textproduct: Chicago

KEY MESSAGES

- Milder temperatures are expected for much of the week.

DISCUSSION

Issued at 138 PM CST Mon Feb 9 2026

A low-amplitude mid-level wave near Yellowstone will quickly track eastward through tonight, crossing northern Wisconsin late tonight. Ahead of the wave late this afternoon and evening, substantial lower tropospheric WAA/isentropic ascent will encounter a rather dry airmass, with the only notable effects on sensible weather limited to plenty of mid/upper-level clouds, steady or gradually warming overnight temps, and perhaps sporadic gusts through the night. The associated cold front will cross the area in the pre-dawn hours through around sunrise, with gusty winds in store for much of the day on Tuesday. With a sharpening low-level pressure gradient from a secondary wave crossing the northern Great Lakes and a modestly favorable isallobaric wind component, NW winds may sporadically gust to 30 to 35 mph during the afternoon.

A broad and weakening ridge over the northern Great Plains on Wednesday will shift across the western Great Lakes on Thursday before another quick-moving wave traverses the area late Thursday into Thursday night. Persistent low to mid-level isentropic ascent below a somewhat stationary right entrance region of the upper-level jet will allow for gradual top-down saturation west of the area throughout the day Thursday. It remains to be seen though if there will be enough saturation to the surface this far east by Thursday evening as support from the upper-jet will begin shifting east of the area. Will maintain overall low-end chance PoPs for low QPF as snow across most of the area Thursday afternoon and evening. Any precip should end by daybreak Friday with weak ridging shifting across the area through the day.

Focus then turns to a slow-moving sub-tropical trough over the Baja of California late this week and its interaction with, or lack thereof, a faster cluster of disturbances tracking from the Pacific Northwest and British Columbia toward the far northern Great Lakes late Saturday into Sunday. Ensemble and especially deterministic guidance continues to struggle with the amount of the northward extent of precip with the stronger southern wave, primarily owing to the how much energy will be drawn into the northern wave. While there has been a southward trend in the precip shield over the past several ensemble cycles, we are still five days or more out and will need to continue to monitor future trends in the track of both waves over the coming days. In the event precip does expand well north into the area, accumulating snow will be in play late Saturday into early Sunday.

Kluber

AVIATION /00Z TAFS THROUGH 06Z WEDNESDAY/

Issued at 525 PM CST Mon Feb 9 2026

Key Messages:

- LLWS developing at 04Z this evening and continuing overnight.

- South-southwesterly winds turn northwest around daybreak Tuesday, then turn gusty by midday.

VFR conditions are anticipated through the TAF period, with only some higher level CIGs expected. South winds early this evening will turn southwest overnight. While surface wind speeds will remain in check (10-15 kt), southwest winds will increase up to 50 kt a couple thousand feet off the surface later this evening and overnight. Accordingly, LLWS is expected for several hours tonight. The only change with this forecast in the TAFs was to increase the speed in the LLWS from 45 to 50 kt. Otherwise, expect a cold front to sweep across the area around, or just after, daybreak Tuesday morning. In its wake, surface winds will turn northwesterly, with gustiness increasing (~25 kt) later in the morning and afternoon before abating with sunset early Tuesday evening.

KJB

LOT WATCHES/WARNINGS/ADVISORIES

IL...None. IN...None. LM...Small Craft Advisory from 8 AM to 6 PM CST Tuesday for Winthrop Harbor IL to Gary IN.