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FXUS63 KLSX 040330
AFDLSX

Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
1030 PM CDT Fri Oct 3 2025

.KEY MESSAGES...

- The ongoing warmth will continue through early next week until a cold
  front cools us off by mid-week.

- A cold front will bring our highest chance of showers and thunderstorms
  for the next week on Monday and Tuesday (30 - 40%).


&&

.SHORT TERM...  (Through Late Saturday Night)
Issued at 238 PM CDT Fri Oct 3 2025

Scattered showers and thunderstorms continue to percolate this
afternoon due to SBCAPE of 1000 - 1500 J/kg and weak mid-level
lift. This convection has produced much needed rain for a lucky
few, with very localized MRMS estimates of 2"+ in portions of
southern Illinois so far. Unfortunately, daytime instability will
diminish with sunset, and so will our rain chances through the
weekend as mid- level ridging dominates our sensible weather.

Low-level ridging in the eastern CONUS will usher cooler and drier
850 mb air into the region tomorrow. The new advection will result
highs a few degrees cooler than today despite abundant sunshine and
a warm morning.

Jaja

&&

.LONG TERM...  (Sunday through Next Friday)
Issued at 238 PM CDT Fri Oct 3 2025

The mid-level ridge will exit east through the weekend as a deep mid-
level trough shoves into south-central Canada/the Upper Midwest by
Monday. This will allow access to Gulf moisture on Monday, which
coincides with the approach of a cold front from the northwest.
Incoming vort maxes aloft overlapping with the new-found moisture
will support at least some potential for the showers and
thunderstorms during the day in our southern and eastern counties.
That night, additional showers and thunderstorms will push into
northeast Missouri and west-central Illinois along the cold front.
Although there is high confidence in the aforementioned features
bringing us much needed rain with LREF probabilities showing a 70
to 80% chance of measurable rain. Significant rain, on the other
hand, is not likely. The same run has probabilities of 0.25"
peaking at 30% with most locations under 25%.

A rush of cold air will follow the cold front, dropping high
temperatures from widespread 80s on Monday to widespread 70s by
Wednesday. NBM highs for Wednesday are warmer than they initialized
24 hours ago, suggesting the broad trough responsible for the cold
front may not be as influential as once thought. Despite this, a
walk back into the 70s for Wednesday and Thursday will be an
appreciated break from the heat before low-level warm air advection
and subsequent warmth returns by next weekend.

Jaja

&&

.AVIATION...  (For the 06z TAFs through 06z Saturday Night)
Issued at 1028 PM CDT Fri Oct 3 2025

VFR conditions are expected throughout the 06Z TAF period.
Overnight tonight, some patchy shallow fog can`t be ruled out at
SUS and CPS. However, light be persistent southerly winds may
prevent that from happening, or perhaps carry fog away from the
terminals themselves. As such, confidence is low that fog will
actually impact these terminals, and we have opted to maintain VFR
conditions for now.

Otherwise, mostly clear skies are expected tomorrow, with breezy
southerly winds in the afternoon.

BRC

&&

.LSX WATCHES/WARNINGS/ADVISORIES...
MO...None.
IL...None.
&&

$$

WFO LSX