textproduct: Chicago

KEY MESSAGES

- Above average temperatures through Thursday.

- Scattered showers and a low chance (20%) of thunderstorms early Wednesday morning.

- Elevated fire danger Wednesday with westerly winds gusting to 30-40 mph.

- Additional rain chances Thursday night/Friday morning and possible rain/snow chances Friday night/Saturday.

DISCUSSION

Issued at 243 PM CST Mon Feb 16 2026

A pleasant afternoon is underway as a surface high to our south and east continues to promote clear skies and warm temperatures. In fact, high temperatures today (in the low to mid-60s) have already broken the record highs for today at both Chicago O'Hare and Rockford airports. In addition to the record warmth, winds are also breezy out of the southwest with gusts around 25-30 mph. Heading into this evening, the gusts will begin to subside after sunset with speeds around 5-10 mph overnight. At the same time a weak surface boundary will pivot through northern IL which will turn winds east- southeasterly. Low-level moisture is expected to pool along this boundary tonight which looks to result in another period patchy fog late tonight into Tuesday morning especially for areas north of I- 80. However, with forecast soundings showing moisture depths notably more shallow than last night suspect that any dense fog will be more limited in coverage. Therefore, have opted to just maintain a patchy fog mention in the forecast and forego any headlines at this time.

Any fog that develops tonight will erode by mid-morning on Tuesday with yet another day of above average temperatures expected. That said, skies will have more cloud cover as the trough currently off the coast of California begins to eject into the central Plains. Despite the clouds, temperatures should still top out in the mid to upper 50s for most though locations along the IL shore will be notably cooler (in the mid-40s) due to onshore winds.

The aforementioned trough will continue to lift into the Midwest Tuesday night as a surface low develops over the Dakotas and MN. This low is forecast to traverse along the surface boundary that will stall across southern WI and Lower MI tonight and lead to an area of rain showers along this boundary Tuesday night. Since the boundary should be north of us it appears that most of the widespread rainfall will miss northern IL and northwest IN, however, forecast soundings do show steep mid- level lapse rates (6-8C/km) developing overhead Tuesday night which should be sufficient to generate some scattered showers locally. Given that moisture will be a limiting factor suspect that any rain showers that materialize will likely only result in only a couple tenths of rainfall at most. Though, if the instability can be realized then a few thunderstorms could be seen and result in some localized higher rain amounts. Furthermore, with the strong kinematic field associated with the trough and surface low (bulk shear around 50-60kts) cannot completely rule out a locally stronger storm capable of gusty winds and/or small hail during this period but overall the threat for severe weather remains low (<10% chance).

The trough and surface low will begin to shift across Lower MI by Wednesday morning which will usher a pseudo dry-line across northern IL and northwest IN Wednesday morning. Not only will the dry-line bring an end to any ongoing showers and/or storms, but it will also allow dew point temperatures to tank into the low to mid-20s by Wednesday afternoon. Couple these dew points with the continued above average warmth (highs on Wednesday in the low to mid-60s) and gusty westerly winds (around 30-40+ mph), conditions look to become favorable for elevated risk of grass and brush fire spread. While there is a fairly decent agreement in guidance for the winds and low RHs to be present, fuel moistures do vary across northern IL and northwest IN due to differences in snow cover from a couple weeks ago. That said, confidence is still somewhat low as if official Red Flag Warning criteria will be met and where exactly so have opted to hold off on any fire headlines with this forecast package. However, if trends continue and confidence grows in where driest fuel moistures are then a Fire Weather Watch may need to be considered with future forecasts. Regardless, plan to use extreme caution with any burning materials on Wednesday and try to avoid any burning if possible.

The remainder of the week continues to look somewhat active as the trough currently over the Pacific northwest ejects into the west- central CONUS on Thursday and possibly phases with several shortwaves forecast to be diving out of Canada. While it looks as if Thursday will be another warm day with highs once again in the upper 50s and lower 60s, a leading shortwave trough is progged to shift into the Great Lakes Thursday night bringing another chances for precipitation with it. Given the mild temperatures forecast it appears precipitation will begin as rain Thursday night. In fact, if sufficient moisture can lift northward then a few rumbles of thunder could even be seen across portions of the area. However, as we head into the later part of Friday colder air is expected to pivot into the region behind the shortwave as the broader trough shifts over the Great Lakes. As a result, the rain is forecast to transition to either a rain-snow mix or even all snow by Saturday morning as the system progresses through. While guidance remains in decent agreement on the overall pattern, there continues to be subtle differences in the timing, intensity, and track of the shortwave and its associated surface low among various guidance members. For now saw no need to adjust the likely POPs (50-70%) offered by the NBM for Thursday night but suspect some refinement will be needed, especially with the precipitation transition timing, as we get closer. Regardless, it does appear likely that temperatures will return to more seasonable late February values this weekend with highs back in the 30s and overnight lows in the teens and 20s.

Yack

AVIATION /00Z TAFS THROUGH 06Z WEDNESDAY/

Issued at 544 PM CST Mon Feb 16 2026

Key Aviation Messages for the 00Z TAFs:

- Winds turn light east-southeast predawn as weak cold front sags into the area. Pockets of fog/low stratus possible behind the front, though confidence is low.

- Southeast winds gradually increase Tuesday afternoon, and especially Tuesday evening with gusts increasing to around 25 kts.

- Rain/shower chances increase Tuesday evening, along with MVFR cig/vis potential.

Late afternoon surface analysis depicts a weak cold frontal boundary from roughly just north of KMKE to just south of KMSN then trailing to near KALO. South of the boundary, breezy southwest winds will diminish quickly with sunset, with the weak front expected to eventually settle across northern IL after midnight tonight. Without a significant push behind the front, guidance continues to depict winds diminishing and becoming light/variable near the frontal trough, but generally settling into a light east-southeast wind across the terminals. With the weak gradient and weak frontal convergence, some pockets of low stratus/fog appear possible, though model signal remains subtle and lends low confidence in changing inherited TAF mention of 6SM BR SCT003 at MDW/ORD/DPA, and a TEMPO at RFD for 1SM BKN002 during the predawn through a little past sunrise Tuesday.

Guidance is in good agreement in a gradual increase in southeast surface winds during the day Tuesday which should help to dissipate any low stratus/fog. Winds continue to increase later in the day and into Tuesday evening, with gusts developing and increasing into the 25 kt range (and potentially stronger beyond the end of this TAF period). The approach of an upper level disturbance Tuesday night will also result in increase shower chances by late evening, with an attendant potential for MVFR cig/vis conditions.

Ratzer

LOT WATCHES/WARNINGS/ADVISORIES

IL...None. IN...None. LM...Small Craft Advisory until 6 PM CST this evening for the IL and IN nearshore waters.