Area Forecast Discussion

652
FXUS63 KLSX 212039
AFDLSX

Area Forecast Discussion
National Weather Service Saint Louis MO
239 PM CST Fri Nov 21 2025

.KEY MESSAGES...

- Rain across northern Missouri and central Illinois will taper
  off this evening. Isolated showers or patchy drizzle may
  continue overnight

- This weekend continues to look dry and mild..

- Another storm system will bring rain to the area Monday and
  Monday night. Cold front will move through the region Tuesday
  night bringing temperatures down to near or slightly below
  normal for the end of the week.

&&

.SHORT TERM...  (Through Late Saturday Night)
Issued at 232 PM CST Fri Nov 21 2025

Low pressure over southeast Kansas/southwest Missouri will move east
into the Ohio Vally by early this evening.  Widespread light to
moderate rain across northeast Missouri will continue into the
evening before tapering off around midnight.  Some lingering
sprinkles or patchy drizzle will continue to be possible across much
of the area after midnight as the 850-500mb trough passes.
Northerly flow behind the system will bring cooler air into the
forecast area tonight.  Expect lows about 10 degrees cooler than
last night ranging from the mid 30s in northeast Missouri and west
central Illinois to the upper 40s across the eastern Ozarks.

The airmass behind the system isn`t particularly cold. Even with the
cooler start to the morning temperatures Saturday should rebound
into the mid to upper 50s.  However, low ceilings may not
clear/scatter until late in the morning/early afternoon across the
eastern Ozarks.  Temperatures may not warm there as much as expected
if this occurs.  The clouds should eventually clear which will
allow good radiational cooling Saturday night, leading to widespread
lows in the mid to upper 30s.  Sunday will be warmer in the upper
50s to low 60s due to the clear sky and  better insolation.

Carney

&&

.LONG TERM...  (Sunday through Next Friday)
Issued at 232 PM CST Fri Nov 21 2025

Little change to the forecast for next week.  The next mid-upper
level short wave moves into the Great Plains on Monday and through
the Mississippi Valley Monday night bringing us our next chance for
rain.  A second, stronger short wave digs into the northern
Plains/Midwest, hot on the heels of the first wave.  The general
long wave pattern in the deterministic GFS and ECMWF are very
similar, however the details are different.  The GFS develops a
strong closed low on Tuesday out of this second wave over the
Dakotas which takes the rest of the week to move across the northern
CONUS.  The EC maintains an open, negatively tilted short wave for
another 24 hours and closes off north of the Great Lakes.  These
different solutions lead to very different surface low positions,
but the surface cold front and the thrust of the colder air into our
area Tuesday night/Wednesday are still very close in both models.
Temperatures fall from the mid 50s to low 60s Monday and Tuesday to
the mid 40s to near 50 for the rest of the week.  High temperature
IQRs from the LREF are only 3-5 degrees on Wednesday and Thursday
behind the front which is pretty tight for days 5 and 6 just after a
FROPA which lends good confidence to the forecast.  Confidence
begins to wane Friday as the cold surface high moves east.
Temperature IQRs spread to around 10 degrees Friday due to stronger
return flow which would raise temperatures more quickly in some of
the ensemble solutions.

Carney

&&

.AVIATION...  (For the 18z TAFs through 18z Saturday Afternoon)
Issued at 1141 AM CST Fri Nov 21 2025

IFR flight conditions are expected to prevail across the area
through early to mid morning on Saturday. There is an area of
lifting and scattering ceilings that will try to get into central
and southeast Missouri, however it`s unclear how long the improved
conditions will last given that additional shower activity is
developing in central Missouri at this time. Low pressure will
then move across Missouri this afternoon and evening which will
shift the low level flow to the north and fill in any MVFR/VFR
spots in with IFR ceilings and potentially fog. Rain associated
with this storm system will continue across northern Missouri
into central Illinois at least through the evening hours before
tapering off around 06Z. Isolated showers or perhaps some patchy
drizzle will be possible across much of the area for the remainder
of the night. Ceilings should clear/scatter across most of the
area by 18Z Saturday.

Carney

&&

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

$$

WFO LSX

NWS LSX Office Area Forecast Discussion