, the same hazards apply on an isolated basis.

With the Moderate Risk already on the board at this lead time, a further upgrade to High Risk on Monday’s Day 1 outlook cannot be ruled out if mesoscale guidance continues to converge on a clean discrete window.

Tuesday, May 19

The front sweeps eastward Tuesday, with the severe corridor shifting into the Mid-Mississippi Valley, Ohio Valley, and Great Lakes. The current Day 4 outlook covers a broad swath from the northern part of the southern Plains northeast into the Great Lakes at 15 percent.

The big change is that the strongest upper-level flow lifts north of the best instability axis, which usually argues against a high-end tornado day east of the Mississippi. The likely flavor Tuesday is scattered damaging wind and hail with embedded supercells in the warm sector, particularly where the boundary moves through during peak heating. Specifics will refine considerably once the event becomes Day 2 and Day 3 territory tomorrow and Monday.

Confidence and What Could Change It

Sunday: High confidence in severe weather across the Enhanced Risk. Moderate confidence on the strong tornado threat. The biggest variable is storm mode and the influence of morning convection on destabilization. If clearing is more robust across eastern Nebraska, the tornado threat trends up. If lingering clouds and outflow muck things up, the wind threat dominates.

Monday: High confidence in significant severe weather, with strong to intense tornadoes possible across central Kansas into southeast Nebraska. The Moderate Risk reflects that confidence. The biggest remaining variable is the exact timing of dryline initiation and whether the cap breaks cleanly in the discrete window. If it breaks early and storms remain isolated for two to four hours before linear growth, this becomes a potentially significant tornado afternoon. If the cap holds late and storms initiate close to the front, mode degrades faster and the threat consolidates around wind and hail. Worth flagging: a further upgrade to High Risk on Monday’s Day 1 is on the table if the discrete window tightens up further in mesoscale guidance overnight.

Tuesday: Lower confidence on specifics. The pattern degrades as the trough lifts northeast and instability and shear axes separate. Still a real severe threat, just not the same caliber.

Forecaster’s Note

Sunday is a serious day where it matters. Monday is the kind of setup that, if you live anywhere from Russell to Lincoln, you should treat with the respect it deserves. The mid-May Plains can do real damage when the trough goes negative and the dryline lights up, and right now the pattern is lining up like it wants to do exactly that. I’d rather sound the right alarm three days out and have it underperform than wait politely for confirmation.

Have a way to get warnings overnight Sunday into Monday, especially the people of central and southeastern Kansas and southeastern Nebraska. Know your closest interior, lowest-floor shelter. Have a plan that doesn’t require thinking.

Simply, Weather. is a reader-supported publication. To receive new posts and support my work, consider becoming a free or paid subscriber.

Subscribe now

What’s happening?
The main “engine” behind these storms is a series of disturbances moving out of the western U.S. These are hitting a stalled front sitting right over the middle of the country, which is acting like a tracks for these storms to follow.

Pledge Your Support for the Simply, Weather! Thank you for your support!

Subscribe now

• Today (Wednesday): Our biggest concern is across the Southern and Central Plains (Texas, Oklahoma, and Kansas). The atmosphere is very unstable today, which means any storms that form could quickly become “supercells.” These are the types of storms that can produce very large hail (think golf balls or bigger) and a few tornadoes.

  

• Thursday: As the system moves toward the Great Lakes, the risk shifts into the Mid-Mississippi Valley, including states like Illinois, Indiana, and Michigan. While the tornado risk is a bit lower here, we are still watching for damaging wind gusts and isolated tornadoes as a line of storms pushes through.

  

• Friday & Saturday: We aren’t out of the woods for the weekend. Another strong system will move in from the Rockies, pulling up even more moisture from the Gulf. This will likely trigger a final, powerful line of storms stretching from Texas all the way to the Ohio Valley on Saturday before much colder air finally moves in on Sunday to quiet things down.

  

The Bottom Line:
Between now and Saturday night, we are facing risks for tornadoes, damaging winds, and large hail. Because some of these storms will “train” (meaning one storm follows right behind another over the same area), there is also a high risk for flash flooding in many spots.

Please stay weather-aware! This is a fast-moving and volatile setup. Make sure you have your phone alerts turned on, keep a weather radio handy, and know exactly where your “safe place” is in your home. We’ll keep you updated as things evolve!

A meaningful and potentially dangerous severe weather outbreak is expected to unfold across a large portion of the eastern United States on Monday, March 16. This is not a marginal or uncertain setup. The ingredients are in place, confidence is high, and the threat is serious enough to warrant attention and preparation.

THE ATMOSPHERIC SETUP

Every significant severe weather outbreak starts with a favorable large-scale pattern, and Monday’s event has one. A large, deepening upper-level trough, essentially a pronounced dip in the jet stream, will pivot northeastward out of the Ohio and Tennessee Valleys, crossing the Appalachians and digging into the Mid-Atlantic through the day. At the surface, a low-pressure system will be deepening rapidly into southern Canada, and a sharp pre-frontal trough will extend southward across New York, Pennsylvania, and into the Carolinas and Georgia by late afternoon.

