Area Forecast Discussion

401
FXUS63 KLSX 311008
AFDLSX

Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
408 AM CST Sat Jan 31 2026

.KEY MESSAGES...

- Wind chills this morning will drop as low at -5F to -15F before
temperatures warm to around 20F.

-There is a 20-30% chance for light snow north of I-70 Sunday
afternoon and evening. Accumulations up to a quarter inch are
possible.

-The next chance for rain/snow will be Tuesday into Wednesday.



&&

.SHORT TERM...  (Through Late Sunday Afternoon)
Issued at 258 AM CST Sat Jan 31 2026

Overnight flurries are rapidly moving south out of the forecast
area early this morning as the mid-level trough axis producing
them does likewise. While scattered light accumulations (less than
0.1") have been reported across portions of east-central
Missouri, impacts are not expected.

Lingering clouds over southeast Missouri and southern Illinois this
morning are keeping temperatures relatively elevated, in the mid
teens compared to the remainder of the CWA, where temperatures have
fallen below 10F despite elevated winds. While breaks in the clouds
will help temperatures locally fall an additional few degrees,
overnight lows are expected to be warmer than previously forecast.
The result will be slightly warmer wind chills in the negative
single digits, which will keep the area free from Advisory level
wind chills. While wind chills will still drop to roughly -5 to
-15 degrees, the coldest wind chills will be limited in both space
and duration. Thus we have not issued any official cold weather
products this morning.

Conditions today will be similar to yesterday under the influence of
the surface high to the west and in the wake of cold air
advection this morning. Despite a mostly clear sky, temperatures
will peak around 20 degrees area wide.

After a cold start Sunday morning with -5F to 5F wind chills, the
warm up will kick off as low-level warm air advection starts up
and surface winds become southwesterly on the northwest side of
the exiting surface high. Temperatures are expected to warm into
the 30s. At the same time, another mid-level shortwave will slide
down the northwest mid-level flow and bring a 20-30% chance for
snow to portions of the forecast area north of I-70 Sunday
afternoon and evening. There is some uncertainty in how much
moisture will be available across this area, and so how far south
the snow will reach. Where snow does fall it will be light, a
quarter of an inch accumulation or less. The HREF LPMM total
snowfall indicates less than an inch of accumulation even across
our northern border, increasing confidence in low impacts.

Delia

&&

.LONG TERM...  (Sunday Night through Friday)
Issued at 258 AM CST Sat Jan 31 2026

Heading into the work week there is at least one other chance for
precipitation. A mid-level shortwave will increase in strength
while it moves into the central CONUS along the eastern side of a
mid-level ridge Tuesday into Wednesday. The surface reflection
will form across Texas and move east-northeast into the mid-
Mississippi Valley. Ahead of this system, warm air advection along
southerly flow will facilitate moisture return Monday into
Tuesday. Guidance has waffled on how far north to bring this
system, though current deterministic and ensemble guidance keep a
majority of the precipitation associated with this system across
southern Missouri and Illinois. The warm air advection associated
with this system is expected to warm near surface temperatures as
well as temperatures aloft, resulting in a mix of rain and snow.
Rain is most likely across southeast Missouri and southern
Illinois, but the track of the system will impact where the
transition zone into snow occurs as well as how much precipitation
falls. Some sources are hinting at the potential for freezing
rain or sleet with this system, though the NBM only has a 12%
chance of this occurring in the transition zone between rain and
snow. Confidence is low in this occurring.

The next system is expected to occur Friday into the weekend
associated with the axis of a strong mid-level trough that slides
into southeastern Canada by the end of the work week. The
resulting surface low is currently forecast to remain near the
Great Lakes region. With limited moisture across the region, the
precipitation shield is expected to be limited. The current
position of this system does not favor precipitation across our
forecast area, however changes in the track and intensity of this
system could bring additional precipitation chances to the
forecast area.

Temperatures will increase starting Sunday and continuing into the
first half of the work week with highs in the 30s. A brief and
relatively mild cool down is expected Wednesday behind the midweek
system, though the interquartile spread for high temperatures
Wednesday still keeps highs reaching into the upper 20s to mid 30s
areawide. Towards the end of the work week uncertainty with the mid
and low-level patterns results in uncertainty with high
temperatures, and the interquartile spread increases to around 10
degrees.

Delia

&&

.AVIATION...  (For the 12z TAFs through 12z Sunday Morning)
Issued at 407 AM CST Sat Jan 31 2026

Dry and VFR flight conditions will continue through the TAF
period. Northerly winds will dominate today, remaining elevated
above 10 kts. By evening the surface high currently to the west
will weaken and expand across the region, causing winds to go
light and variable overnight.

Delia

&&

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

$$

WFO LSX

NWS LSX Office Area Forecast Discussion