791
FXUS63 KLOT 191956
AFDLOT

Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
156 PM CST Wed Nov 19 2025

.KEY MESSAGES...

- Plenty of cloud cover expected through Thursday and possibly
  through Friday.

- Dry and seasonably warm this weekend.

&&

.DISCUSSION...
Issued at 156 PM CST Wed Nov 19 2025

A deamplifying mid-level ridge centered along the entire
Mississippi River Valley will give way to a low-amplitude trough
brushing the northern Great Lakes Thursday through Friday.
Meanwhile, a trough axis crossing California will pick up an
elongated upper-level (Great Basin to Baja of California) and
bring a highly sheared resultant trough across the Ohio River
Valley late Friday into Saturday.

With a surface ridge passing just east of the area tonight and
seasonably weak surface low passing well to the south Friday
night, the area will remain in a period of generally weak flow.
This has resulted in stratus blanketing the area today. With WAA
within the low-level cloud layer and a subtle low/mid-level
wave crossing far northern IL tonight, little change in the
cloud cover is expected through at least tonight. An inversion
initially around 5kft will also support a sufficiently deep
saturated layer for patches of drizzle this evening into the
early overnight hours, particularly west of the Chicago metro.
Lowering inversion heights behind the wave will begin to
suppress cloud depths overnight and especially Thursday. While
the stratus layer will ultimately thin on Thursday, the low sun
angle and lack of any low-level drying (dew points actually
steady or rising) may limit local erosion of the stratus. Have
continued the downward trend in forecast temps, with stratus
most likely to continue over northern Illinois and possibly the
entire forecast area through much of the day.

Guidance continues to come into more agreement that much of the
precip associated with the ragged system over the Ohio River
Valley will remain focused south of the forecast area late
Thursday through Friday night. Blended guidance has started to
sharpen the PoP gradient while also shifting the gradient
southward. Modest low-level drying will further lower precip
potential into at least Friday morning, but isolated mid-level
rain showers may still expand well northward into the forecast
area Friday afternoon and evening.

High pressure will bring quiet weather conditions to the area
for the upcoming weekend. Expect mostly clear skies and
seasonably warm conditions, with highs in the 50s.

A powerful trough west of British Columbia is progged to
transition to an upper-level low over the southwest CONUS before
ejecting across the Midwest next Tuesday. Given the inherent
complexities of this evolution, confidence in the forecast this
far out remains low. However, unsettled weather with period of
showers and perhaps some storms does appear likely in the
general region on Tuesday.

Kluber

&&

.AVIATION /18Z TAFS THROUGH 00Z FRIDAY/...
Issued at 1125 AM CST Wed Nov 19 2025

The key aviation messages are:

- Prevailing MVFR cigs likely through the TAF period

- Potential for periods of BR and/or -DZ, greatest INVOF RFD,
  but could extend east to the Chicago area sites tonight into
  Thursday morning

Widespread MVFR stratus appears likely to remain in place
through the TAF period. Some vsby restrictions due to BR and or
some light -DZ are possible at RFD later this afternoon. The
main signal for -DZ/BR is later this evening, overnight, and
into early Thursday morning. Have introduced a TEMPO group for
IFR cigs and vsbys at RFD to cover the period of greatest signal
for flight category reductions, but it`s conceivable IFR
conditions extend beyond what`s advertised in the current TAF.

Confidence in IFR remains too low at this time to justify an
inclusion at the Chicago-area terminals at this time. With
moisture expected to increase through the day on Thursday, vsbys
may end up prevailing in the 5-7 sm range into the afternoon.

Light/variable to southeasterly winds will become southerly and
eventually southwesterly late tonight.

Carlaw

&&

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

&&

$$

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