That pre-frontal trough matters. It is a zone of focused convergence and pressure falls that often serves as the trigger for the most intense convective development. When it arrives during the peak heating hours of the afternoon, it will do so into an atmosphere that has been primed and loaded.

Ahead of the cold front, gusty southerly winds will advect warm, moist air northward throughout the day. Surface dewpoints in the 60s F are expected across the entire threat corridor, reaching as far north as southern Pennsylvania. For mid-March, that is a remarkably rich moisture environment and one that significantly increases the fuel available for severe storms.

Pledge Your Support for the Simply, Weather Publication!
Thank you for your support!

Subscribe now

WIND THREAT

The wind threat on Monday is, in many ways, the broadest and most widespread hazard of the day. At 850 millibars, roughly 5,000 feet above the surface, southerly winds are forecast to increase from 50 to 75 knots through the afternoon. That translates to an extreme vertical wind shear profile across a large area, meaning the atmosphere will be extraordinarily supportive of organized, long-lived convective systems.

A robust squall line is expected to develop along and behind the cold front, stretching from the Carolinas northward toward southern New York. With a deeply moist air mass in place and strong large-scale forcing overhead, this line will be capable of producing particularly damaging wind gusts, potentially well in excess of 70 to 80 mph in the most intense cores. Wind probability contours from the Storm Prediction Center reach 60% for severe wind gusts of 58 mph or greater within the Moderate Risk corridor. Significant severe wind, defined as gusts of 75 mph or greater, is also possible within the highest-risk area.

These are winds capable of causing significant structural damage, widespread power outages, and downed trees across densely populated areas. The Mid-Atlantic corridor, which includes major metro areas from Charlotte to Washington D.C. and Baltimore, is squarely in the crosshairs.

TORNADO THREAT

While the wind threat is the broadest hazard, the tornado threat may be the most dangerous in a concentrated sense. Ahead of the main cold front, discrete supercell thunderstorms are expected to develop across the Carolinas and track northward into southern Virginia during the afternoon hours. This is the portion of the setup that carries the highest end potential.

Forecast storm-relative helicity values of 300 to 400 meters squared per second squared, and potentially higher with later model updates, indicate a strongly favorable environment for sustained low-level rotation. Hodograph analysis shows enlarged, curved profiles in the low levels, which is exactly the kinematic signature associated with supercells capable of producing significant, long-tracked tornadoes. Fast storm motions, estimated at over 50 knots, mean that any tornado which does touch down could cover ground very quickly, giving communities very little time to respond.

Strong tornadoes, EF2 and above, are explicitly possible within this corridor. The Storm Prediction Center’s tornado probability reaches 15% within the Moderate Risk area, with a significant tornado hatch likely to be introduced with updated outlooks through the day Monday. That combination, 15% tornado probability plus a significant tornado hatch, is a meteorological signal that demands serious attention.

Early in the day, across Georgia and the Florida Panhandle, the atmosphere will already be favorable for supercell development. Forecast soundings show substantial instability with midlevel lapse rates approaching 7 degrees Celsius per kilometer, a steep enough profile to support large hail in addition to tornadoes in the morning hours.

For the QLCS, the quasi-linear convective system, or squall line portion of the event across the Carolinas northward, embedded QLCS tornadoes are also expected. These are tornadoes that form within the line itself, often with very little warning time, and they add another layer of complexity to an already dangerous setup.

RISK AREAS AND TIMING

The Storm Prediction Center has issued a Moderate Risk, Level 4 of 5, from northern South Carolina through North Carolina and into Virginia and Maryland. This is a high-confidence categorical placement, meaning forecasters are confident enough in the threat to elevate beyond the Enhanced Risk designation. Significant severe storm potential extends outward across eastern Georgia, the Florida Panhandle, and southern Pennsylvania.

Timing matters enormously for preparation purposes. Severe storm activity will likely be ongoing across Georgia and the Florida Panhandle during the morning hours Monday. The setup then intensifies dramatically through the afternoon as heating peaks and the pre-frontal trough deepens. The most dangerous window for the Carolinas, Virginia, Maryland, and southern Pennsylvania is roughly midday through early evening. Some activity, particularly the squall line portion, may linger into the overnight hours.

A CALL TO ACTION

If you live anywhere from the Florida Panhandle northward through the Mid-Atlantic, Monday is a day to be actively weather aware, not passively aware. There is a meaningful difference between those two things.

Actively weather aware means you have already identified your safest shelter location, ideally an interior room on the lowest floor of a sturdy building, well away from windows. It means you have a way to receive warnings in real time, whether through a weather alert app, a NOAA weather radio, or both. It means you have a plan for what to do if conditions deteriorate rapidly, and that plan does not involve waiting to see what happens.

