072
FXUS63 KLSX 092023
AFDLSX

Area Forecast Discussion
National Weather Service Saint Louis MO
223 PM CST Sun Nov 9 2025

.KEY MESSAGES...

- Unseasonably cold temperatures will continue through Monday
  night before a warmup takes hold through the remainder of the
  work week.


&&

.SHORT TERM...  (Through Late Monday Night)
Issued at 223 PM CST Sun Nov 9 2025

The coldest night off the young winter season is on tap as the
heart of the anomalously cold arctic air mass settles into the
Midwest. Temperatures at 850 hPa will continue to fall into the
-12 to -14C range tonight, which are well below the 1st percentile
of climatology and very near records for the date. Lows are
forecast to drop into the upper teens to mid 20s, which would be
about 15-18 degrees below normal. As has been alluded to the past
couple of days, brisk northwest winds and some clouds are the only
factors inhibiting us from threatening daily record lows for
11/10.

GOES-16 water vapor imagery currently shows another midlevel
disturbance diving southward on the western side of the longwave
trough across the eastern half of the CONUS. This feature is
forecast to continue moving south, passing just east of the
Mississippi River late tonight. Upstream observations show
widespread cloud cover and scattered flurries as far west as
Minnesota. This should translate southward late this evening -
overnight to produce some flurries in our area as well. True snow
shower activity should remain just east of our south-central
Illinois counties late tonight into Monday morning where surface
convergence is stronger along a secondary cold front.

One more unseasonably cold day is expected on Monday with highs
expected to top out in the upper 30s to near 40 degrees. A couple of
slight, but noticeable, differences tomorrow compared to today
though are weaker northwest winds and more widespread and persistent
sunshine. That means it may feel quite a bit warmer than it does
this afternoon even though the actual air temperatures in many areas
will be very similar.

A ridge of surface high pressure will move across the mid-
Mississippi Valley Monday night. Initially light/variable winds will
shift to the southwest and increase in speed overnight. This will
help yield rising temperatures late Monday night, aided by some
increase in high-level clouds as well. Lows in the low to mid
twenties are expected, but should rise at least a few degrees by
dawn on Tuesday.


Gosselin

&&

.LONG TERM...  (Tuesday through Next Sunday)
Issued at 223 PM CST Sun Nov 9 2025

(Tuesday - Friday Night)

The warmup really begins on Tuesday as low-level warm air advection
continues to strengthen. Temperatures Tuesday afternoon will be
muted at least a bit by plenty of mid/high level clouds along with
limited mixing (~875-900 hPa). Even with these limiting factors
however, highs should still reach into the 50s. Warmest locations
(upper 50s) should be across central Missouri with the coolest
readings (low 50s) in south-central Illinois.

Confidence remains very high in a return to above-normal
temperatures with dry weather for the remainder of the work week.
Ensemble guidance remains in very good agreement that mid/upper
level ridging will move eastward toward the Mississippi Valley by
late Friday. Highs are expected to climb into the 60s Wednesday and
Thursday, with low 70s favored to end the work week. After starting
the week some 15 degrees below normal, we likely will end it around
15 degrees above normal. Meanwhile, lows will also moderate through
the period. By Friday night, lows are only expected to drop into the
50s.


(Next Weekend)

Ensemble guidance diverges fairly rapidly as we head into the
weekend, mainly with the timing and strength of a mid/upper level
trough ejecting out of the southwest CONUS. The GFS/GEFS has trended
toward a faster ejection, with the trough becoming negatively tilted
across the Plains. This was a major shift compared to yesterday. The
ECMWF/EPS was a lot slower and weaker with the trough, but the new
12Z guidance has shifted a lot more toward the GFS/GEFS. There has
been a lot of model volatility in this period of time so it is hard
to trust anything, especially 6-7 days out. That being said, it may
be a period to watch for a period of widespread showers and
even some thunderstorms. There may even be at least some type of
threat for strong-severe convection in a high shear, low CAPE
environment. The CSU (based on last night`s GEFS) showed some severe
potential, but given the volatility in medium-range model guidance
outlined above, it is at least a couple of days too early to start
to become more concerned. Even the very dynamic 12Z GFS for instance
has basically no MUCAPE due to weak midlevel lapse rates, limited
low-level moisture return, and plenty of rain shower activity ahead
of the trailing cold front.


Gosselin

&&

.AVIATION...  (For the 18z TAFs through 18z Monday Afternoon)
Issued at 1102 AM CST Sun Nov 9 2025

Gusty northwest winds are the main story through Monday morning.
Gusts around 25-30 knots are expected through this afternoon
before they weaken closer to 18-20 knots tonight into Monday. Any
remaining MVFR stratocumulus should quickly lift to near 4-5 kft
AGL very early this afternoon. VFR conditions and mostly dry
weather are forecast then through the period. Some flurries are
possible overnight, but no visibility restrictions are expected.

Gosselin

&&

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

$$

WFO LSX