213
FXUS63 KLSX 091121
AFDLSX

Area Forecast Discussion
National Weather Service St Louis MO
621 AM CDT Fri Oct 9 2026

.KEY MESSAGES...

- Near-record temperatures are forecast this afternoon and Monday.

- The remnants of Tropical Cyclone Isaias will bring slightly
  "cooler" temperatures over the weekend due to clouds, as well
  as chances of light rain in southeast Missouri and southwest
  Illinois on Saturday and Saturday night.

&&

.SHORT TERM /THROUGH SATURDAY NIGHT/...
Issued at 327 AM CDT Fri Oct 9 2026

The latest surface analysis is showing a low over Nebraska with a
warm front extending southeastward into western Missouri and
northern Arkansas early this morning.  There is a complex of showers
and thunderstorms moving southeast across Iowa well to the northeast
of the this front that is expected to miss the CWA just to the north
and east.  This will leave the CWA dry through early tomorrow as the
HREF is showing a upper high moving across the CWA through tonight.
This will change by late on Saturday as the remnants of Hurricane
Isaias will move north and begin to affect the area.  While the
official track from NHC and model guidance has continued to shift
the track eastward, 30-40% of the LREF members continue to show rain
at Farmington and 50-60% at Salem, IL on the northwest periphery of
the track Saturday afternoon into Saturday night.  With the trend
being to the east, it looks like the rain chances will be mainly
confined to southeast Missouri into southwest Illinois.

The aforementioned front is forecast to move northeast today which
should allow high temperatures to be a few degrees warmer than
yesterday.  With almost full sunshine and 850mb temperatures
climbing to around 17C, expect high temperatures to be in the
middle 80s to around 90 degrees which will be in record
territory at all three climate sites (see climate section).
Highs on Saturday will not be as warm with the expected clouds
and rain chances in the southeast associated with the remnants
of Isaias.

&&

.LONG TERM /SUNDAY THROUGH THURSDAY/...
Issued at 327 AM CDT Fri Oct 9 2026

Dry weather is expected to return Sunday into Monday as an
upper ridge builds back into the area. Then the chances for
showers and a few thunderstorms will increase by mid to late
next week with moisture increasing over the area as early as
Tuesday. Cluster analysis is showing several different scenarios
on how quickly the ridge will move off to the east which will
allow a western CONUS ridge and an attendant front to move east
through the Midwest. At this point, the LREF/NBM members are
producing the greatest coverage of rain on Thursday.

Highs will warm back up into record territory on Monday as 850mb
temperatures climb to around 20C with full sunshine and
southwesterly surface winds. There is rather high confidence in
this given the NBM 25th/75th percentiles on Monday at STL are
only 5 degrees. By Tuesday, model guidance is showing a cold
front moving south into the area with the NBM showing a larger
spread in highs from north to south across the area than on
Monday. With this said, highs are still forecast to climb to
near 90 degrees ahead of the front on Tuesday. It will be cooler
behind the front on Wednesday and Thursday with highs in the
70s and 80s.

&&

.AVIATION /12Z TAFS THROUGH 18Z SATURDAY/...
Issued at 618 AM CDT Fri Oct 9 2026

Mainly dry and VFR conditions are expected through the period.
There remains a low chance (<30%) for fog with MVFR visibilities to
develop at SUS/CPS through 13Z. Otherwise, Light and variable
winds are expected to turn out of the south to southeast at less
than 10 knots.

&&

.CLIMATE...
Issued at 219 PM CDT Wed Oct 7 2026

Record high temperatures are possible between Friday 10/9 and Monday
10/12. Here are current records at each of our 3 official climate
stations:

                    KSTL            KCOU            KUIN
Friday 10/9       89/1938         91/1893         89/1938
Saturday 10/10    92/1963         92/1963         89/1963
Sunday 10/11      94/1963         89/1962         88/1962
Monday 10/12      90/2024         94/1899         88/1975

&&

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

&&

$$

SHORT TERM...Britt
LONG TERM...Britt
AVIATION...Jaja
CLIMATE...Gosselin