287
FXUS63 KLSX 102314
AFDLSX

Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
514 PM CST Mon Nov 10 2025

.KEY MESSAGES...

- Subfreezing temperatures are expected again tonight with lows in
  the mid 20s. The rest of the week will be warmer with highs
  warming into the 70s on Friday and Saturday.

- There is a chance for rain this weekend, mainly Saturday night
  through Sunday.


&&

.SHORT TERM...  (Through Late Tuesday Afternoon)
Issued at 142 PM CST Mon Nov 10 2025

Cold high pressure centered over the southeast Plains will drift
southeast to The Gulf Coast tonight.  Wind across the Mississippi
Valley will turn back to the south as the ridge axis passes to the
east.  This will turn the wind to the south, beginning our warmup
for the week.  The wind will be fairly light and variable as the
ridge axis traverses the area this evening.  The sky should be
relatively clear this evening, and the light wind will allow produce
good radiational cooling conditions allowing temperatures to drop
quickly back below freezing this evening.  However, increasing high
clouds and the increasingly south wind will cause temperatures to
level off in the low to mid 20s early, and either remain steady or
rise slowly toward daybreak.

Warm advection on southwest flow continues Tuesday, however the high
clouds appear to stick around for most of the day.  With that in
mind, temperatures won`t warm quite as much as they otherwise would,
however all temperature guidance points to a much warmer day with
highs up to 20 degrees warmer than today in the mid to upper 50s in
most locations.  LREF, NBM as well as traditional MOS all show these
temperatures, and IQRs are only 2-3 degrees in the ensemble
guidance so confidence is high in these temperatures.  What is less
certain is how high dew point temperatures will rise tomorrow
afternoon.  All short range guidance shows increasing dew point
temperatures tomorrow, with most hitting 25-30 degrees around max-
heating during the afternoon.  THis produces minimum relative
humidity values between 35-40 percent in most locations.  Winds are
forecast to be diminishing slowly in the afternoon as the high
pressure system to our southeast continues to move away and the
pressure gradient slackens. Given these relative humidity values,
diminishing winds, and cloud cover, I believe the elevated fire
danger potential will be marginal on Tuesday afternoon. However, a
decrease in dew point temperature of just 2-3 degrees would
certainly land us squarely in elevated fire danger territory so
conditions will need to be monitored closely.

Carney

&&

.LONG TERM...  (Tuesday Night through Next Monday)
Issued at 142 PM CST Mon Nov 10 2025

The remainder of the week looks relatively uneventful with the Mid
MIssissippi Valley stuck in northwest flow aloft.  A subtle short
wave moves across the Great Lakes Tuesday night, and its surface
reflection turns the wind back to the northwest over Missouri and
Illinois on Wednesday.  However, temperatures are forecast to be in
the mid to upper 30s to start the day, and strong sunshine under a
mostly clear sky will allow temperatures to warm back into the low
to mid 60s Wednesday afternoon.  The warming trend continues Friday
and Saturday with highs topping out in the 70s as a strong upper
level ridge moves from the Great Plains into the Midwest.  The next
chance for rain comes late Saturday into Sunday as another low
pressure system moves across the Midwest and pushes a cold front
through Missouri and Illinois.  There are timing and strength
differences between models with this front, therefore confidence in
the forecast for the weekend into early next week is low.  IQRs rise
from only 2-3 degrees on Friday to more than 10 degrees on Sunday.
Generally speaking, temperatures should be cooler on Sunday and
Monday with highs falling back into the 50s and 60s.  The
deterministic GFS produces a decent round of rain for our area
starting Monday afternoon as the front moves into Missouri and
Illinois, then stalls over the Ozarks Sunday night into Monday. Rain
continues Monday as a wave moves along the front, finally pushing it
through.  The ECMWF has little if any rain for our area through the
period with the front pushing all the way through Alabama by 00Z
Monday.  The NBM generated PoPs of 30-50 percent for Saturday night
through Monday, and this looks reasonable given the
time frame and uncertainties.

Carney

&&

.AVIATION...  (For the 00z TAFs through 00z Tuesday Evening)
Issued at 503 PM CST Mon Nov 10 2025

VFR conditions are expected throughout the 00Z TAF period. Wind
remains the primary concern, particularly during the day tomorrow.
While surface winds will weaken and become southerly overnight,
winds will increase substantially tomorrow morning, veer slightly
to the southwest and peak in the early afternoon, and finally veer
slightly more and weaken in the late afternoon. Meanwhile,
substantial high level cloud cover will also move through the
area, although ceilings will remain well above VFR levels.

Early tomorrow morning, there may be a brief 2 to 4 hour period of
marginal low level wind shear, mainly at COU/JEF, due to
rapidly strengthening winds aloft. Whether or not this actually
materializes will hinge on how quickly surface winds respond to
these increasing winds aloft. If surface winds are slower to
increase, this would lead to more LLWS. Considering that this
window appears brief, our confidence is too low to include LLWS
in the TAF at this time.

BRC

&&

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

$$

WFO LSX