textproduct: Chicago

KEY MESSAGES

- Very strong winds (gusting 45+ mph) Thursday night/Friday. Potential also exists for a short period of 60 mph gusts around daybreak Friday morning.

- 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 202 PM CDT Wed Mar 11 2026

A surface ridge axis of high pressure will slide eastward across the region tonight into early Thursday morning. This will result in a period of quiet weather tonight. On Thursday, forecast attention quickly turns to the next storm system expected to track eastward across North Dakota, while deepening to a sub 990 mb central pressure during the day. Ultimately, this low will slide eastward across the Upper Midwest and into northern Lower Michigan Thursday night into Friday morning, with a central pressure potentially dropping to an impressive 985 mb. The strength and track of this low continues to suggest that our region will be in for a period of strong gusty winds, initially from the southwest Thursday night, then from the west during the day Friday.

Confidence continues to increase that wind gusts will exceed 45 mph Thursday night and Friday. Accordingly, at least a Wind Advisory looks likely (80%+ chance) to be needed as we approach this period. However, we also have increasing concerns that a period of 55-60 mph westerly damaging wind gusts could materialize across northern IL and far northwestern IN with a cold frontal passage early Friday morning. This timing would potentially be right around, or just before, daybreak Friday morning as strong pressure rises (10mb+ per 6hr) overspread northern IL with the passage of the surface front. With this in mind, could envision a situation in which a High Wind Warning is needed for portions of far northern IL into far northwestern IN. Given we still have some time to hone in on this period of strong wind gusts, we have opted to forgo any wind headlines at this time, and will instead continue to strongly message this in our forecast graphics.

Winds will abate quickly Friday evening as a progressive area of surface high pressure shifts east across the area into early Saturday. This period of quiet weather will be short lived, however, as another potent storm system will take aim on our area this weekend. While there continues to be a good amount of uncertainty with the track and strength of this system as it moves into our area on Sunday, confidence continues to increase that it will impact our area with inclement and windy weather Sunday, followed by much colder conditions Monday.

A majority of the precipitation and winds with this weekend's system is expected Sunday into Sunday night. However, guidance continues to favor a warm air advection wing of precipitation developing across far northern portions of IL and IN Saturday into Saturday evening. Interestingly, as this initial band of precipitation develops Saturday, the column may be cold enough across far northern IL to support a period of snow, or a rain snow mix. Thereafter, depending upon the exact track the surface low takes on Sunday, the column across much of our region may warm enough to support mainly rain showers on Sunday. Thunderstorms will also be a concern along the southern flank of the low, especially along the cold front Sunday afternoon. If enough instability develops in the warm sector a few strong storms cannot be ruled out across parts of eastern IL into IN.

Much colder (winter conditions) temperatures are expected to spill into the region in the wake of this system Sunday night into Monday on gusty northwest winds (40+ mph). This will promote the change over to snow from west to east Sunday night as a mid- level deformation axis shifts across northwestern IL and WI along the west-northwestern periphery of the surface low. We will also have to monitor the potential for some accumulating snow with this into Monday morning, particularly across northwestern IL. Otherwise, the cold will be the main story on Monday, as high temperatures remain in the 20s following early morning wind chills down around 0. These cold conditions continue Tuesday, albeit will much lighter winds. Thereafter, temperatures will begin to moderate for the second half of next week. However, as the lower-level baroclinic zone begins to shift back east-northeastward near our region Tuesday night, a weak southeastward shifting mid-level impulse may induce a period of light snow near our area through early Wednesday morning.

KJB

AVIATION /18Z TAFS THROUGH 00Z FRIDAY/

Issued at 1257 PM CDT Wed Mar 11 2026

Forecast Concerns:

- Precipitation changes to snow or rain/snow mix are expected to occur this afternoon across terminals.

- Northwest wind gusts will increase this afternoon, 20-25 kts.

- Calmer weather arrives into the overnight, lingering through Thursday.

Another round of widespread precipitation currently over northeast Illinois into far northwest Indiana will continue to change from rain to snow as colder air filters across the region. RFD being on the backside of the precipitation will see snow through the afternoon, while terminals closer to metro Chicago will feature mixed precip over the next couple of hours before transitioning over to all snow as the system exits the region this evening.

Northwest winds will prevail this afternoon, with gusts in excess of 20-25 kts forecast as strong NW flow continues behind fropa from last night. Calmer weather and clearing skies move back across the region tonight through Thursday, with winds backing to the west late tonight.

Baker/Ratzer

LOT WATCHES/WARNINGS/ADVISORIES

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

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