textproduct: Chicago

KEY MESSAGES

- Strong and gusty winds will diminish this afternoon and evening. - Chances for light snow across the region Saturday night into Sunday which could result in a dusting/light coating in spots.

- Thereafter, accumulating lake effect snow may result in travel impacts across parts of NW Indiana (Porter County in particular) through Monday.

DISCUSSION

Issued at 148 PM CST Fri Feb 20 2026

Through Saturday:

An occluded surface low continues to slowly fill and shift east across Michigan this afternoon. In its wake, a tight pressure gradient and strong boundary layer flow (mean winds near 30 knots) will support 25 to 35 mph sustained winds and occasional gusts near 40 to 45 mph for a few more hours. As the low fills, winds will ease through the mid-late afternoon, although breezy conditions will likely persist through the night.

Cloud cover trends this evening into Saturday remain a bit uncertain. Forecast soundings and visible satellite imagery indicate the stratus layer thickness diminishes with southward extent through the CWA, and some thinning/clearing appears probable closer to our US-24 locales. While some holes may also work their way across parts of northern Illinois this evening, it seems like we'll probably end up redeveloping stratus overnight into Saturday morning, at least across northern Illinois. Have increased cloud cover a bit and have also nudged high temperatures for Saturday down a smidge. Mid and high-level cloud cover will increase during the afternoon and evening ahead of the next disturbance.

Saturday Night through Friday:

A vigorous shortwave--currently near the Four Corners Region-- will shift across our area Saturday through Sunday. While it's still not totally clear if we'll see widespread precipitation with this system due to pockets of low-mid level dry air to work through, the trend in the medium range guidance suite has been towards increased saturation and associated chances for light snow Saturday night through Sunday morning. Ascent doesn't look particularly robust, but a colder atmospheric column and surface temperatures in the 20s may support a light coating of snow in spots. Boosted PoPs a bit during this period based on the latest deterministic and ensemble output. Some lake effect/enhancement will be possible across northern Porter County during this time as well.

Attention Sunday evening through Monday will shift to the potential for accumulating lake effect snow across our northwest Indiana counties, and particularly across parts of Porter County. A secondary vort max is forecast to drop through the region Sunday evening which will shove a roughly -15 C airmass at 850 mb down the lake. With water temperatures in the upper 30s, modest lake-induced thermodynamic profiles are forecast to result, with forecasted ELs nearing 7 kft at times. While not overly significant, the progged lake thermodynamics are sufficient to support periods of moderate to even briefly heavy snowfall *if* convergence and low-level ascent ends up focusing activity into a cohesive single band. At this point, it's not clear this will be the case, with some guidance indicating a more disorganized multi-bands and less focused convergence. With this forecast package, have increased lake effect snow chances and accumulations Sunday evening through Monday across NW Indiana, and particularly over Porter County. Will need to keep an eye on this period for possible travel impacts as temperatures are expected to be in the 20s, with several inches of accumulation possible spread out over a 24+ hour period. LES activity should wind down Monday afternoon as the boundary layer rapidly dries out.

On Tuesday, a fast-moving clipper will scoot across the Upper Great Lakes. At this time, the multi-model consensus depicts the bulk of precipitation with this system occurring just north and east of our area, but close enough to justify some low precipitation chances, particularly given a southward shift in today's guidance suite. Precip type would probably be snow given progged wetbulb temperatures of upper 20s/lower 30s. Large scale forcing for ascent is forecast to be pretty intense with this system, so this is one to watch if the southward trend persists.

Breezy southwesterly winds will develop through the day on Tuesday, particularly across the southwestern half of the forecast area where temperatures may warm into the mid 40s. Still noting some potential for RH values to dip under 30 percent, but not seeing enough of a signal at this point to stray from the blended guidance which maintains some higher RH values through the afternoon. Another disturbance may bring yet another chance for precip to the region during the Wednesday - Thursday timeframe. Some indication that this could be a stronger disturbance with an attendant surface low, but noting huge spreads regarding the phasing or non-phasing of several shortwaves.

Carlaw

AVIATION /18Z TAFS THROUGH 00Z SUNDAY/

Issued at 1105 AM CST Fri Feb 20 2026

Main Items of Note:

- Westerly gusts up to 35-40 kt through mid-late this afternoon

- Prevailing 1500-2500 ft MVFR CIGs appear likely through Saturday

Westerly wind gusts will ease with time this afternoon into this evening, but likely remain at near or above 25 kt until the late evening. Thereafter, expect steady near to a bit over 10 kt west-northwest winds through Saturday. MVFR CIGs should hold through tonight, probably building down some overnight, especially outside of Chicago. Any scattering to VFR, if it happens, would probably occur sometime Saturday afternoon. Otherwise, occasional VFR flurries will be possible until about 21z this afternoon.

Castro

LOT WATCHES/WARNINGS/ADVISORIES

IL...Wind Advisory until 4 PM CST this afternoon for ILZ003-ILZ004- ILZ005-ILZ006-ILZ008-ILZ010-ILZ011-ILZ012-ILZ013-ILZ019- ILZ020-ILZ021-ILZ023-ILZ032-ILZ033-ILZ039-ILZ103-ILZ104- ILZ105-ILZ106-ILZ107-ILZ108.

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

LM...Gale Warning until 6 PM CST this evening for the IL and IN nearshore waters.