Do not let a quiet morning lull you into complacency. Some of the most dangerous severe weather outbreaks unfold precisely because people assumed things would stay quiet. With events like this one, the window from clear skies to dangerous conditions can be short.

This setup is the real thing. Please take it seriously.

Stay weather aware. Stay safe.

The spring 2026 severe weather season has not waited for the calendar. An EF-2 tornado struck Bloomington, Indiana, on February 19, carving a 3.7-mile path with 120 mph winds and prompting a rare PDS tornado warning. At least six tornadoes were confirmed across southern Illinois and Indiana that evening. Severe storms swept from Texas to the Gulf States on February 14-16. Five tornadoes hit Oklahoma on January 8. Through mid-February, the U.S. had already logged roughly 23 confirmed tornadoes, multiple rated EF-2, before the climatological ramp-up of severe weather season has even begun.

These events are not random. They are early expressions of a large-scale atmospheric configuration that, by multiple measures, points toward an active spring for tornadoes and severe thunderstorms across the central and southern United States. The drivers are converging in a way that warrants detailed examination.

The ENSO Transition: Rapid Collapse, Potent Residual Signal

As of the most recent IRI quick look (mid-February 2026), the weekly Nino 3.4 index has risen to -0.2 degrees Celsius, a dramatic warming from the -1.10 degrees Celsius observed in December and -0.54 degrees Celsius in January. The La Nina is collapsing with remarkable speed. The IRI multi-model plume now places a 96% probability of ENSO-neutral conditions for the February-April period, with La Nina’s probability down to just 4%.

However, the atmospheric story is more nuanced than the Nino 3.4 trajectory suggests. CPC’s Relative Oceanic Nino Index (RONI), which became the official ENSO monitoring metric on February 2, 2026, measures SST anomalies in the Nino 3.4 region relative to the broader tropical mean. By this measure, La Nina’s influence has been substantially more robust: the RONI for the five most recent overlapping three-month periods (July-September through November-January) was -0.63, -0.77, -0.87, -0.93, and -0.97 degrees Celsius, respectively. That is a progressively intensifying cold signal through the RONI lens, even as the traditional ONI was showing weakening. The Copernicus C3S models also recorded a Nino 3.4 index of -1.05 degrees Celsius for the October-December 2025 three-month average.

This distinction between the two metrics is consequential for severe weather. The atmosphere responds to the actual SST patterns and their influence on tropical convection, the Walker Circulation, and the resulting teleconnections to mid-latitude jet stream behavior, not to a single index threshold. The La Nina signal embedded in atmospheric circulation this winter has been more impactful than a traditional “weak La Nina” characterization would suggest.

Research from Allen, Tippett, Lepore, and others has demonstrated that La Nina conditions enhance tornado-favorable environments across the south-central and southeastern U.S. through several mechanisms: a more amplified jet stream with increased troughing over the central U.S., more frequent cyclogenesis east of the Rockies, enhanced southerly moisture transport from the Gulf, and increased frontal frequency. These are the organizing agents for severe weather. Critically, these atmospheric patterns exhibit inertia. The jet stream configuration established during winter does not instantly recalibrate when the Nino 3.4 index crosses -0.5 degrees Celsius. The residual signal persists through the March-April severe weather window, which is precisely when climatological tornado frequency ramps up.

The analog years for La Nina-to-neutral transitions (2021, 2018, 2012, 2011, 2006, 2001, 1996) show high variance, but the extremes are notable. The 2011 transition produced one of the most catastrophic tornado seasons in U.S. history, including the April 25-28 Super Outbreak. That year also featured a rapidly collapsing La Nina with a strong residual atmospheric signal.

Looking further ahead, multiple modeling systems, including ECMWF, NMME, and the IRI plume, are showing El Nino probabilities rising through summer 2026. The Copernicus C3S models predict ENSO-neutral from March onward, with some models suggesting El Nino development as early as late summer. Rapid ENSO phase transitions can produce volatile mid-latitude patterns during spring as the tropical forcing evolves.

Stratospheric Forcing: The SSW Event and Persistent Cold Air Accessibility

The 2025-2026 winter featured a significant Sudden Stratospheric Warming event that caused a full polar vortex split in mid-February. The January-February 2026 North American cold wave, directly linked to the SSW-driven polar vortex displacement, caused an estimated $4 billion in damages and at least 22 direct fatalities. Record lows were set from Canada to Central America.

The February 19 tornado event in the Ohio Valley was a direct downstream product of this atmospheric configuration. The post-SSW pattern has maintained cold air accessibility at higher latitudes, so that when a transient shortwave trough ejects into the warm sector and surface-based instability develops, the thermal gradient across the frontal zone is anomalously sharp. That is exactly what happened last Wednesday: 70-degree temperatures in the warm sector across southern Indiana, cold air just to the north, and the resulting wind shear profile that supported supercells capable of producing EF-2 tornadoes.

