835
FXUS63 KLSX 221021
AFDLSX

Area Forecast Discussion
National Weather Service St Louis MO
521 AM CDT Wed Jul 22 2026

.KEY MESSAGES...

- Cooler and less humid weather is expected through Friday.

- The next chance for rain will be late Thursday night into Saturday
  as an upper level storm system moves across the area.

&&

.SHORT TERM /THROUGH THURSDAY/...
Issued at 245 AM CDT Wed Jul 22 2026

Temperatures are already dropping into the 60s and 70s early this
morning as northerly winds advect cooler and less humid air into the
area early this morning.  The low level flow will continue through
tonight as the HREF is showing a surface high moving from the Upper
Midwest into the Great Lakes.  Mainly dry weather is expected the
through Thursday with the dry low level flow underneath northwest
flow aloft.  With only fair weather cumulus today and tomorrow,
highs will only range from the upper 70s over parts of eastern CWA
to mid 80s over central and southeast Missouri.

&&

.LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/...
Issued at 245 AM CDT Wed Jul 22 2026

The GFS/ECMWF is showing an upper ridge building over the western
CONUS Thursday into Friday which keeps northwest upper flow over
Missouri and Illinois.  Showers and thunderstorm chances will
increase over the area beginning late Thursday night and continues
into Saturday with the NBM/LREF showing the highest chances (40-70%)
on Friday morning when the low level jet will be focused over the
area. There will also be a upper trough that will move across
Missouri and Illinois that both the determistic models and the LREF
is showing timing differences which keeps PoPs in the forecast into
Saturday.   This spread in timing will decrease in coming days as
the models come into the better agreement.  The LREF is showing
PWATS around 2" and WPC is highlighting most of the Missouri
counties in slight risk for excessive rainfall on Friday. The LREF
then shows the upper ridge shifting east and building over the
central CONUS.  This keeps the area mainly dry from late weekend
through the first part of next week.

Temperatures on Friday will remain cool with clouds, the chance of
rain, and the cool surface flow.  Highs will begin to warm back
above normal by Sunday as a warm front moves back through the area
and 850mb temperatures climb back above 20C.

&&

.AVIATION /06Z TAFS THROUGH 12Z THURSDAY/...
Issued at 519 AM CDT Wed Jul 22 2026

Dry and VFR conditions are expected through the period.
Northwest winds are expected to veer to the northeast and remain
less than 10 knots.


&&

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

&&

$$

SHORT TERM...Britt
LONG TERM...Britt
AVIATION...Britt