827
FXUS63 KLOT 030840
AFDLOT

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

.KEY MESSAGES...

- Patchy blowing/low drifting snow this morning.

- Isolated to scattered snow showers possible today with a
  point-based 20-40% chance for any measurable snow.

- Well below normal temperatures Wednesday night through the
  weekend, with the coldest period bringing minimum wind chills
  of about 10 to 20 below Thursday morning and Thursday evening.

- Additional chances for snow Saturday night-Sunday and again
  early next work week.

&&

.DISCUSSION...
Issued at 240 AM CST Wed Dec 3 2025

The gusty south/southwest winds have resulted in low drifting
snow blowing onto some roads early this morning. Added patchy
blowing snow to the grids/forecast through 15z this morning,
when winds will diminish some across the north and then across
the rest of the area early this afternoon. Trends will need to
be monitored for this end time and whether low drifting snow
develops again later this afternoon into this evening.

A strong cold front will move across the area this afternoon
into early this evening shifting southwest winds to the
northwest. There is a low chance for snow showers along and
ahead of this front and made no changes to the going forecast
pops of 20-40 percent. The HRRR is the only model suggesting
that if any precip were to develop, it could be in the form of
some patchy freezing drizzle. With confidence low on whether
there is actually precipitation today, no mention with this
forecast, but trends will need to be monitored.

No changes to the forecast or reasoning for temperatures tonight
through Friday morning. Main takeaway will be the wind chills
which will be in the -10 to -15 range overnight into Thursday
morning and again Thursday night into early Friday morning.
There may be a few areas that dip to -20 for wind chills, but
these are not expected to be prolonged or widespread. Warm air
advection early Friday morning should allow temps to level off
and then slowly rise toward daybreak Friday morning.

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 /06Z TAFS THROUGH 12Z THURSDAY/...
Issued at 1120 PM CST Tue Dec 2 2025

Key Messages:

- IFR/MVFR ceilings are expected through much of the TAF
  period.

- There is about a 40% chance for snow showers from around
  midday tomorrow through the afternoon.

- A northwesterly wind shift is expected tomorrow behind a cold
  front.


The western terminus of the IFR stratus deck over the region
continues to inch eastward. The latest model and satellite
trends suggest that the back edge of this stratus should reach
the terminals overnight and allow for a period of VFR
conditions this morning, but this still isn`t necessarily a
lock yet, particularly at the Chicago metro terminals.
Regardless, MVFR (and possibly, at times, IFR) ceilings will
likely be observed tomorrow both ahead of and behind a cold
front dropping southeastward through the region before the low
ceilings likely clear out for good tomorrow evening.

As the cold front passes through the area, it may be accompanied
by some snow showers. There is still some uncertainty over how
widespread the coverage of these snow showers will be in
northern Illinois and northwest Indiana, so the going PROB30
groups still appear to be appropriate for conveying this
possibility. If snow showers were to occur, they would likely
struggle to accumulate. However, the snowflakes would likely be
of poor quality and be capable of knocking visibilities down
even lower than what is presently advertised in the going TAFs
if snowfall rates end up being steady enough. Should also
mention that a brief period of freezing drizzle is not entirely
out of the realm of possibility either, but the chances for
this still appear to be very low on the whole (roughly a 10%
chance at any one location).

Southwesterly winds will be a bit gusty tonight as the cold
front approaches the area, but the existing snowpack and low
inversion heights should play a role in tempering the magnitude
of gusts. Winds will then shift to a northwesterly direction
behind the front this afternoon with post-frontal winds likely
retaining magnitudes similar to those of the pre-frontal winds.

Ogorek

&&

.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 until 10 AM CST this morning for Winthrop
     Harbor IL to Gary IN.

     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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