The SPC’s Day 4-8 outlook as of this morning (February 24) notes that severe weather potential will remain low through the current forecast period as the atmosphere undergoes a pattern change. An expansive upper-level ridge is taking shape across much of the U.S., while a closed low develops across the Southwest. A frontal boundary will stall along the northern Gulf Coast, confining appreciable low-level moisture to the Gulf through the weekend. However, by early next week (Days 7-8), the SPC identifies a regime transition: a split-flow pattern (ridge over trough) with an arctic front pushing into the northern tier, followed by Pacific shortwave energy potentially overrunning the colder air mass across the Mississippi Valley into the Mid-Atlantic by early March.

This is the kind of synoptic cycling, active warm sectors followed by reinforcing cold air, that sustains multi-week severe weather episodes through March and April. The cold air supply is not going away. It is being periodically refreshed, and each time the warm sector rebuilds and a new trough arrives, the severe weather potential recharges.

Gulf SSTs and Low-Level Moisture Transport

Gulf sea surface temperatures are a critical modulator of severe weather, and the Gulf has been running warmer than average through this winter. Research from Molina et al. (2016) established the physical chain: warmer Gulf waters enhance evaporation, increase boundary-layer dewpoints, strengthen the low-level jet, and increase CAPE when that moisture is advected northward into the warm sector of mid-latitude cyclones.

The Gulf SST-ENSO relationship is well-documented. Gulf temperatures are negatively correlated with tropical Pacific SST, meaning La Nina periods favor warmer-than-average Gulf waters. The long-term warming trend in the Gulf (approximately 0.19 degrees Celsius per decade since 1970, roughly double the global ocean average, per research published in the Journal of Climate in 2023) acts as a background amplifier. Each successive spring season starts with a slightly warmer Gulf baseline, providing incrementally more moisture and energy for severe convection.

The combination of a warm Gulf, an active jet stream, and accessible cold air is the trifecta that produces the most consequential severe weather episodes.

Jet Stream Configuration and the Severe Weather Corridor

The spring 2026 jet stream pattern is being shaped by the intersection of the collapsing La Nina, the post-SSW polar vortex disruption, and Pacific blocking. The ECMWF and UKMO seasonal models both show a persistent low-pressure zone over Canada maintaining cold air accessibility, with above-normal precipitation favored from the northern U.S. through the Midwest.

The CPC seasonal outlook favors above-normal precipitation from the Great Lakes to the Ohio Valley and Appalachians, above-normal temperatures for the Northeast and Mid-Atlantic from March through May, and a continued severe weather corridor from the Mississippi Valley through the Gulf States.

AccuWeather’s seasonal team notes that storm systems this spring may track more slowly, increasing rainfall totals, flooding risk, and the duration of individual severe weather events. The greatest risk for severe weather is expected to focus from the Mississippi Valley into the Gulf States during March and April, expanding northward into the central Plains and Midwest during late April and May.

A Note on the SPC’s New Conditional Intensity Groups

One week from today, on March 3, the SPC will implement Conditional Intensity Groups (CIGs) in their Day 1, 2, and 3 Convective Outlooks. This is the most significant change to SPC forecast products in years.

For tornadoes, the system adds three intensity levels: CIG 1 indicates maximum forecast tornado intensity around EF-2. CIG 2 indicates EF-3 potential. CIG 3 indicates EF-4 or EF-5 potential.

For wind, three levels correspond to gusts up to 75 mph (CIG 1), longer-track events like bow echoes or derechos (CIG 2), and high-end derechos (CIG 3). Hail receives two levels: supercells capable of 2-inch hail (CIG 1) and very large hail of 3.5 inches or more (CIG 2).

These replace the old “significant” hatched area, which only conveyed a 10% probability of significant severe weather without differentiating between an EF-2 and an EF-5. The new system will give us substantially better tools to communicate the severity of tornado and severe weather threats during the busiest part of the spring season. I will provide a detailed walkthrough of the new products when they launch.

Synthesis

The spring 2026 severe weather season has multiple atmospheric drivers aligning in a pattern that historically has produced consequential seasons:

The March-April window carries the greatest risk, with the primary corridor extending from the Mississippi Valley through the Gulf States, Tennessee Valley, and Ohio Valley. The February 19 EF-2 tornado in Bloomington demonstrated that this corridor is already capable of producing significant severe weather when the ingredients align, and the ingredients will align more frequently and more intensely as the season progresses.

Late April through May should see the threat expand northward into the central Plains and Midwest as the warm sector broadens and the jet stream migrates.

