244
FXUS63 KLOT 200905
AFDLOT

Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
305 AM CST Thu Nov 20 2025

.KEY MESSAGES...

- Patchy drizzle and fog will linger through the early morning
  hours today, with cloud cover hanging on through tonight.

- Some light rain is possible Friday, especially south of I-80.

&&

.DISCUSSION...
Issued at 305 AM CST Thu Nov 20 2025

Thick stratus deck currently blankets the region with recent
ACARs sounding from MDW and KLOT VWP both pointing toward 5-6kft
thick stratus deck. Some modest shear within the cloud bearing
layer is resulting in some areas of light drizzle. CIGs have
been slowly building down overnight with some patchy fog. No
reason to think that patchy drizzle and fog won`t linger past
sunrise. By later this morning, Bufkit soundings show the depth
of the stratus decreasing, which could lead to a lessening of
the drizzle threat.

Stratus deck should result in temps only inching up 2-4F degrees
this afternoon and have continued the trend of the previous few
forecasts of lowering high temps for today. Interestingly, NAM
and RAP forecast soundings in particular, show stratus depth
increasing again later this afternoon into this evening in
response to glancing blow of ascent from a shortwave passing to
our north. It is plausible this could lead to another round of
patchy drizzle very late this afternoon into this evening,
especially northern CWA. Shallow depth to moisture should keep
chances of measurable precipitation low, but another bout of
some drizzle certainly seems plausible.

Vigorous upper low seen on water vapor imagery over southern AZ
early this morning is progged to move northeast to the central
high Plains by early Friday morning, then quickly shear out as
it races eastward toward the mid-Mississippi Valley Friday into
Friday night. Rain associated with this system will likely light
up over Missouri and downstate IL tonight, likely remaining
south of our CWA. By Friday, some of this rain could lift north
into mainly southern portions of the CWA. Dry air advection in
the wake of the weak cold front will likely hinder the northward
progression of the rain shield Friday, keeping the best rain
chances south of I-80. The drier air should scour out the
stratus north of I-80, but extensive mid-high level cloudiness
will probably keep our chances at seeing the sun limited.

Dry weather is expected over the weekend into at least Monday
with moderating temperatures. By Sunday and Monday, highs should
get well into the 50s with a few 60 degree readings possible if
high cloudiness isn`t too extensive in advance of the next
system. Medium range guidance continues to advertise a big
trough moving across the country Tuesday through Thanksgiving
next week. Big troughs like this often move out slower than
progged this far out, so confidence in timing is low, especially
given we`re looking a split flow pattern with the potential for
some phasing. Given the complexities of next week`s pattern, saw
no reason to deviate from NBM which advertises increasing precip
chances and eventually colder temps behind the trough.

- Izzi

&&

.AVIATION /00Z TAFS THROUGH 06Z FRIDAY/...
Issued at 537 PM CST Wed Nov 19 2025

Forecast concerns include...

Low mvfr cigs through the period.
Areas of ifr cigs/vis and drizzle this evening.

Prevailing low mvfr cigs are expected everywhere through at
least Thursday afternoon when some breaks in the cloud cover are
possible. Some of the guidance suggests the mvfr cigs may
scatter out Thursday afternoon but confidence is low.

For this evening, ifr cigs and patches of lifr cigs along with
ifr vis have developed across parts of north central and central
IL, along with patchy drizzle. These are likely to continue
through much of this evening though ifr cigs are likely to
continue through mid morning for RFD and possibly DPA. Ifr cigs
are possible for the rest of the terminals overnight into
Thursday morning, but confidence is too low for mention with
this forecast.

Light southeast winds will become light south/southwest
overnight and then increase in speeds later Thursday morning,
possibly to 10kts at times, with speeds then diminishing some
after sunset Thursday evening. Directions will turn more to the
west/southwest Thursday evening. cms

&&

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

&&

$$

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