textproduct: Chicago

KEY MESSAGES

- Briefly warmer (70s) and windy on Tuesday with the potential for showers and storms.

- Otherwise cooler (60s) and dry conditions are favored through Thursday before a warm-up commences heading into the weekend with additional shower/storm chances.

DISCUSSION

Issued at 247 PM CDT Sun May 10 2026

Cooler conditions prevail for Mother's Day today with temperatures in the 50s near the lakeshore and lower to mid 60s inland. A convergence axis has set up on the western side of Chicago extending well into northwest Indiana where the drier northwest flow meets the lake modified airmass and associated northeast to east winds. This stalled lake breeze boundary will eventually progress a bit farther inland later this afternoon into early evening.

Cloud cover associated with an axis of mid-level moisture sagging south across the area through this evening and overnight may slow our cooling initially before clouds clear out toward daybreak. Given the cooler regional airmass in place, still anticipate temperatures will fall into the upper 30s across interior northern Illinois late tonight (40s expected elsewhere). Meanwhile a surface trough axis/lake enhanced boundary will dive south across the area late tonight into early Monday morning. Increased low-level flow in the wake of this feature may produce sufficient mixing of the near surface layer to limit frost coverage in those areas, so have opted to hold off on a Frost Advisory and maintain "patchy" wording near the WI/IL state line with this update.

Cooler temperatures will continue into Monday as the center of high pressure sets up to our north leading to continued onshore flow from Lake Michigan (50s near the lake and 60s farther inland). A reinforcing lake breeze will then progress well inland late in the afternoon through the evening followed by temperatures falling steadily in its wake.

We continue to monitor the potential for showers and storms on Tuesday associated with a trough expected to dive across the region. Warm and moist advection ahead of this feature will allow temperatures to warm well into the 70s across the area paired with strong southwesterly winds gusting up to 35-40+ mph during the afternoon. A north to south oriented axis of warm advective showers may try to brush northern Illinois early in the morning on Tuesday ahead of the main system and associated cold front. Additional showers and storms may then develop along the front and move across the area into the afternoon and evening. Marginal mid-level lapse rates and low- level moisture will limit the overall strong to severe potential here locally but will have to monitor model trends closely given strong deep layer shear in place. Will have to keep an eye out for the potential for locally stronger storms given sufficient shear in place in spite of marginal mid-level lapse rates and instability. The strong southwesterly winds may also lead to some blowing dust concerns, especially in rural and open areas near recently worked over farm fields.

Temperatures briefly cool down once more in the wake of Tuesday's cold front, with high temperatures on Wednesday back in the 60s. We then gradually warm up each day through the end of the week as upper level ridging builds across the central CONUS into the Upper Midwest by the weekend. The degree of warmth remains somewhat in question given the potential for a closed mid-level low feature moderating things a bit. Blended guidance has accordingly trended a bit cooler with the latest update, with forecast highs in the mid 70s to lower 80s over the weekend.

Petr

AVIATION /18Z TAFS THROUGH 00Z TUESDAY/

Issued at 1226 PM CDT Sun May 10 2026

Key Aviation Messages for the current TAF period:

- A lake breeze is expected to switch prevailing winds from northwest to northeast this afternoon. Low confidence in the exact timing of the wind shift at Chicago terminals.

VFR cumulus clouds have bubbled up across northern Illinois, but the TAFs will remain VFR through the forecast window. The primary impact will be wind directions. Obs in the interior part of Illinois mostly display northwest winds with occasional gusts up to 20 knots. However, the TORD radar is showing a weak lake breeze moving through Cook County with surface observations out of the northeast. There is lower confidence in the exact timing of wind directions flipping from northwest to northeast and whether or not the northwest winds will help the lake breeze stall. The lake breeze will be monitored closely through the afternoon for any amendments needed to adjust timing.

Once the lake breeze passes, winds are expected to remain east- northeast through the rest of the forecast package. Winds are expected to favor more easterly this evening to overnight, and then favor more northeasterly prior to daybreak tomorrow as a weak front moves down the lake increasing winds to just over 10 knots. There is a little slug of mid level moisture out ahead of this front. While a brief sprinkle is possible, there is a better chance in it remaining virga; thus, the TAFs were kept dry.

DK

LOT WATCHES/WARNINGS/ADVISORIES

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