NWS Chicago Decision Support Briefing - Forecast

042
FXUS63 KLOT 112308
AFDLOT

Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
608 PM CDT Wed Mar 11 2026

.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 /00Z TAFS THROUGH 06Z FRIDAY/...
Issued at 608 PM CDT Wed Mar 11 2026

MVFR ceilings currently over the terminals will erode from
northwest to southeast over the next couple hours, leading to
VFR conditions through the remainder of the period. NW winds
gusting to around 20 knots at TAF issuance will diminish to
around 10 knots mid to late evening before veering W overnight
and SW/SSW on Thursday. A strong low pressure system passing
north of the terminals Thursday night will result a quick
increase in SSW winds Thursday evening. Gusts over 30 knots are
expected by the end of the TAF period (06Z Friday). Beyond the
TAF period, winds may gust over 40 knots while veering SW late
Thursday night and W/WNW through the day Friday.

Kluber

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...None.
IN...None.
LM...Small Craft Advisory until 4 AM CDT Thursday for Winthrop
Harbor IL to Gary IN.

Gale Watch from Thursday evening through Friday evening for
the IL and IN nearshore waters.

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

&&

$$

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