The early-season evidence is notable. Through mid-February, the U.S. had recorded approximately 23 confirmed tornadoes, including multiple events rated EF-2. January 8 produced five tornadoes in Oklahoma. February 14-16 brought severe weather from Texas to the Gulf States. February 19 produced at least six tornadoes including a PDS-warned EF-2 in Bloomington, the highest-impact severe weather event of 2026 to date. This activity is occurring before climatological severe weather season has even begun in earnest.

I want to be transparent about uncertainty. Seasonal severe weather prediction is inherently limited. ENSO explains only a portion of the variance in tornado activity, and individual events depend on mesoscale processes that are unknowable at seasonal timescales. I am not predicting a specific number of tornadoes this spring.

What I am saying is this: the large-scale atmospheric ingredients are loaded. The synoptic pattern resembles historical configurations that have produced active seasons. And the atmosphere is already validating that assessment with real-world events.

Preparedness

Review your severe weather plans now. Know where your shelter is. Have multiple ways to receive warnings, with NOAA Weather Radio as the gold standard. Understand the difference between watches and warnings. Practice your plan.

The SPC’s new Conditional Intensity Groups launch March 3. I will walk you through those changes in a dedicated post.

I will be here throughout the season, providing updates as each significant event develops and as the pattern evolves. The atmosphere has already spoken. It is our responsibility to listen and help people act on that information when it matters most.

This weekend into Monday, a classic nor’easter will rapidly intensify along the East Coast, bringing blizzard conditions, coastal flooding, and dangerous wind to a densely populated stretch of the country. Blizzard warnings are in effect from coastal New Jersey and New York City all the way through coastal Connecticut and southeastern Massachusetts, including Cape Cod and the Islands. For New York City, it marks the first blizzard warning in nearly a decade.

How a Nor’easter Works

The term “nor’easter” gets used frequently in winter weather coverage, but it is worth understanding what actually defines one. A nor’easter is a low pressure system that tracks northeastward along the East Coast, with winds wrapping around the storm blowing persistently out of the northeast. This northeast wind fetch is important because it draws cold air down from Canada on the western side of the storm while simultaneously pulling enormous amounts of moisture off the Atlantic on the eastern side. When those two ingredients combine, you get heavy precipitation in a very energetic environment.

The storm’s origin is equally important. This system is developing in the Gulf Coast region Saturday before tracking toward the Mid-Atlantic coastline and ultimately intensifying offshore. That southerly origin means the storm is loaded with moisture, which translates to heavy, wet snow rather than the light, fluffy variety. While wet snow is easier to shovel in small amounts, it becomes a serious concern in large accumulations because of its weight on roofs, trees, and power lines. That is why power outages are considered a significant threat with this event.

Bombogenesis: The Atmosphere in Fast Forward

The most important meteorological concept driving the intensity of this storm is a process called bombogenesis, or more casually, a “bomb cyclone.” This occurs when a low pressure system’s central pressure drops by at least 24 millibars in 24 hours, a threshold that meteorologists use to define rapid intensification. Pressure in the atmosphere is a measure of how much air is piled above a given point. When pressure drops rapidly, it means air is evacuating the center of the storm quickly, causing winds to rush in from surrounding areas with increasing force. The faster the pressure falls, the more explosive the intensification and the stronger the resulting storm.

This storm is expected to undergo bombogenesis as it moves into the waters off the Northeast coast Sunday night, with the peak of the storm arriving during the early morning hours Monday. Bombogenesis is common over the western Atlantic because of the sharp temperature contrast between the cold continental air mass and the warm Gulf Stream waters. That boundary acts like fuel for rapidly deepening coastal storms and is one reason nor’easters can intensify so dramatically in a short window of time.

What the Forecast Looks Like

The storm’s track is now coming into good focus, with the center expected to pass near or just southeast of the classic “benchmark” location at 40 degrees north latitude and 70 degrees west longitude. This benchmark position, just southeast of Nantucket, is historically associated with high-impact snow events for the I-95 corridor. When a nor’easter tracks near this location, it positions the heaviest snow bands right over the most populated areas of the Northeast.

Snow is expected to begin arriving Sunday afternoon and evening, initially as light snow or a rain-snow mix in some areas due to temperatures hovering just above freezing at the surface. As the storm intensifies and cold air wraps into the circulation overnight, temperatures will drop sharply and the heaviest snow will arrive. Snowfall rates during the peak of the storm could exceed one inch per hour for several hours across portions of New York, New Jersey, and southeastern Massachusetts.

Current snowfall projections are pointing toward 12 to 18 inches for New York City, Long Island, and coastal New Jersey. Boston and the eastern Massachusetts suburbs are looking at 10 to 16 inches, with Cape Cod and the Islands potentially seeing even higher totals depending on where the heaviest banding sets up. Philadelphia and surrounding suburbs are expected to see 8 to 12 inches.

The Blizzard Criteria and Why It Matters

It is worth clarifying that blizzard conditions are not simply about snow totals. The National Weather Service defines a blizzard as sustained winds or frequent gusts of 35 mph or greater, combined with falling or blowing snow reducing visibility to under a quarter mile, persisting for at least three consecutive hours. Under those conditions, travel does not just become difficult. It becomes life-threatening.

