textproduct: Chicago

KEY MESSAGES

- Some slushy snow accumulations (not likely on pavement) are possible mainly west of the Fox Valley this morning.

- Wind Advisories are in effect today for strong westerly winds with gusts 45+ mph. - Additional shots of snow late Saturday night into Monday, mainly near the lake in NW Indiana with some minor accumulations possible.

DISCUSSION

Issued at 327 AM CST Fri Feb 20 2026

Early morning surface analysis places 992 mb low pressure over northwest IL, with an occluding cold front extending southeast bisecting the cwa and lifting northeast. Blustery southwest winds gusting 40-45 mph were developing behind the front, advecting colder low-mid 30 degree temperatures into the forecast area. These gusty 40-45 mph winds will continue to spread northeast across the area early this morning, becoming more westerly and slowly easing to 35-40 mph later this afternoon. This generally aligns with current Wind Advisory headlines, and no changes are planned. Blustery west winds will persist this evening, but will continue to slowly diminish overnight.

Scattered showers and thunderstorms had moved north/east of the area overnight, with the area currently precipitation-free within the synoptic dry slot associated with the deep upper level low stacked above the surface circulation. Regional radar presentation depicts a trailing region of deformation precipitation currently extending from central WI into central and eastern IA, and this is expected to generally lift northeast this morning, while the southern periphery wraps eastward into northern IL. This is progged to spread precipitation back into the area toward daybreak, Forecast soundings initially indicate shallow moisture profiles to warm to support much ice nucleation, though moisture does deepen with time into mid- morning to support a change from intermittent light rain/drizzle to snow. Moisture/thermal profiles over our northwestern cwa (including Rockford) appear most likely to support a period of light snow, though of relatively poor- quality with the best moisture located below the DGZ. Combined with surface temps in the low-mid 30s, would expect little impact on paved surfaces, though accumulations of less than an inch on grassy surfaces are possible. Farther east/south, shorter duration of deeper moisture suggests little to no significant accumulation is likely, and precipitation should diminish with eastward extent and gradually dissipate by midday/ early afternoon. Mostly cloudy skies will linger, especially along/north of I-80 this afternoon, with temperatures remaining in the low to mid 30s in most areas within the blustery cold advection regime.

Rising heights in the wake of the departing upper low, combined with cold, dry low-level advection will make for quiet weather conditions tonight with skies eventually becoming partly cloudy and overnight lows in the low to mid 20s. Breezy northwest winds with gust into the 20-25 mph range will linger Saturday, while temperatures only warming into the mid to upper 30s.

Ratzer

Saturday night through Thursday:

A series of shortwaves embedded within broad cyclonic flow aloft will propagate southward from Wisconsin and Michigan on Sunday and Sunday evening. In turn, mid and upper-level winds will turn northwesterly and colder air will spill southward. Some increase in boundary layer moisture, coincident with steepening lapse rates may support the development of some snow showers, primarily downwind of Lake Michigan into parts of northwest Indiana. With 850 mb temperatures forecast near -15 C, lake effect parameters don't appear overly significant, but sufficient to sustain accumulating snow showers with lake- induced ELs progged near 6-7 kft. Generally NNW to NW boundary layer flow looks to focus the bulk of this activity across parts of Porter County at this time. That said, there are some indications pointing to the flow veering more northerly Sunday night into Monday which could focus additional lake effect snow potential a bit farther westward.

Surface high pressure will transit the region through Monday night with southwesterly return flow redeveloping on Tuesday. Strong/gusty south-southwest winds will start to push a warmer airmass overhead, although a lingering stout inversion will likely limit the degree of mixing we see Tuesday afternoon. Still, medium range guidance suggests we may mix deep enough to drive 30-40 mph gusts and temperatures warming into the low to maybe mid 40s across our far southwest (cooler towards the northeast). The ECMWF (and recent runs of the GFS) remain a bit warmer than the rest of the guidance suite, and has RHs falling into the 20-25 percent range Tuesday afternoon. If this materializes, we'd have to keep an eye on another heightened grass fire threat, although the latest multi-model consensus suggests slightly cooler temperatures and higher surface dew points and relative humidity.

Active split flow pattern will continue through the middle/end of next week with the next chances for precipitation in the Wednesday/Thursday timeframe.

Carlaw/Ratzer

AVIATION /12Z TAFS THROUGH 18Z SATURDAY/

Issued at 532 AM CST Fri Feb 20 2026

Key messages for the 12Z TAF period:

* Gusty westerly winds this morning and afternoon to around 40 kt

* A period of snow showers and flurries this morning with associated vsby reductions possible, especially at RFD

* MVFR to IFR cigs this morning and afternoon. Low confidence on a return to VFR

Winds have already begun to pick up for the day with ORD and MDW having both reported gusts to 39 kt prior to dawn. Gusts to around 40 kt will persist through the morning before gradually subsiding during the afternoon and evening. Direction will veer from SW to W this morning.

MVFR to IFR cigs have settled over the terminals early this morning. The Chicago sites may drop to IFR shortly after sunrise. Most of the daytime is favored beneath MVFR. Timing on a return to VFR is low confidence; a number of models suggest late afternoon although others say MVFR may hang on into tonight. Conceptually, the earlier solution appears more likely.

A push of light snow showers is anticipated this morning. Snow will begin at RFD around or shortly after 12Z and closer to 14Z in Chicago. Leading up to the onset of snow, periods of drizzle may materialize and bring vsbys down to MVFR. At RFD, IFR vsbys and a few tenths of an inch of accumulation will be possible. Lesser impacts are expected into Chicagoland with MVFR vsbys possible and perhaps a dusting left on cooler surfaces. Snow showers will end by late morning with flurries possibly lingering into the afternoon, especially at RFD.

Doom

LOT WATCHES/WARNINGS/ADVISORIES

IL...Wind Advisory until 4 PM CST this afternoon for ILZ003-ILZ004- ILZ005-ILZ006-ILZ008-ILZ010-ILZ011-ILZ012-ILZ013-ILZ103- ILZ104.

Wind Advisory until 4 PM CST this afternoon for ILZ019-ILZ020- ILZ021-ILZ023-ILZ032-ILZ033-ILZ039-ILZ105-ILZ106-ILZ107- ILZ108.

IN...Wind Advisory until 4 PM CST /5 PM EST/ this afternoon for INZ001-INZ002-INZ010-INZ011-INZ019.

LM...Small Craft Advisory until 6 AM CST early this morning for Winthrop Harbor to Northerly Is. IL.

Gale Warning until 6 PM CST this evening for Winthrop Harbor to Northerly Is. IL.

Gale Warning until 6 PM CST this evening for Northerly Is. IL to Michigan City IN.