592
FXUS63 KLSX 011054
AFDLSX

Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
454 AM CST Sun Feb 1 2026

.KEY MESSAGES...

-There is a 20-30% chance for light snow along and east of the
Mississippi River today with a dusting up to localized quarter inch
of accumulations. Roads may become slippery.

-The chances of precipitation are decreasing for the mid week period.

-Temperatures will go through a few warm up-cool down cycles, though
generally stay warmer than last week.


&&

.SHORT TERM...  (Through Late Monday Afternoon)
Issued at 223 AM CST Sun Feb 1 2026

While today will dawn cold with morning temperatures in the single
digits to negative single digits in some sheltered locations, a warm
up is on the way. Warm air advection will kick off today along the
backside of a small low-level ridge, helping temperatures to ease
into the upper 20s to low 30s area wide. Temperatures will be
warmest west of the Mississippi River, closest to the warmer airmass
to our west. In the wake of the progressive shortwave ridge, a
shortwave trough will immediately follow today. This will combine
with a north-south oriented front to produce light snow mainly along
and east of the Mississippi River late this morning and into the
evening hours.

QPF has trended upward in the last 24 hours from areas of 0.01-0.02"
across small portions of west-central Illinois, to now showing
widespread 0.01-0.02" along and east of the Mississippi River with
pockets of 0.03". The nature of this snow is expected to be more
banded and irregular, given the frontogenesis at play. The result
will be a widespread dusting with snow accumulations 0.1-0.25" in
localized areas. Slippery roadways, particularly those that do not
still have lingering treatment from last week`s system, are expected.

Warm air advection will continue into Monday, increasing
temperatures nearly 10 degrees from today. Portions of central and
southeast Missouri are projected to reach their maximum temperatures
in the 40s for the first time since early January.

Delia

&&

.LONG TERM...  (Monday Night through Saturday)
Issued at 223 AM CST Sun Feb 1 2026

By Tuesday a mid-level trough will dig into the central CONUS and
during the day a shortwave within the southern portion of the trough
will move into the lower Mississippi Valley. Ensemble guidance
continues to move the resulting surface low largely to the south of
our forecast area through the day Tuesday. Ahead of this system`s
approach a cooler airmass will push into the region with the
approach of the mid-level trough, dropping temperatures back to the
30s for most of the forecast area. The incoming airmass will shift
winds to the north, resulting in limited moisture return ahead of
the surface low. In fact, deterministic and ensemble guidance has
been trending this system drier while it`s within arms` reach of the
LSX forecast area, only ramping up the system`s moisture as it moves
into the Ohio River Valley. All of this results in a continuing
trend of a drier forecast with currently only a 20% chance for
precipitation across southeast Missouri and southern Illinois.

The passage of this system will allow Tuesday`s cold air mass to
ooze southward, and the core of the cold air is expected to move
across the forecast area during the afternoon on Wednesday. This
will result in another cool day with temperatures in the upper 20s
to 30s areawide. Thursday will start another brief warm up that will
continue through Friday as low-level warm air advection increases
from west to east ahead of the next system.

Another mid-level trough axis will bring a surface low through the
Great Lakes region Friday into the weekend. While the surface low is
still forecast to remain to our northeast, ensemble guidance has
been inching this system increasingly closer to the forecast area.
The current forecast is largely dry, but the impact from this system
will be felt in the passage of another cold front. How strong the
push of cold air behind this front will be remains uncertain and
tied in part to the uncertain positioning of the system. The
subsequent 15 degree interquartile temperature spread for the
weekend has temperatures ranging from the 30s to the upper 40s and
low 50s.

Delia

&&

.AVIATION...  (For the 12z TAFs through 12z Monday Morning)
Issued at 435 AM CST Sun Feb 1 2026

Light snow with trace to 0.25" accumulations will move into UIN
between 16-21Z and the St. Louis metro airports between 21-01Z.
MVFR visibilities will be possible with the snow. There will also
be a period of MVFR ceilings between 21-03Z at UIN. Otherwise VFR
flight conditions are expected. Winds are expected to be out of
the south at 5 to 10 knots before becoming light and variable
toward the end of the period.

Britt

&&

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

$$

WFO LSX