Area Forecast Discussion

525
FXUS63 KLSX 211105
AFDLSX

Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
505 AM CST Wed Jan 21 2026

.KEY MESSAGES...

- Confidence remains high in bitter cold over the area beginning
  Thursday night and continuing through Sunday.

- The chance (50-70%) for accumulating snow is increasing from
  late Friday night into Saturday night, particularly over parts
  of southeast Missouri where a Winter Storm Watch has been
  issued.


&&

.SHORT TERM...  (Through Late Thursday Afternoon)
Issued at 331 AM CST Wed Jan 21 2026

Latest regional radar is showing a stream of precipitation
developing across southern Missouri that is moving northeast
toward the far southern CWA. The latest RAP soundings are dry over
these counties, so any precipitation will likely be very light,
so will maintain just a 20 PoP through 13Z for wintry mix.
Thereafter the precipitation will move off to the east in response
to the upper trough currently over the middle Missouri Valley
moving into the Ohio Valley by later this morning. A cold front
will move across the area this morning, but a lack of strong push
of cold air behind it and plenty of sun today will help push highs
back into the 40s today. A second, stronger cold front will move
across the area this evening with winds gusting into the 25 to 30
mph range this afternoon and evening across northeast Missouri and
west central Illinois. Lows tonight will fall into the teens and
lower 20s.

Britt

&&

.LONG TERM...  (Thursday Night through Tuesday)
Issued at 331 AM CST Wed Jan 21 2026

Model guidance remains in overall good agreement that we remain dry
through Friday as a large surface high drops out of central Canada
into the Midwest and Great Lakes.  This high will supply very cold
and dry air to the region with wind chills dropping below -10 over
the northern half of the CWA on Friday morning and across much of
the CWA on Saturday morning.  In addition, highs look like they will
only be in the single digits and teens on Saturday, so we will need
to monitor for Cold Weather headlines in future updates.

Have gone ahead and issued a Winter Storm Watch for Reynolds, Iron,
and Madison counties from late Friday through Saturday night with
the potential for 3 to 6" of snowfall. Both deterministic models
and ensembles have shown a slight shift northward with the system
including QPF which has resulted in an increase in the forecast
snowfall totals in the NBM, particularly over the southern third
of the CWA. Snowfall is be pushed upward by how cold the airmass
is with forecast 13:1 to 18:1 SLRs this weekend. Even with this
said, there remains some uncertainty in the forecast as there
remains some spread in the models as the system is still three
days out and the dry northeasterly flow will likely set up a
sharp north to south accumulation gradient as it has in past
storms. The LREF is showing that the 25th/75th percentile is
showing 3" difference along and south of I-70 with snowfall totals
and even greater in the 10th/90th. However, with any accumulating
snowfall in these cold of temperatures will have the potential to
cause travel impacts.

Britt

&&

.AVIATION...  (For the 12z TAFs through 12z Thursday Morning)
Issued at 456 AM CST Wed Jan 21 2026

Dry and VFR conditions are expected through the period. West to
southwest winds with gust up to 20 knots at times today before
turning out of the the northwest behind a cold front tonight with
gusts up to around 25 knots.

Britt

&&

.LSX WATCHES/WARNINGS/ADVISORIES...
MO...Winter Storm Watch from late Friday night through late Saturday
     night for Iron MO-Madison MO-Reynolds MO.

IL...None.
&&

$$

WFO LSX

NWS LSX Office Area Forecast Discussion