textproduct: Chicago

KEY MESSAGES

- Scattered showers generally along/east of I-57 tonight.

- Chance of showers and isolated thunderstorms Saturday evening through midday Sunday.

- Above normal temperatures expected early next week.

DISCUSSION

Issued at 225 PM CDT Fri May 22 2026

Current temps are likely the highs for today, lower 70s well inland with some sunshine earlier and then 60s for much of the metro area and 50s near the lake. Cloud cover will increase this afternoon as low pressure lifts north across Indiana overnight and into southeast Michigan Saturday. There will likely be a rather sharp gradient to the showers on the west side of this system. Areas west of I-57 will be mainly dry with a period of rain expected for northwest Indiana overnight/early Saturday morning. There will be a low chance (20-30%) for showers for Cook and Lake County Illinois during the overnight hours, but most areas will remain dry. There may be a few lingering showers after daybreak near and over Lake Michigan. While an isolated thunderstorm is possible tonight, mainly east of the local area, chances are low and have no thunder mention tonight.

A lull in the precip chances is expected from late morning through mid afternoon Saturday, then a weak cold front and upper trough will approach the area by early evening with at least a slight chance (20%) of showers into the evening hours. There is some weak instability by early evening and if any showers are able to develop, then isolated thunder will be possible and opted to include slight chance thunder Saturday evening. It appears whatever develops may try to fade by mid/late evening and then redevelop overnight as the trough passes across the area. Pops increase to high chance overnight into early Sunday morning and this looks to the best chance of precipitation, which may linger through mid/late Sunday morning as it moves east. Dry weather is then expected for the rest of Sunday afternoon and into Memorial Day.

The models may be overdoing cloud cover both Saturday and Sunday but it will make for a tricky temperature forecast. Easterly winds will keep the Lake Michigan shore cooler Saturday but inland areas may warm well into the mid/upper 70s, possibly even 80 across the west. Though the lake breeze will likely be moving well inland during the late afternoon/early evening, bringing a noticeable temp drop. Once the precipitation ends on Sunday, clouds should scatter out in the afternoon, allowing highs into the upper 70s/near 80 for most of the area. A lake breeze is expected to move inland Sunday afternoon, with cooler temps near the lake. Quite a bit of uncertainty for how warm temps may rise at the Lake, before the lake breeze, but the highs will likely be brief. Highs on Monday look to reach the lower/mid 80s for most of the area, with any lake cooling confined to the Illinois shore.

Overall pattern later next week into next weekend looks blocky and likely rather dry with a trough across eastern Canada and another along the west coast. Tuesday could be another warm day with temps in the 80s with Wednesday being a transition day to this pattern with a chance of showers and perhaps a few thunderstorms, especially across the south, though still quite a bit of uncertainty. If this pattern does materialize, could be several days of northeasterly winds and cooler temps near Lake Michigan.

Not planning any changes to the beach hazard statement for the Illinois shore tonight. Its possible waves may subside faster than currently expected but will let later shifts cancel early if needed. cms

AVIATION /18Z TAFS THROUGH 00Z SUNDAY/

Issued at 1256 PM CDT Fri May 22 2026

Main Concerns:

- Lower CIGs tonight into Saturday

- Periods of showers late tonight into early Saturday at GYY - the rain may reach as far northwest as MDW and ORD

VFR conditions with at times gusty easterly winds will prevail the rest of the day today. MVFR CIGs may develop as early as this evening over northeast IL and northwest IN, highest confidence at GYY. The strongest signal for lower CIGs (and perhaps 4-6SM VSBY in BR at times) is with the closest approach of a weak surface low pressure late tonight into Saturday morning, when at least temporary IFR appears probable at the Chicago area terminals.

Rain showers on the northwest fringe of the system should be able to push into GYY (TEMPO mention there) and may clip MDW and ORD into early Saturday before exiting east. With little/no impacts expected if the rain reaches MDW and ORD, made no mention in TAFs yet. Lingering MVFR CIGs are expected erode early to mid Saturday afternoon. Northeast winds will likely briefly trend closer to due north Saturday morning, before returning to northeast near 10 kt with lake influence Saturday afternoon.

Castro

LOT WATCHES/WARNINGS/ADVISORIES

IL...Beach Hazards Statement through Saturday afternoon for ILZ006- ILZ103-ILZ104.

IN...None. LM...Small Craft Advisory until 4 AM CDT Saturday for the IL nearshore waters.