textproduct: Chicago

KEY MESSAGES

- Another period of showers and thunderstorms expected later today into this evening. A low (5-15%) chance for severe thunderstorms continues this afternoon/early evening, primarily across central IL and IN.

- Temperatures will tumble tonight into Friday. A rain/snow mix may graze the Illinois and Wisconsin state line.

- Another period of strong winds is expected Friday, with westerly wind gusts in excess of 40 mph.

DISCUSSION

Issued at 330 AM CST Thu Feb 19 2026

A lead mid-level impulse tracking overhead has fired off a cluster of elevated storms in the vicinity of a lower-level frontal boundary across east central IL into IN early this morning. The strongest storm in this cluster recently moved across southern Benton County and parts of Warren county IN and was reported by a storm chaser to have produced hail to the size of quarters on State Rd 41 just west of Pine Village. These showers and storms are likely to fester for a couple more hours in the vicinity of this boundary in my far southern counties early this morning before waning. Otherwise, the main forecast focus quickly shifts to the storm system continuing to take shape across the central Plains early this morning.

A stout 995 mb surface low taking shape over KS, early this morning will track eastward across the Kansas City area around midday today, then lift northeastward into northern IL, while deepening to around 990 mb late this evening and overnight. A region of showers and thunderstorms is expected to develop in association with this system across eastern MO later this morning. This activity is then expected to spread east- northeastward through the day, impacting central and southern portions of IL this afternoon. A strongly sheared environment will support some severe storm potential, including supercells, with this activity today. However, our area is expected to largely remain north of these severe storms through the day.

As the main storm system begins to lift northward into our area this evening, additional elevated showers and storms are expected to develop and track north-northeastward across the area through the evening. The severe threat with these storms will be low, and primarily limited to some possibility of marginally severe hail. The systems mid-level dry slot is expected to punch northward across the area late this evening and overnight, which should result in a quick south to north transition over to low clouds and possibly some lingering drizzle and fog. This will particularly be the case across northern IL in the vicinity of the surface low track.

Finally, as the deepening surface low tracks northeastward towards western lower MI late tonight into early Friday morning, a strong cold front will surge eastward across the area. In its wake, strong pressure rises along the southwestern periphery of the surface low will drive a quick onset of strong and gusty (40+ mph) westerly winds around, or even a couple hours prior to, daybreak Friday morning. Expect these gusty winds to persist on Friday, though speeds should be on a downward trend through the afternoon. A Wind Advisory may be needed for this period.

In addition to the wind, a band of snow is expected within the systems mid-level deformation zone along the west-northwestern periphery of the low. Currently, it appears the main accumulating snow axis will remain west-northwest of our area. However, guidance continues to depict some of this activity trying to work eastward with the colder airmass into parts of northern IL before ending on Friday morning. Accordingly, some minor accumulation of an inch or less of wet snow cannot be ruled out Friday morning, mainly northwest of I-55 and north of I-80. Dry weather is slated for the afternoon hours of Friday, but temperatures will remain in the 30s with blustery conditions.

KJB

Friday night Onward:

Forecast thinking in the extended period has not changed from the previous discussion below.

This weekend, somewhat disorganized upper-level cyclonic flow (with an embedded orphaned ridge "bubble") will be in place across the Great Lakes region. With all embedded shortwaves more or less far from our area on Saturday, relatively benign weather is in store locally with seasonable highs in the mid to upper 30s, northwesterly winds of 10 to 15 mph, and partly cloudy skies.

On Sunday, several upper-level shortwaves will merge and dive southeastward across the Great Lakes. Tumbling 850mb temperatures toward the minus 10 to minus 12 range will lead to a corresponding drop in temperatures, with highs only expected to top off near the freezing mark. Increasing over-water instability will support lake effect snow showers as well, with predominantly northwesterly flow favoring northwestern Indiana. Sunday night looks like it'll be relatively chilly with a continuation of breezy northwesterly winds and overnight lows in the teens contributing to wind chills falling toward the single digits.

Lake effect snow may continue into early Monday morning before the cyclonic shear axis of the upper-level cyclonic flow slides overhead. Ensemble guidance continues to exhibit a signal for broad quasi- zonal flow to become reestablished next week allowing for a steady feed of relatively mild Pacific flow to return to the area. Accordingly, the expectation is for temperatures to warm into next week (back into the 40s). Ensemble 24-hour meteograms from the EPS and GEFS favor the next opportunity for widespread precipitation materializing sometime toward the end of next week.

Borchardt

AVIATION /12Z TAFS THROUGH 18Z FRIDAY/

Issued at 530 AM CST Thu Feb 19 2026

Key Aviation Messages for the current TAF period:

- Chances for showers and thunderstorms this afternoon/evening

- MVFR/IFR conditions expected with showers and thunderstorms

- Chances for snow at or just before daybreak tomorrow

VFR conditions are expected this morning into the early afternoon. Winds will be light and out of the northeast before becoming more easterly later this morning and increasing to around 10 knots. This wind shift is in response to a surface low pressure system that will be moving directly over the Chicago area later today. The exact track of the surface low over the area will drastically impact the wind directions, which lowers confidence slightly in what is currently in the TAF.

As the low approaches Chicago, showers and isolated thunderstorms are expected to develop late this afternoon and into this evening. Lower confidence in thunder coverage kept the mention in the TAF as a PROB30, just an adjustment to the timing based on latest guidance.

With the low passing directly over Chicago, the expectation is for cigs to lower. While there may be a dry slot and a break in the rain, cigs were updated to prevail IFR conditions for a short period prior to daybreak.

As the low moves east, another round of showers is expected to move in; however, a colder air mass will quickly follow. A short period of -RASN is possible, but a quick change over around daybreak to snow is expected with continued IFR cigs/vis expected with the snow. Winds will quickly shift from the southeast during this evening to the southwest and eventually west with the snow as the surface low moves east. A strengthening pressure gradient will sharply increase wind gusts Friday morning. There is a chance that later iterations may need to increase the expected wind gusts. Lingering flurries are possible tomorrow morning as the low gradually moves east.

DK

LOT WATCHES/WARNINGS/ADVISORIES

IL...None. IN...None. LM...Gale Watch from Friday morning through Friday afternoon for the IL and IN nearshore waters.