006
FXUS63 KLOT 031933
AFDLOT

Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
133 PM CST Wed Dec 3 2025

.KEY MESSAGES...

- Periods of light snow ending this evening, though flurries may
  linger into the overnight hours.

- Brief bout of very cold temperatures expected late tonight
  through Thursday night.

&&

.DISCUSSION...
Issued at 133 PM CST Wed Dec 3 2025

Through Friday Night:

Cold front is moving into our northwestern CWA early this
afternoon with areas of light snow and flurries ahead of the
front along with some transient bands of beefier snow with
larger snowflakes at times. This snow should end as cold front
moves through, with some guidance continuing to suggest there`ll
be a loss of ice nuclei and potential for some DZ/FZDZ southern
CWA early this evening.

In the wake of the front, low level cold air advection will send
temps tumbling tonight. As the column cools, cloud temps within
the lingering post frontal stratocumulus will drop as well,
dipping solidly into the range of ice being present. Pretty
common in these situations to get some very light snow or
flurries to leak out of these cold air stratocumulus clouds.
Have introduced some flurries into the grids tonight behind the
front.

Low temperatures tonight may not occur until a couple of hours
past sunrise Thursday as robust cold air advection likely
continues a slow temp fall beyond sunrise. Gusty northwest winds
will push wind chills below zero late tonight and Thursday
morning. Despite plenty of sunshine, Thursday will be very cold
with highs struggling to reach 10 above across interior northern
IL with highs into the teens in the urban heat island area of
Chicago metro and downwind of Lake Michigan across extreme
northwest Indiana. Diminishing winds Thursday afternoon will
allow wind chills to rebound to above zero during the Day
Thursday.

By early Thursday evening, guidance is in good agreement in
placing a 1028-1029mb high smack dab over northern Illinois.
Given the deep snowpack in place and clear skies, it is likely
that temps will quickly tank after the sun sets, particularly at
the typically colder locations. Wouldn`t be surprising to see
some of the typically cold spots drop to 5 to 10 below Thursday
evening, but with nearly calm winds, wind chills shouldn`t be a
factor. High pressure is progged to move east of the area
through the night Thursday, allowing southerly winds to develop
and gradually increase. The strengthening southerly flow will
send temps rising overnight, though the rise in temps will be
be partially offset by the increasing winds keeping wind chills
quite chilly.

- Izzi

Saturday through Wednesday:

There continues to be high uncertainty for precip chances in
the extended with some mention of blended chance pops from
Saturday night through the middle of next week. The one trend
that appears to be emerging is there could be a clipper parade
next week, with the potential that one or more of these pass
north of the local area, which would potentially allow temps to
moderate some. If there is precip falling with what will likely
be cold ground, some mixed precip would be possible, but way
too much uncertainty from this distance. cms

&&

.AVIATION /18Z TAFS THROUGH 00Z FRIDAY/...
Issued at 1149 AM CST Wed Dec 3 2025

Forecast concerns for the terminals...

- Period of light snow this afternoon through early evening

- 20-30% chance for some freezing drizzle to mix in mainly at
  MDW and GYY and points south

- Increasing northwest winds behind a cold front this evening
  with 20 kt gusts expected


An arctic cold front is moving through the area this morning
which has resulted in an uptick in snow showers across northeast
IL and northwest IN. While snow is expected to persist through
early evening (ending 23-01z at the terminals), accumulations
look to be rather limited with amounts generally under half an
inch expected. However, there is a chance for some freezing
drizzle to mix in this afternoon mainly at MDW and GYY and
points south. Forecast soundings continue to show a loss of
cloud ice this afternoon as the front moves through, but recent
aircraft soundings out of MDW contradict this by showing a
fairly saturated atmosphere especially in the snow growth
region. So while the freezing drizzle is becoming lower
confidence (20-30% chance) have opted keep a TEMPO group going
for now for this potential especially with some FZDZ being noted
in central IL. If freezing drizzle does materialize it would
also result in a period of IFR ceilings and visibilities.

Precipitation is expected to taper this evening as the front
exits with winds becoming northwest and breezy in its wake. Wind
gusts will likely be in the lower 20 kt range this evening
through the predawn hours Thursday due to deeper mixing. Though,
as a surface high moves overhead Thursday morning winds will
subside into the 5-10 kt range with directions gradually
becoming southwest Thursday afternoon. As for ceilings, expect
the ongoing MVFR ceilings to persist through midnight before
clouds scatter and allow VFR conditions to return through the
rest of the TAF period.

Yack

&&

.CLIMATE...
Issued at 542 PM CST Tue Dec 2 2025

Updated at 250 PM CST Tue Dec 2 2025

Here are the current record low temperatures for Thursday into
Friday this week:

Chicago           Cold High       Low
Thursday 12/4     13 (1991)      0 (1893)
Friday 12/5                      4 (2005)

Rockford          Cold High       Low
Thursday 12/4      7 (1991)     -4 (1991)
Friday 12/5                     -5 (2005)

- Izzi

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...None.
IN...None.
LM...Small Craft Advisory from 9 PM this evening to 9 AM CST
     Thursday for Winthrop Harbor IL to Gary IN.

     Small Craft Advisory until 3 PM CST Thursday for Gary to Burns
     Harbor IN-Burns Harbor to Michigan City IN.

&&

$$

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