Saint Peters, Missouri Weather Forecast Discussion

817
FXUS63 KLSX 250803
AFDLSX
Area Forecast Discussion
National Weather Service Saint Louis MO
303 AM CDT Thu Sep 25 2025
.KEY MESSAGES...
- A prolonged stretch of dry weather is expected beginning today
  and continuing into next week. Temperatures will warm from the
  mid and upper 70s today into the 80s for the remainder of the
  period.
&&
.SHORT TERM...  (Through Late Friday Afternoon)
Issued at 300 AM CDT Thu Sep 25 2025
A long wave trough stretching from southeast Canada, through the
Mississippi Valley, into southern Texas will drift east today and
tonight, leaving  a closed low over the southeastern U.S. on Friday.
Meanwhile, the surface ridge currently over the Great Plains will
drift east over the Mississippi Valley, as upper level ridging
builds over the Midwest behind the trough.  Another cut off low
moves into the Desert Southwest behind the upper ridge forming an
omega block which locks the ridge in place over the Midwest.  This
will result in dry weather today and Friday as the ridge builds
across the region.  Should see plenty of sunshine behind the trough,
and temperatures will warm back to near normal in the mid to upper
70s today.  Above normal temperatures in the low 80s are expected
Friday as the airmass modifies.
Carney
&&
.LONG TERM...  (Friday Night through Wednesday)
Issued at 300 AM CDT Thu Sep 25 2025
Guidance shows the blocky pattern remaining in place at least
through the middle of next week.  Ridging over the
Midwest/Mississippi Valley will keep our weather dry, with a mostly
clear sky.  The mostly clear sky will result in good insolation each
day pushing high temperatures 5 to 10 degrees above normal into the
mid 80s. That same clear sky along with light winds at night will
produce excellent radiational cooling conditions.  This will allow
temperatures to fall 25 to 30 degrees overnight into the 50s in most
locations to the low 60s in the St. Louis Metro Area.
Carney
&&
.AVIATION...  (For the 06z TAFs through 06z Thursday Night)
Issued at 955 PM CDT Wed Sep 24 2025
Isolated showers have moved south of the terminals, so now expect
dry conditions the rest of the period. Fog remains likely at JEF
and also now at SUS with MVFR (possible IFR) visibilities between
10-13Z. Dry and VFR conditions are expected thereafter with light
winds.
Britt
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...None.
IL...None.
&&
$$
WFO LSX

NWS LSX Office Area Forecast Discussion