197
FXUS63 KLOT 230450
AFDLOT

Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
1050 PM CST Sat Feb 22 2025

.KEY MESSAGES...

- Warming trend into the middle of next week. Highs in the 40s
  and 50s Monday and Tuesday, and possibly into Wednesday.

- Chances for rain/showers Monday night (30-40%) and Wednesday
  into Wednesday night (40-50%)

&&

.DISCUSSION...
Issued at 140 PM CST Sat Feb 22 2025

Through Sunday Night:

No significant weather is expected in the short term. A shortwave
trough will ride the northwest flow aloft into the region Sunday,
but dry low levels should prevent any precipitation with just some
virga expected. Warm air advection in advance of this wave should
result in significantly milder temperatures Sunday afternoon,
mildest near/south of I-80 where little, if any, snow cover
exists.

- Izzi

Monday through Saturday:

Persistent southwesterly winds are expected through Monday with
850 mb temperatures between 5C and 8C. Surface temperatures are
expected into the 40s with a chance for the low 50s for areas
south of I-80. A dry air mass will keep things precip free
during the day. With a strengthening surface pressure gradient
ahead of the next system, winds could be breezy in the afternoon
with gusts between 20 to 25 mph.

A series of disturbances aloft will pass over the region
through the course of next week. On Monday night, a short wave
will drop out of Canada and quickly pass over northern Illinois.
While models are still bouncing around on the exact track of
the low, the consensus is for the strongest forcing to remain
just north and east of the area. However, west-southwest flow
will provide decent warm air advection across Illinois. With
colder temperatures aloft, mid level lapse rates could steepen
to around 7C/km as the wave passes over. However, even as
surface temperatures drop back into the 30s overnight, they
should remain above freezing, keeping the precip type all rain.
Other than some linger rain in northwest Indiana, most of the
system should move east of the area at or just after daybreak
for a drier Tuesday.

The warmer air mass will linger Tuesday and even into the early
part of Wednesday. High temperatures are expected to remain in
the 40s with chances for low 50s south of I-80 each day. There
is lower confidence in the exact high temperatures on Wednesday
given the cloud cover expected ahead of the next system.

There is lower confidence in the exact timing and placement of
this next system since models are still not coming into
agreement on the exact placement and track of the surface low.
Nevertheless, the next upper level wave with steeper mid level
lapse rates is expected to drop down and provide chances for
rain on Wednesday and potentially Wednesday night. Models are
suggesting that this system could potentially have a little bit
more moisture associated with it (compared to the Monday
night system). While only a few ensemble members have up to a
half an inch of rain with this system, it will be important to
monitor given the frozen ground around the area. Lastly, Winds
will flip over to the northwest behind the cold front Wednesday
evening. Models have pulled back on any wintry precip mixing in.
There is a non-zero chance a few flakes mix in on the backside
as the system exits, but the best forcing should be out ahead of
the front in the warm sector so the official forecast kept the
precip type as rain for the time being.

After a brief ridge builds in momentarily for a drier Friday,
it looks like the next wave will pass over southern Ontario
Friday night and into Saturday. Both the Euro and GFS are
keeping the center of the low north of the area, but extending
the surface trough all the way down to Central Illinois. For
now, the blend provided only a slight chance for precip (around
20 percent) which seemed fine at this range. However, with the
chances for temperatures back near the freezing mark, this
system could be the next chance for a rain/snow mix to return to
the area, although ensemble models are not showing a signal for
significant amounts.

DK

&&

.AVIATION /00Z TAFS THROUGH 06Z MONDAY/...
Issued at 1050 PM CST Sat Feb 22 2025

No forecast concerns for the terminals through Sunday night as a
broad surface high will continue to drift across the Ohio River
Valley. Therefore, winds tonight will remain light (5-10 kt) out
of the southwest before increasing Sunday morning into the 10-12
kt range. There remains a potential for occasional 15-20 kt
gusts Sunday afternoon, but due to the low frequency have left
out of TAFs for now. Otherwise, expect SCT to BKN VFR (8000 to
15000 ft) clouds through the period.

Yack

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...None.
IN...None.
LM...None.

&&

$$

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