489
FXUS63 KLSX 090445
AFDLSX

Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
1045 PM CST Sat Nov 8 2025

.KEY MESSAGES...

- The coldest temperatures so far this season will move in
  overnight tonight and last through Tuesday morning. A warming
  trend starts Tuesday and continues through the end of the week.


&&

.SHORT TERM...  (Through Late Sunday Night)
Issued at 236 PM CST Sat Nov 8 2025

A weak surface low was nearing KIRK at 2000 UTC, with an
attendant cold front draped to the southwest. This front will
sweep eastward across the CWA quickly through this evening, with
winds shifting to the northwest. Some gusts of 25-30+ mph are
expected in the 1-2 hours after the frontal passage. Some
sprinkles/light rain showers are also possible, though measurable
rainfall should be tough to come by. Model soundings show very dry
air below 10 kft AGL. The duration of the low-level moisture
advection in any given location is also quite short, maybe 1-2
hours. That doesn`t allow enough time for the column to saturate
top-down. Therefore, mostly sprinkles are expected across the area
through the afternoon. By early evening, surface convergence
strengthens across southeast Missouri/southwest Illinois. This is
where scattered showers are possible before midnight along with an
isolated rumble of thunder. Scattered shower activity is also
expected this afternoon/early evening across far northern sections
of the area along/just north of the surface low track.

Temperatures will gradually fall behind the front through the night
and into Sunday morning as low-level cold air advection intensifies.
Weak midlevel frontogenesis, cyclonic flow aloft, and increasing
diurnal instability all suggest the chance of flurries through the
day on Sunday. Though surface temperatures will be in the mid 30s
for the most part during the day, temperatures aloft are very cold
and wetbulb temperatures in the 20s. Therefore, changed any sprinkle
wording over to flurries even where it was warmer. A secondary
midlevel disturbance moves across central/eastern Illinois overnight
Sunday night. This disturbance may also yield some snow flurry
activity along/east of the Mississippi River.

Highs on Sunday were cooled several degrees from the previous
forecast. The incoming air mass is very impressive for early/mid
November as 850-hPa temperatures crash below -10C. Those readings
are below the 1st percentile of climatology. It is very difficult to
see much, if any, warming even with some partial sunshine Sunday
afternoon given the strength of this incoming air mass and the
persistently strong low-level cold air advection. Highs should stay
in the 30s across the entire area. Parts of southeast
Missouri/southwest Illinois may hit 40 degrees mid morning before
falling and then steadying out in the mid to upper 30s however.

Temperatures Monday night should be the coldest the area has seen
since early March, and by far the coldest so far this young cold
season. Lows in the upper teens and twenties are forecast. The only
reason they are not lower (and near record lows for the date) is due
to northwest winds staying up just enough to prevent more favorable
conditions for radiational cooling.


Gosselin

&&

.LONG TERM...  (Monday through Next Saturday)
Issued at 236 PM CST Sat Nov 8 2025

(Monday - Monday Night)

Arctic air will remain in place on Monday with highs only in the
upper 30s to near the 40 degree mark. These readings would be about
20 degrees below normal for the date. Northwest winds will be
lighter however so it will not feel as cold as Sunday.

Monday night will be another very cold night, though southerly
return flow should increase after midnight. Lows are expected to be
mostly in the mid 20s, though readings should climb late Monday
night heading toward Tuesday morning. Some spotty low 20s are
expected across favored valleys in southeast Missouri where winds
may tend to stay decoupled/lighter longer into the night.


(Tuesday - Next Saturday)

A warmup will begin on Tuesday as low-level warm air advection
continues to strengthen. The initial warmup looks to be muted
however by increasing mid/high level clouds and limited mixing (~875
hPa) Tuesday afternoon. High temperatures have been lowered a couple
of degrees with readings topping out in the low to mid 50s. While
those would be about 15 degrees warmer than Monday, those values
would still be about 5 degrees below normal.

Moderating temperatures along with dry weather as mid/upper level
heights rise and 850-hPa temperatures climb above +10C on the NAEFS
(>95th percentile). Lows are likely to climb into the 40s/50s with
highs cresting the 70 degree mark Friday and next Saturday.
Confidence in the overall pattern is quite high with only subtle
spread on the WPC 500-hPa height clusters. Spread on the NBM for
highs and lows is also seasonably low, with only about a 5-7 degree
spread on days 6-7. Even the cooler 25th percentile for highs/lows
would be 10+ degrees above normal.


Gosselin

&&

.AVIATION...  (For the 06z TAFs through 06z Sunday Night)
Issued at 1044 PM CST Sat Nov 8 2025

Showers are exiting to the east late this evening with a broad
area of MVFR cigs dropping southeast from Iowa into Missouri. IFR
cigs are largely confined to location north and east of KUIN and
may skim the terminal in the first couple of hours of the period.
IFR potential was covered using a TEMPO group with scattered low
ceilings occasionally becoming BKN/OVC. There is higher
confidence that cigs will remain in MVFR categories until drier
air filters in on northwest flow and clouds evacuate through the
day Sunday.

Gusty northwest winds are expected to persist through much of the
period with strong low level jet dynamics passing overhead tonight
through Sunday evening. Expect MVFR conditions to improve to VFR
rather quickly Sunday as much drier air wrap in from the northwest
last morning Sunday into Sunday afternoon.

Maples

&&

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

$$

WFO LSX