788
FXUS63 KLSX 040755
AFDLSX

Area Forecast Discussion
National Weather Service Saint Louis MO
255 AM CDT Sat Oct 4 2025

.KEY MESSAGES...

- Unseasonably warm weather is expected through the weekend before temperatures
  will fall back to near normal behind a cold front on Tuesday.

- A cold front will bring a chance (30-60%) of showers and
  thunderstorms to the area Monday into Tuesday.

&&

.SHORT TERM...  (Through Late Sunday Afternoon)
Issued at 253 AM CDT Sat Oct 4 2025

Dry weather was found across Missouri and Illinois early this
morning as a large upper ridge extended from the southern Plains
into the Upper Midwest.  The dry weather is expected to continue
through tonight as the HREF is showing the ridge slowly moving east
across Missouri and Illinois.  The latest surface analysis is
depicting a high over the mid Atlantic and a low over the central
High Plains which will help increase southerly winds into the 5 to
15 mph this afternoon with some gusts to 25 mph over northeast
Missouri. Temperatures early this morning are staying mainly in the
the 60s, so with plenty of sun expect highs to climb into the middle
to upper 80s once again this afternoon.  Lows tonight will drop back
into the upper 50s and lower 60s.

Britt

&&

.LONG TERM...  (Sunday Night through Friday)
Issued at 253 AM CDT Sat Oct 4 2025

Sunday and Sunday night still look dry as the area will still be
under the influence of the deamplifying upper ridge.  Rain chances
have increased Monday, mainly over the southern and eastern CWA
where there is good agreement between between the GFS/ECWMF that an
increase in moisture transport from the Gulf will bring scattered
showers and thunderstorms.  Meanwhile, an upper trough will pass
through Upper Midwest and Great Lakes which will bring cold front
through Missouri and Illinois Monday night into Tuesday. This will
be enough to keep the chance for showers and thunderstorms going
during this timeframe.  The number of LREF members producing
precipitation Monday through Tuesday over the CWA has increased
compared to 24 hours ago to 40-70%, but the chances for seeing >0.5"
of rainfall over the area by Wednesday morning remains the same at
less than 25 percent. Then the LREF members are mainly dry Wednesday
into Thursday as a relatively flat ridge moves across the area
before the model spread increases late next week with the how
quickly the next trough will move into the Midwest.

With 850mb temperatures staying around 15C, highs are expected to
stay in the 80s through Monday before dropping back into the 70s
behind the front starting on Tuesday.  The NBM IQR at STL is only 1-
3 degrees through Monday, but then increases to 5-8 degrees through
Friday which reflects the uncertainty in the late week pattern
mentioned above.

Britt

&&

.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