Area Forecast Discussion

800
FXUS63 KLSX 291016
AFDLSX

Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
416 AM CST Mon Dec 29 2025

.KEY MESSAGES...

- After a cold and blustery day, winds will die down tonight and
temperatures will warm roughly 10 degrees on Tuesday.

- Near to below normal temperatures will persist through the
  weekend, though uncertainty in the temperature forecast is
  higher than normal.


&&

.SHORT TERM...  (Through Late Tuesday Afternoon)
Issued at 213 AM CST Mon Dec 29 2025

Winds continue to gust into the 30s to 40s area wide this morning as
the surface pressure gradient remains tight. The surface pressure
gradient will slacken through the morning as yesterday`s surface low
pushes eastward and a surface high spills into the area. While winds
will remain elevated, gusting into the 30s, through much of the day,
they will decrease in speed through tonight.

Strong cold air advection in the wake of yesterday`s front will
continue today, resulting in high temperatures in the 20s across
most of the area. By Tuesday the surface high will sink south of the
forecast area, and subsequent westerly winds will help to advect
warmer temperatures into the region. The WAA combined with increased
sunshine will result in Tuesday`s highs nearly 10 degrees warmer
than today.

Delia

&&

.LONG TERM...  (Tuesday Night through Sunday)
Issued at 213 AM CST Mon Dec 29 2025

The warming trend will continue Wednesday, finally pushing our
temperatures back to near normal. Meanwhile, a mid-level low will
churn over southeastern Canada Wednesday, with a mid-level ridge
over the Four Corners region, leaving the mid-Mississippi Valley in
northwest flow between the two. During the day, the surface low over
southeast Canada associated with the mid-level low will send a cold
front southward into the upper Mississippi Valley. The dry cold
front will sink into the forecast area overnight into Thursday,
bringing a shot of cooler air to the region. Uncertainty still
exists in if this feature will move through the entire CWA, how cold
it will be, as well as how quickly it moves northward as a warm
front. This results in uncertainty in temperatures from Thursday
through the end of the weekend, roughly 10-15 degrees in the
interquartile spread. Despite this, the 25th percentile of the
interquartile spread for high temperatures during this period is
only about 10 degrees below normal for this time of year, increasing
confidence that this surge of cold air will be less intense than
today`s.

By Friday the mid-level low will lift northward into the Hudson Bay
region, leaving room for a shortwave to move through the southern
stream of the mid-level flow, through the mid to lower Mississippi
Valley. While current ensemble guidance keeps a majority of this
precipitation south of the forecast area and keeps the extended
forecast dry for now, changes in the track of this system could
result in increasing precipitation chances across the southern
forecast area.

Delia

&&

.AVIATION...  (For the 12z TAFs through 12z Tuesday Morning)
Issued at 407 AM CST Mon Dec 29 2025

MVFR stratus will move south into the terminals this morning,
at KUIN the stratus will linger into the afternoon hours before
enough dry air can scatter out the deck. Elsewhere, MVFR ceilings
are expected to linger for the first few hours of the TAF period,
lifting and scattering around 18Z.

Strong, gusty northwesterly winds will continue through the day,
but will diminish in strength overtime as the surface high lifts
out of the area and the surface pressure gradient slackens. By
this evening winds are expected to be gust- free and sustained at
or below 10kts.

Delia

&&

.LSX WATCHES/WARNINGS/ADVISORIES...
MO...Wind Advisory until 6 AM CST early this morning for Audrain MO-
     Boone MO-Callaway MO-Cole MO-Crawford MO-Franklin MO-
     Gasconade MO-Iron MO-Jefferson MO-Knox MO-Lewis MO-Lincoln
     MO-Madison MO-Marion MO-Moniteau MO-Monroe MO-Montgomery MO-
     Osage MO-Pike MO-Ralls MO-Reynolds MO-Saint Charles MO-
     Saint Francois MO-Saint Louis City MO-Saint Louis MO-Sainte
     Genevieve MO-Shelby MO-Warren MO-Washington MO.

IL...Wind Advisory until 6 AM CST early this morning for Adams IL-
     Bond IL-Brown IL-Calhoun IL-Clinton IL-Fayette IL-Greene IL-
     Jersey IL-Macoupin IL-Madison IL-Marion IL-Monroe IL-
     Montgomery IL-Pike IL-Randolph IL-Saint Clair IL-Washington
     IL.

&&

$$

WFO LSX

NWS LSX Office Area Forecast Discussion