textproduct: Chicago

KEY MESSAGES

- Cooler, breezy, and dry today with an elevated threat of wildfire spread.

- Rain chances return for Monday night into Tuesday.

- Another period of wet weather likely in the Thursday to Friday timeframe.

DISCUSSION

Issued at 242 AM CST Sun Nov 16 2025

It's a much cooler start to today following yesterday's cold frontal passage. Temperatures are hanging onto the 40s around the area as of 2 AM, but are expected to drop into the middle to upper 30s by daybreak. Highs this afternoon are forecast in the upper 40s to around 50 degrees; a stark drop from the record- breaking warmth which graced the area yesterday. The ongoing low level cold advection has recently allowed the boundary layer to open up to some stronger flow off the surface and now we're seeing rather frequent gusts between 25 and 30 mph. Forecast soundings show us decoupling some again toward sunrise causing winds to ease a bit for a period this morning. After BL mixing gets going again, we should see NW gusts between 20 and 25 mph, occasionally higher, from mid-morning through the afternoon.

High pressure will be centered just west of the Mississippi today bringing dry and sunny conditions to the region. Dewpoints early this morning are already down in the teens near and north of I-80 and the rest of the CWA is expected to follow suit by daybreak. Most recent guidance suggests dewpoints through the day will be a few to several degrees lower than previously progged. This adds confidence in an elevated threat for fire weather as we're now expecting afternoon RHs largely between 20 and 25% around the area to go along with the gusty winds and recent dry conditions. Practice extra caution with any outdoor burning today, including of leaves and other vegetation. A Special Weather Statement has been issued for the entire CWA highlighting the fire weather concerns.

Our next precip chances arrive late Monday into Tuesday as a center of low pressure passes through south-central IL. There's still a question of whether we'll see any pockets of snow or sleet out of this system, but guidance continues to favor just about all liquid. Forecast soundings exhibit a deep low level isothermal layer through the event and deterministic and ensemble guidance strongly favor largely above-freezing temperatures through this layer. If we were to see any frozen precip or a wintry mix of sorts, most likely timeframe would be toward the beginning of the event Monday evening and night as drier low level air may keep sub-freezing wet bulbs around through the night. Surface temperatures are expected to remain at least a few degrees above freezing, so we wouldn't expect noteworthy impacts out of any frozen precip. Strictly rain is heavily favored during the day on Tuesday, and guidance is in good agreement on a widespread one to two tenths of an inch of precip by the end of Tuesday afternoon.

A large synoptic system looks to impact the region late in the week and possibly bring an inch or two of rainfall to a rather large area. This system will develop in the Texas panhandle region on Wednesday and eject northeast across the Midwest through Friday. There's still some run-to-run variability on where this dynamic system will track, but model agreement is actually surprisingly good for being days five/six and considering how much this system looks to evolve across our region.

A majority of medium range camps and ensemble systems are consistently painting a large swath of 1-2" QPF around the region with this storm by the end of Friday. This is thanks to what looks to be strong dynamic forcing out ahead of the upper trough amid PWATs of 1.5 to 1.6" in the storm's warm sector; these sorts of values would not only be record-breaking against ILX RAOB climatology, but some of the highest ever sampled during the month. The last several runs of the deterministic GFS and Euro resolve the swath of highest totals either across our CWA or just missing it by no more than a few counties. This idea of the heaviest precip tracking nearby is strongly backed by ensemble guidance. Even if the axis of heaviest precip misses the local area, we could still be looking at several tenths of an inch of precip. Probs from the GEFS and ENS for at least a half an inch of rain is currently between 50 and 60% around the whole CWA. The synoptic environment will be warm enough to inhibit any frozen precip out of this system. In fact, marginally steep mid level lapse rates near the storm's warm front may even result in a few elevated thunderstorms around the region. The NBM populated the forecast with areas of slight chances for storms Thursday evening and night, and certainly couldn't argue with the potential. This is one we'll watch closely as more details come into focus.

Doom

AVIATION /18Z TAFS THROUGH 00Z TUESDAY/

Issued at 1118 AM CST Sun Nov 16 2025

There are no significant aviation weather concerns anticipated through the period.

Expect gusty northwest winds through the remainder of the day before winds abate around sunset. Skies should be generally clear with unrestricted visibility through Monday morning, then some higher level VFR cloud cover will move into the area ahead of our next approaching weather system Monday afternoon.

KJB

LOT WATCHES/WARNINGS/ADVISORIES

IL...None. IN...None. LM...Small Craft Advisory until 10 PM CST this evening for Winthrop Harbor IL to Gary IN.

Small Craft Advisory until 9 AM CST Monday for Gary to Burns Harbor IN-Burns Harbor to Michigan City IN.