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FXUS63 KLSX 281034
AFDLSX

Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
434 AM CST Wed Jan 28 2026

.KEY MESSAGES...

- After today`s relative warmth, brutal cold will return to end
  the week. Dangerous wind chills are possible Friday, Saturday,
  and Sunday mornings.

- Very light snow is possible (<20% chance) Thursday night for
  much of the area. If snow does fall, isolated slick spots may
  occur on untreated roads.

- Our next best chance of accumulating snow will arrive Sunday
  into Monday. Though confidence is high in this timeframe, there
  are many uncertainties concerning any other details at this
  point.


&&

.SHORT TERM...  (Through Late Thursday Afternoon)
Issued at 353 AM CST Wed Jan 28 2026

With the help of sunshine and warm air advection, today`s highs will
be boosted into the 20s and 30s, 25-30 degrees warmer than this
morning`s lows. Portions of southeast Missouri may even see
temperatures rise above freezing today. The "warmth" will be short-
lived, however, as a series of mid-level shortwaves ushers in rounds
of cold air. The first shortwave arrives on Thursday, and for those
closest to the airmass`s core, its influence will be immediately
apparent. Highs north of I-70/I-64 are forecast to be 5-10 degrees
cooler than this afternoon. More notably, this system may bring
flurries or light snow to the CWA Thursday afternoon into evening.
High-res guidance is keying in on 2 potential areas during this
timeframe: 1 north of I-70, and 1 in the Ozarks. However, a lack of
moisture will limit how much the atmosphere will actually be able to
squeeze out regardless of location. HREF probabilities of both
0.01" of QPF and 0.1" of snow over 24 hours ending Thursday
evening peak at 50 - 60%. This isn`t taking into consideration the
time it will take the low-levels to saturate. In short, models
are coming to a consensus in light snow falling Thursday, and
confidence is very high (>80%) that this will be light. With how
cold it`s been, any snow that does fall will stick to the ground
and to untreated roads. Even a dusting may be enough to cause
isolated slick spots.Jaja

&&

.LONG TERM...  (Thursday Night through Tuesday)
Issued at 353 AM CST Wed Jan 28 2026

The next wave will be much more potent. Guidance is centering in on
it passing late Friday into early Saturday. As it passes, the
feature will escort a blast of brutally cold Arctic air into the
region. Global models only keep intensifying the strength of the
airmass, now showing a 1045 mb surface high carrying 850 mb
temperatures of -20C into the Mid-Mississippi Valley. These values
register in the 99.5th and 0.5th percentiles of climatology,
respectively. Unsurprisingly, the Extreme Forecast Index for this
weekend reflects this, showing high confidence for a very unusual
to extreme event regarding both high and low temperatures. Though
exact air temperatures and wind chills are still uncertain, we`ve
got enough evidence to state the obvious. It`s going to be
dangerously cold again. The coldest morning is currently Saturday
morning with wind chills of -10 to -15 degrees areawide. These
values will wobble as models adjust the placement and intensity of
the surface high, but as for right now these are pretty safe
values to use for preparation of any kind.

The chance of snow increases again Sunday into Monday with the
passage of a couple more shortwaves. The LREF shows a 50% chance of
measurable precipitation in the northern CWA during this timeframe.
I think it`s important to add that this percentage comes from 2 very
deterministic forecasts from the ECMWF and GEFS, with the first
pushing out a 90% chance of snow and the second only reaching 10%.
So although the LREF`s 50% probability of measurable precipitation
would translate to a "high chance" in our terms, what it actually
reflects is an average of a few very different solutions that are
all possible at this range.

Jaja

&&

.AVIATION...  (For the 12z TAFs through 12z Thursday Morning)
Issued at 433 AM CST Wed Jan 28 2026

Dry and VFR conditions will prevail through the period. Light
winds will pick up from the west today before becoming light and
variable again tonight.

Jaja

&&

.LSX WATCHES/WARNINGS/ADVISORIES...
MO...None.
IL...Cold Weather Advisory until 9 AM CST this morning for Bond IL-
     Clinton IL-Fayette IL-Macoupin IL-Marion IL-Montgomery IL.

&&

$$

WFO LSX