640
FXUS63 KLSX 041843
AFDLSX

Area Forecast Discussion
National Weather Service Saint Louis MO
143 PM CDT Sat Oct 4 2025

.KEY MESSAGES...

- A cold front will bring cooler temperatures to the area beginning
  Tuesday.

- There is a 40 - 60% of scattered showers and thunderstorms on Monday
  and Tuesday. This is not expected to be a widespread,
  beneficial rain.


&&

.SHORT TERM...  (Through Late Sunday Night)
Issued at 142 PM CDT Sat Oct 4 2025

Deep atmospheric ridging in place will continue to stave off any
chance for showers and thunderstorms through this weekend. Low-level
cold air advection that has kept temperatures slightly cooler than
yesterday will shut off tonight, allowing tomorrow`s highs to climb
to near 90 degrees yet again. Not much will differ in terms of the
low temperature forecast, with tonight`s lows falling into the mid-
50s and low 60s and tomorrow`s falling into the low 60s.

Jaja

&&

.LONG TERM...  (Monday through Next Saturday)
Issued at 142 PM CDT Sat Oct 4 2025

A shortwave trough will ride along the northwest periphery of a mid-
level ridge spanning the southeast CONUS on Monday. Concurrently,
the ridge`s low-level reflection will push east, opening up the Mid-
Mississippi Valley to Gulf moisture. This combination will result in
an increased probability of showers and thunderstorms in southeast
Missouri and southern Illinois during the day on Monday. LREF
probabilities >0.25" of rain falling in these areas between Monday
and Tuesday have increased to 40 to 50%, about 10% higher than 24
hours ago. A caveat to this, though, is the track of the shortwave.
If the shortwave trends further southeast, so will the greatest
potential for rain.

During the same timeframe, a cold front will be approaching the area
from the northwest in response to a mid-level trough pushing through
southern Canada and the northern CONUS. This cold front is not
expected to bring much in terms of rainfall given the lack of
appreciable forcing aloft. A shortwave pushing northwest of the CWA
and increased surface moisture convergence Monday afternoon are
expected to promote scattered showers and thunderstorms, but no one
location is promised rain from the frontal passage. This is
supported by decreasing probabilities of >0.25" of rain on Monday,
with portions of northeast Missouri and west-central Illinois
peaking at 20 - 30%.

Cooler air will follow the cold front, bringing a much needed break
from the 80s to the area. Area NBM 75th percentile temperatures from
KIRK to KSAR all land in the 70s on Wednesday, with KIRK`s only
landing at 72. We begin to warm up again late in the week, but to
what degree is uncertain due to variability in the pattern at that
extent.

Jaja

&&

.AVIATION...  (For the 18z TAFs through 18z Sunday Afternoon)
Issued at 1150 AM CDT Sat Oct 4 2025

Dry and VFR conditions will prevail through the TAF period. Gusty
winds will diminish after sunset and pick up again tomorrow
afternoon from the south. Gusts of around 20 kts are expected
mainly in northeast Missouri and west-central Illinois.

Jaja

&&

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

$$

WFO LSX