Wind gusts along the coast are expected to reach 50 to 70+ mph during the peak of the storm, particularly across southeastern Massachusetts, Cape Cod, and the Islands. These winds, combined with heavy snowfall rates and blowing snow, will create near-zero visibility conditions across warned areas Sunday night into Monday morning. Coastal flooding is also expected during several high tide cycles, with moderate to major flooding anticipated along the New York, New Jersey, Massachusetts, Connecticut, and Delaware coastlines due to the strong onshore wind push.

The Bottom Line

This storm is going to be significant. If you are in a blizzard-warned area, treat Sunday evening through Monday morning as a period to be completely off the roads. The combination of rapidly accumulating heavy wet snow, near-zero visibility, gusty winds capable of downing trees and power lines, and coastal flooding makes this a genuinely dangerous weather event for tens of millions of people.

Stay with updated forecasts through the weekend as timing and snowfall details continue to come into sharper focus, and make sure your preparations are complete before conditions deteriorate Sunday evening.

The Synoptic Setup

A broad upper-level trough that has been carving through the western U.S. this week will begin ejecting eastward into the Plains and Mississippi Valley by Thursday. As this trough amplifies, it will help deepen a surface cyclone tracking northeast of the lower Missouri Valley during the afternoon hours.

Ahead of this system, southerly flow at 850 mb is forecast to strengthen to 30–50 knots, transporting warmer and increasingly moist air northward through the warm sector. This low-level jet is a critical piece of the puzzle, it serves as both a moisture transport mechanism and a significant contributor to low-level wind shear. As the low-level jet intensifies Thursday afternoon, clockwise-curved hodographs will expand across the threat area, favoring storm rotation in any convection that can root itself in the boundary layer.

A warm front draped across the region and an approaching cold front will serve as the primary forcing mechanisms for storm initiation. Thunderstorms are expected to develop along and ahead of these boundaries during the afternoon, with the most favorable window running from roughly midday through the early evening hours.

The Thermodynamic Question

This is where the forecast gets nuanced, and where the biggest uncertainty lies.

Model guidance has been somewhat split on how much instability will be available. The latest NAM forecast soundings depict boundary-layer-based CAPE supportive of organized, low-topped convection. Meanwhile, a broader consensus of other models paints a more modest instability picture, suggesting that much of the moistening may occur beneath relatively warm mid- and upper-level temperatures, a byproduct of subsidence south of the upper-level jet axis. This would effectively cap the atmosphere and limit surface-based CAPE values.

The key variable to watch is moisture return. Current guidance suggests surface dew points could climb into the mid-50s to near 60°F across a corridor stretching northeast and east of the confluence of the Mississippi and Ohio Rivers. If dew points push toward the upper end of that range, instability will be more robust and the severe threat escalates. If moisture remains more marginal, the threat stays lower-end but doesn’t disappear, strong shear environments can still produce tornadoes even with modest CAPE, particularly in the form of low-topped supercells.

Wind Shear: The Overachiever in This Setup

While instability may be somewhat limited, the kinematic environment is the standout player Thursday. Deep-layer shear will be strong thanks to the amplifying upper trough and attendant jet stream energy. More importantly, the combination of a strengthening 850 mb southerly jet and veering wind profiles with height will produce impressive low-level shear values and enlarged hodographs, the kind of setup that supports supercellular storm mode and tornado potential even with relatively modest thermodynamic support.

The Storm Prediction Center has noted that any convection capable of becoming boundary-layer-based could acquire supercellular characteristics in this high-shear environment. There’s also the possibility that a small organizing convective cluster could develop, which would bring a greater threat for damaging straight-line winds.

Where and When

The primary threat zone extends from the middle Mississippi Valley into the lower Ohio Valley, with the highest confidence currently centered across parts of southern Illinois, Indiana, and western Kentucky, including the Wabash Valley and Evansville tri-state region. The SPC has placed a 15% severe probability across this area for Thursday, a Slight Risk (Level 2 of 5) at this range.

Timing favors Thursday afternoon into the early evening, roughly 1 PM–8 PM local time, with multiple rounds of convection possible as different forcing mechanisms interact with the warm sector.

Primary Hazards

• Damaging wind gusts: The dominant threat, especially if storms organize into a cluster or line segment. Strong deep-layer shear supports sustained severe gusts.

• Tornadoes: A few tornadoes appear possible, particularly with any discrete supercells that can tap into the enhanced low-level shear and curved hodographs. These would most likely be in the EF0–EF1 range, though a stronger tornado can’t be ruled out given the shear environment.

• Small to marginally severe hail: A secondary threat, mainly with any initial discrete cells before storms potentially congeal.

