textproduct: Chicago

KEY MESSAGES

- Periods of rain today, possibly mixing with light snow across northern IL.

- Very strong winds (gusting 45+ mph) Thursday night/Friday.

- Storm system Sunday with rain/snow or accumulating snow north and possibly thunderstorms (some strong?) across the south.

- Turning much colder early next week with Monday morning and Tuesday morning wind chills possibly below zero.

DISCUSSION

Issued at 255 AM CDT Wed Mar 11 2026

Low pressure will move northeast of the area this morning with a trailing cold front moving south of the cwa, which will end the threat of any strong/severe thunderstorms, though isolated lightning may still be possible through mid morning. Periods of rain are expected through early/mid afternoon and as colder air continues to spread into the region, this rain may mix with or change to light snow across northern IL, though no accumulation is currently expected. Northwest winds are expected to gust into the 30 mph range today, especially this afternoon and then winds will diminish this evening as a ridge of high pressure quickly moves across the area.

Attention then turns to a period of very strong winds expected Thursday night into Friday. Low pressure will deepen over the northern Plains Thursday into Thursday night and continue to deepen as it moves across the northern Great Lakes region Friday. The low also may slow its forward speed as it crosses the lakes. Southerly winds will begin to increase Thursday afternoon and continue increasing Thursday evening when gusts into the 45+ mph range will be possible. Winds will shift westerly behind a strong cold front Friday morning. There may be a period of gusts in the 50+ mph range with and just behind the front and then winds will slowly diminish into Friday afternoon. If these wind trends continue, a wind advisory may eventually be needed with later forecasts and its possible that if higher wind gusts are expected, there may be a need for a high wind watch. Too early for either with this forecast.

Another fast moving ridge crosses the area early Saturday morning and there has been a signal for several days for a narrow warm air advection band of snow or a rain snow mix Saturday morning, perhaps only affecting the northwest or far northern cwa. Blended guidance chance pops seem reasonable for this potential for now.

A storm system is then expected to move across the area on Sunday. There remains quite a bit of uncertainty with this system though the GFS remains consistent with a bit more southern track and perhaps more snow for the local area vs. the ECMWF which is a bit further north and less snow for the local area. If the warm sector expands far enough into the cwa, there is enough instability that thunderstorms, perhaps strong or locally severe would be possible. At the same time, much colder air is spreading into the region on the back side of this system, with precipitation likely to change over to snow, perhaps with a wintry mix during the transition Sunday afternoon into Sunday evening. The storm system is expected to deepen as it departs with strong/gusty northwest winds likely Sunday night into Monday. With low temps by Monday morning possibly in the teens, these winds would push wind chills below zero for parts of the area Monday morning. Winds will be lighter by Tuesday morning, but with air temps possibly in the single digits across the north, wind chills Tuesday morning may also be below zero for parts of the area. Temps begin to moderate by the middle of next week. cms

AVIATION /12Z TAFS THROUGH 18Z THURSDAY/

Issued at 629 AM CDT Wed Mar 11 2026

Forecast concerns include...

Ifr/Lifr cigs through this afternoon. Periods of rain through this afternoon. Chance of snow late morning into this afternoon. Gusty north/northwest winds through sunset.

Periods of rain are expected today with a lull possible mid morning. Previous model runs were suggesting another period of rain late morning into the early afternoon, but most recent guidance is trending away from this so confidence is lower for additional rain later this morning into the afternoon. If this precipitation does develop, with colder air spreading into the region, the rain may mix with snow at times, possibly changing to snow across far northern IL. Current prob mention has this potential handled for now, but trends will need to be monitored. All precipitation should be ending by late afternoon with dry conditions expected tonight into Thursday morning.

Lifr/ifr cigs are expected through early afternoon, eventually lifting to low mvfr this afternoon and scattering out this evening, from west to east.

Northerly winds to start this morning will slowly turn to the north/northwest this morning with speeds/gusts slowly increasing. Gusts into the mid/upper 20kt range are expected from mid morning through sunset. Winds will diminish this evening and turn more westerly overnight. cms

LOT WATCHES/WARNINGS/ADVISORIES

IL...None. IN...None. LM...Small Craft Advisory until 4 AM CDT Thursday for Winthrop Harbor to Northerly Is. IL.

Small Craft Advisory from 10 AM this morning to 4 AM CDT Thursday for Northerly Is. to Gary IN.

Small Craft Advisory from 10 AM this morning to 10 AM CDT Thursday for Gary to Burns Harbor IN-Burns Harbor to Michigan City IN.