049
FXUS63 KLSX 102051
AFDLSX

Area Forecast Discussion
National Weather Service Saint Louis MO
351 PM CDT Sun Aug 10 2025

.KEY MESSAGES...

- There will be a chance of showers and thunderstorms through at
  least the middle of the week before the chance decreases towards
  next weekend.

- Temperatures will remain near or just above normal for the
  middle of August.


&&

.SHORT TERM...  (Through Late Monday Night)
Issued at 348 PM CDT Sun Aug 10 2025

I have dropped the Flood Watch over the northern CWA where I no
longer expect widespread thunderstorms producing heavy rainfall.
There will still be a chance of showers and thunderstorms over
northeast Missouri and west central Missouri through tomorrow
morning, however the threat for flash flooding has decreased in this
area.

A band of showers and thunderstorms continues to develop across
eastern Missouri into far southwest Illinois this afternoon in a
band of low level moisture convergence in an area of MUCAPES of 2000-
3000+ J/kg with little CINH.  The RAP is showing this area of
convergence will weaken in the next few hours which should cause the
area to also gradually diminish by early this evening.  Until then,
there will continue to be the threat of one or two severe
thunderstorms capable of producing damaging winds and also locally
heavy rainfall given PWATS near 2" and slow storm movement.
Additional thunderstorms are expected to develop this evening over
central Missouri along the eastern edge of the low level jet.  This
axis will stay to our west keeping the heaviest precipitation and
best chances for rain to our west into tomorrow. There will be
additional chances for showers and thunderstorms to redevelop over
the area during daytime heating on Monday afternoon when MLCAPES
climb into the 1500-2500+ J/kg range.

Highs on Monday will range from the low to mid 80s over northeast
Missouri and west central Illinois to around 90 in around from I-70
southward.

Britt

&&

.LONG TERM...  (Tuesday through Next Sunday)
Issued at 348 PM CDT Sun Aug 10 2025

There has not been much change in the thinking in the forecast for
this week as the LREF is showing the upper trough lifting into the
Great Lakes by midweek with the pattern becoming more amplified
toward the weekend as a upper high builds over the southern CONUS.
The trough will initially be supportive of shower and
thunderstorm development, particularly during afternoon and early
evening hours Tuesday and Wednesday before chances lower into next
weekend as upper heights rise over the area. We will be in a
highly unstable, weakly sheared atmosphere in the warm sector, and
available guidance (CIPS, CSU, and ML) are all pointing to low
chances for severe weather indicating any strong storms may only
produce isolated gusty winds. There still may be some locally
heavy rainfall into at least Tuesday as the LREF is showing PWATS
around 1.75".

High temperatures across the area this week will range from the mid
80s to the mid 90s with a slow climb in temperatures toward the
weekend as the upper high begins to build over the area.  Heat
indexes will also start to climb toward the end of the week with
some areas reaching around 100 degrees by Friday and Saturday.

Britt

&&

.AVIATION...  (For the 18z TAFs through 18z Monday Afternoon)
Issued at 1242 PM CDT Sun Aug 10 2025

There will be a chance for showers and thunderstorms throughout
the period at the terminals. The most likely time will be
between 19-22Z at UIN, 18-21Z and 09-12Z at COU/JEF, and through
19Z this afternoon at the STL area terminals. Any of the heavier
showers and thunderstorms will be capable producing MVFR/possible
IFR ceilings and visibilities and possible winds gusts over 35
knots. Winds will generally be out of the south at 10 knots or
less outside of thunderstorms.

Britt

&&

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

$$

WFO LSX