Limiting Factors Worth Monitoring

• Cloud cover: Persistent clouds ahead of the system could suppress daytime heating, limiting how much CAPE can develop.

• Capping: Warm air aloft from subsidence south of the jet could keep a lid on more vigorous convective development.

• Marginal moisture: If dew points remain in the low-to-mid 50s rather than surging into the upper 50s–60°F range, the thermodynamic environment stays on the weaker side.

Bottom Line

This is a shear-dominant severe weather setup where the kinematic environment is doing the heavy lifting. The question isn’t whether we’ll have wind shear, that’s a given, it’s whether enough instability and moisture will be in place for storms to take full advantage of it. Even modest CAPE in a high-shear environment can produce dangerous storms, so this threat should be taken seriously.

The forecast will continue to sharpen over the next 36–48 hours as higher-resolution models come into range. If you live anywhere from the middle Mississippi Valley through the lower Ohio Valley, now is the time to review your severe weather plan, ensure your weather alerts are working, and identify your safe shelter location.

I’ll continue to monitor this evolving setup and provide updates as the picture becomes clearer.

Stay weather aware…

Let me be clear from the outset: winter is not over. While we are indeed moving through a period of relatively milder conditions compared to some of the colder stretches we experienced earlier this season, there remain credible cold air intrusions and snow threats that have the potential to materialize into early March.

The CPC Temperature Outlook: What It Actually Means

This is perhaps the single most important point I want to make in this discussion, because it’s the source of the most widespread misunderstanding.

When the Climate Prediction Center issues its 6-to-10-day or 8-to-14-day temperature outlooks, and you see shades of orange and red covering the central and eastern United States, that does not mean temperatures are heading for the 60s and 70s in cold-prone regions. What it means is that the probability of temperatures being above the climatological normal for that particular time period is elevated.

This is a critical distinction. Climatological normals in mid-to-late February across much of the central and eastern U.S. are still firmly in winter territory. In many locations, normal highs are in the 30s and 40s. An “above normal” signal might translate to temperatures running 5 to 10 degrees above those values — perhaps the mid-40s to low 50s in spots that would typically be in the upper 30s. That’s a noticeably milder day, certainly, but it’s not spring. It’s still a period where precipitation can fall as snow, where overnight lows can dip below freezing, and where winter weather events remain very much in play.

The CPC outlooks are probabilistic products. They communicate the likelihood that temperatures will fall into the upper, middle, or lower third of the historical distribution for a given period and location. A warm shading means the odds are tilted toward the above-normal category, it says nothing about the magnitude of the departure, and it absolutely does not represent a forecast for specific temperature values.

The Road Ahead: Cold and Snow Threats Persist

With that context established, let’s talk about the pattern evolution through early March.

The most pronounced cold of this winter season, the deep Arctic intrusions and the most anomalously cold stretches, are very likely in the rear-view mirror at this point. The large-scale pattern evolution, including the state of key teleconnection indices and the general trend in the polar and subtropical jet stream configuration, supports the idea that we are unlikely to see the kind of sustained, deeply entrenched cold that characterized earlier portions of the season.

However, “the worst is behind us” is not the same as “it’s over.” The atmosphere doesn’t simply flip a switch from winter to spring. What we typically see during this late February into early March window is a progressive weakening of the polar jet and a gradual northward retreat of the primary cold air source regions, but this process is uneven. It occurs in fits and starts. Periodic shortwaves and troughing patterns can still tap into modified Arctic air masses and deliver meaningful cold air intrusions to the central and eastern U.S., even as the broader trend leans warmer.

Snow threats remain particularly relevant during this period. In fact, some of the most impactful snow events of the winter season can occur in late February and March, when there is still sufficient cold air available to support snow, but increasing atmospheric moisture associated with a strengthening subtropical jet and more vigorous storm systems provides the dynamic forcing for significant precipitation events. The juxtaposition of lingering winter cold and increasing spring-like energy is a recipe for high-impact weather.

Why Late-Winter Forecasting Is So Challenging

This is a topic that doesn’t get discussed enough, and it’s worth understanding because it directly affects the reliability of every forecast you see during this time of year.

Winter weather forecasting is inherently challenging, but the difficulty ramps up considerably as we move from February into March. The primary reason is the sun angle.

By late February, the solar elevation angle is climbing noticeably higher with each passing day. This has a cascading effect on the entire atmospheric energy budget. Increasing insolation means more surface heating during the day, which erodes shallow cold air masses more quickly, modifies snow cover, and introduces stronger diurnal temperature swings. A forecast for a snow event that might have been relatively straightforward in January becomes dramatically more sensitive to timing in late February or March. A storm arriving overnight, when the sun isn’t a factor, may produce significant accumulation, while the same system arriving during the afternoon hours could see surface temperatures just warm enough to mix in rain or dramatically reduce snow ratios.

