Area Forecast Discussion

897
FXUS63 KLSX 170432
AFDLSX

Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
1032 PM CST Fri Jan 16 2026

.KEY MESSAGES...

- Snow showers will move through the area this evening. Brief
  bursts of moderate to heavy snow are possible with lowered
  visibility and slick spots. Most locations will see only a
  dusting but a localized stripe of up to 0.5" accumulation cannot
  be ruled out.

- Very cold, well-below average temperatures are expected tonight
  through early Tuesday. The coldest temperatures will be in the
  mornings with single digit F lows and some sub-0 F wind chill
  values mainly along/north of I-70.


&&

.SHORT TERM...  (Through Late Saturday Night)
Issued at 226 PM CST Fri Jan 16 2026

Despite cold frontal passage earlier this morning, temperatures have
warmed into the 40s F across the area leading to a relatively mild
day compared to the preceding and upcoming temperatures. However,
an Arctic cold front is expected to pass through the CWA this
evening, accompanied by snow showers and quickly cooling
temperatures. A broad corridor of scattered showers is already
spreading into the CWA within broad large-scale ascent associated
with a shortwave trough and steep low-level lapse rates. Rain or
perhaps graupel will be the initial precipitation type, but
wetbulbing in heavier showers and overall cooling temperatures will
cause snow to become more predominant. The most intense, numerous
snow showers have been near the Arctic cold front itself with much
strong low-level frontal forcing. Visibilities as low as 1/2 mi or
less and a quick dusting of snow have been observed with these more
intense snow showers now entering northwestern MO. These are
expected to track southeastward through parts of the CWA this
evening, with the potential for sporadic minor impacts to the latter
half of the evening commute from lowered visibilities and slick
spots on roadways. Heavier snow will be very brief (less than 30
mins), but where snow showers repeat or train a localized stripe of
up to 0.5" still cannot be ruled out. Snow showers will decrease in
coverage tonight as forcing and instability weaken, but isolated
snow shower or flurries may linger.

Strong low-level CAA will take place this evening into Saturday,
ushering a very cold, Arctic airmass into the Mid-Mississippi River
Valley, characterized by 850-hPa temperatures nearing the 1st
climatological percentile. Saturday morning will mark the beginning
of a stretch of very cold temperatures as temperatures remain in the
upper teens to 20s F through the day. Additional flurries are also
possible on Saturday across the CWA as another shortwave trough/low
clips the Mid-Mississippi River Valley. Currently, HREF
probabilities of measurable snow are less than 15 percent and higher
to the north of the CWA, but the threat of light accumulating snow
will need to be monitored if the shortwave trough and deeper forcing
and moisture shift further south.

Pfahler

&&

.LONG TERM...  (Sunday through Next Friday)
Issued at 226 PM CST Fri Jan 16 2026

Model guidance continue to come into better agreement on
temperatures Sunday morning through Tuesday morning with the coldest
temperatures expected Sunday morning and then late Sunday night
through Tuesday morning behind another Arctic cold front on Sunday.
Low temperatures are forecast to reach the single digits to mid-
teens F in these periods from both a combination of airmass depth
and favorable radiational cooling (Sunday morning and Tuesday
morning). With these temperatures and even light winds, ensemble
model probabilities of sub-0 F wind chill values are 30 to 60
percent along/north of I-70 Sunday and Tuesday morning and 60 to 90
percent on Monday morning when winds will be stronger. The
probability of values reaching Cold Weather Advisory criteria (

NWS LSX Office Area Forecast Discussion