textproduct: Chicago

KEY MESSAGES

- Occasional chances for scattered rain showers will continue into next week. - Temperatures will gradually warm through Saturday before trending cooler Sunday into early next week.

DISCUSSION

Issued at 151 PM CDT Fri May 8 2026

A quasi stationary front is currently draped across the Central Plains from Topeka to Chicago. To the north of the boundary, a cooler air mass with light cumulus clouds bubbling along the northern periphery. To the south, better warm air advection allowing for showers to move from west to east south of Interstate 80. Chances for thunder cannot be completely ruled out for areas near and south of US-24 this afternoon/early evening, but any (if at all) that does occur should be isolated. Lastly, a weak lake breeze has developed. Models are suggesting that it will have a hard time moving farther inland than Cook County, but it could be a favored area for isolated showers to develop, particularly in northwest Indiana being closer located to the front.

Through the weekend, an upper level low hovering over the southern Hudson Bay will dictate the weather pattern, namely continued northwest flow over Chicago with smaller perturbations traveling around the larger upper level low. One such wave is expected to pass over the area overnight tonight. Some of the mid-level moisture might show up as returns on radar, but weak forcing and low level dry air prevented any formal mention of a chance of rain into tomorrow morning. Another wave will most likely traverse the upper level low tomorrow late morning through the afternoon sending a surface cold front over northern Illinois. Hi-res models are showing a little bit agreement on slightly better forcing with this wave to prompt a slight (15 to 24 percent) chance for rain. However, with RHs in the 30s, there is lower confidence in whether or not the rain will make it to the ground or just materialize as virga. So shower coverage may be more spotty in nature tomorrow as the wave moves southward. By Saturday night the upper level low will begin to slowly move east. Shower chances will focus Saturday evening south of I-80 and eventually move south and east. Weak upper level ridging and height rises should allow for a drier Sunday for Mother's Day. However, winds will turn northerly allowing for a cooler air mass to move in. High temperatures will go from the 70s on Saturday to just the low 60s on Sunday.

The ridging appears to be short lived as the next upper level trough may descend down out of Canada Monday night and provide the next chance for rain on Tuesday. Cooler temperatures are expected to remain through the midweek, but a potential warm stretch may be in store for the end of the work week next week.

DK

AVIATION /06Z TAFS THROUGH 12Z SUNDAY/

Issued at 1243 AM CDT Sat May 9 2026

Key messages:

- Increasingly gusty west-northwest winds this afternoon, possibly with some occasional gusts in excess of 30 kt after 19Z.

- Winds abate by sunset early evening and turn northerly as a cold front moves across the area. There is also a small potential (~15% chance) that winds briefly shift northeast at the Chicago terminals with a lake breeze early this evening.

The gusty west-northwesterly winds expected in advance of an approaching cold front this afternoon will be the primary weather story/concern across the area terminals. While gustiness up to 20 kt will begin to develop mid to late this morning as the surface gradient begins to strengthen, it appears even stronger wind gusts of at least 25-30 kt will materialize this afternoon as deep diurnal boundary layer mixing begins to top 10,000 feet AGL. Interestingly, westerly winds at this level are expected reside in the 40-45 kt range for a period mid to late this afternoon. Accordingly, the potential for mixing down this higher momentum aloft does add some concern for at least some sporadic higher gusts (perhaps around, or a bit in excess of, 35 kt) at area terminals this afternoon.

Winds will quickly abate early this evening and begin to turn northerly around sunset as the surface cold frontal passage occurs. While the winds may briefly shift more northeasterly off the lake with the front early this evening, directions should settle more northerly during the late evening and overnight hours.

The main change for the 06Z TAFs was to hit the winds a bit harder after 19Z this afternoon, going with west-northwesterly gusts up around 28 kt through the late afternoon. We also considered including a tempo group from 20-23Z for west- northwesterly wind gusts up to 35 kt to account for the some of the more sporadic strong gusts, but opted to hold off for now. This mention may need to be added to the TAFs as confidence increases.

Outside of the winds today, VFR conditions are expected, with only some higher Level CIGs around 10,000 feet possible this afternoon. A low (~20%) chance also exists for a few isolated light showers or sprinkles this afternoon.

KJB

LOT WATCHES/WARNINGS/ADVISORIES

IL...None. IN...None. LM...None.