The increasing sun angle also accelerates the destabilization of the lower atmosphere, which influences precipitation type, convective potential, and the overall behavior of frontal boundaries. The atmosphere is in a genuine state of transition, the radiative forcing is changing on a daily basis, and that makes the difference between a major winter storm and a non-event increasingly razor-thin.

This is compounded by the fact that model guidance during transitional seasons tends to show higher spread and lower consistency in ensemble forecasts, particularly beyond day five or six. The competing signals from lingering winter pattern features and emerging spring dynamics create a noisy forecast environment.

The Bottom Line

The coldest chapters of this winter are very likely behind us. But winter is not finished. Cold air intrusions and snow events remain viable threats through early March, and the pattern supports periodic reminders that the season still has teeth.

When you see warm colors on CPC outlook maps, remember what they represent: a tilt in probabilities, not a forecast for spring-like warmth. And as we navigate this challenging late-winter window, understand that the forecasts you’re seeing carry inherently more uncertainty than they did a month ago, not because the meteorology is getting worse, but because the atmosphere itself is in one of its most complex transitional phases of the entire year.

Stay weather-aware, stay patient with the forecast process, and we’ll continue to break it all down as the pattern evolves.

On the thermodynamic side, the cold is the higher confidence piece. Surface high pressure settling in, reinforced by additional surges, maintains an anomalously cold airmass. Where snow and ice cover exist upstream, radiational efficiency improves and cold air tends to “lock in” more effectively at night, which matters for the Southeast hard freeze risk and for p type along the coastal plain.

The storm side hinges on track, phasing, and mesoscale thermal boundaries. The favored evolution is northern Gulf frontal wave genesis, followed by downstream amplification into a significant coastal storm that deepens rapidly off the Southeast Saturday and then lifts toward the Mid Atlantic and New England Sunday. This evolution supports a corridor of heavy snow potential from the eastern Carolinas through parts of the Mid Atlantic into coastal southern New England, but the precise onshore footprint remains sensitive to subtle track differences. That is why confidence can rise on the storm existing, while confidence remains lower on exactly which metros land in the deformation band versus the mixing zone or the dry slot.

Practically, the next 24 to 48 hours of guidance should answer two questions. Does the track trend closer to the coast or hold farther offshore. Does the upper low remain strong and well phased as the coastal low intensifies. Those two items will largely determine the inland extent of impactful precipitation, the rain vs sleet vs snow gradient near the fall line, and how broad the wind and coastal impacts become.

Global Model output… the ECMWF at top, the GFS at bottom

High-Resolution Model output… the NAM at top, the RRFS-A at bottom

The reason for the northward correction comes down to storm strength. Earlier forecasts underestimated how quickly this system would intensify as it moves out of the Southwest and interacts with energy to the north. As newer data has been ingested, models are now showing a faster-deepening storm. When a storm strengthens more rapidly, it gains the ability to pull the temperature boundary northward. That boundary is the dividing line between cold air and warmer air, and where it sets up determines where heavy snow and dangerous ice occur. A stronger storm pulls harder, and that is why snow and ice threats have shifted north.

The atmospheric setup is unusually favorable for a significant winter event. Cold air is already in place at the surface across a large portion of the region. This cold air is deep and well-established, meaning it will not easily retreat once precipitation begins. At the same time, a strong storm system is drawing in moisture from the south and west and lifting it over that cold air. A helpful way to visualize this is warm, moist air gliding over a cold surface, similar to warm breath fogging a cold windshield. That rising motion is what produces widespread precipitation.

What type of precipitation falls depends on temperature changes with height. In areas where the entire atmosphere stays cold, snow will fall, and it could fall heavily where lift is strongest. In areas where warmer air pushes in aloft but cold air remains trapped near the surface, freezing rain and sleet become the dominant threat. This creates a dangerous overlap of hazards, with heavy snow on the cold side of the storm and potentially damaging ice just to the south and east of the snow band.

As the storm continues to intensify, winds increase and lift strengthens further. This often leads to the development of a very intense band of snow on the backside of the storm, where snowfall rates can become extreme for several hours. At the same time, the strengthening circulation enhances the icing threat in nearby regions, increasing the risk of power outages and tree damage. This combination of deep cold air, abundant moisture, strong lift, and a slowing storm track is what elevates this system into a rare, high-impact category.

The real-world impacts could be significant and long-lasting. Heavy snow may make travel extremely difficult or impossible in parts of the region, especially during peak snowfall. Ice accumulation in other areas could bring down trees and power lines, even if ice amounts seem modest. Once the storm departs, an influx of very cold air could lock in icy conditions and slow recovery efforts for days.

The continued northward trend in the forecast is a signal of increasing confidence, not uncertainty. As storms approach, models often converge toward stronger solutions when the atmosphere supports them. That is exactly what is happening here. This is a storm that deserves close attention and preparation, as the ingredients coming together suggest impacts that many areas do not experience often.