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FXUS63 KLSX 302352
AFDLSX

Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
552 PM CST Fri Jan 30 2026

.KEY MESSAGES...

- There is a chance for flurries tonight, mainly before midnight.

- Low Temperatures will be around 0 degrees both Saturday and
  Sunday morning. Wind chill readings between -5 and -15 can be
  expected Saturday morning.

- There is a slight chance for light snow Sunday, mainly along and
  north of I-70. There is another chance for rain or snow Tuesday
  and Tuesday night.



&&

.SHORT TERM...  (Through Late Saturday Night)
Issued at 425 PM CST Fri Jan 30 2026

A strong short wave is digging through the Midwest this afternoon.
This the broad synopti-scale lift associated with this wave is
interacting with just enough moisture to produce clouds and
intermittent light snow across Iowa and Illinois this afternoon. The
clouds and precip will spread south ahead of the base of the trough
trough the rest of the afternoon into the evening.  Short range
guidance is largely dry with just a few CAMs showing some very
spotty and light precipitation.  REFS measurable snowfall
probabilities are mostly in the 0-14% range with a small area over
southeast Missouri around 30% tonight, and even the 90th percentile
snowfall is under an inch.  With all that in mind, till think
"flurries" is the way to go with the forecast tonight rather than
some low chance for measurable snow.

Attention turns to Saturday morning and low wind chill readings.
Another Arctic high is building south from Canada into the Great
Plains and Midwest.  With near zero air temperatures and winds
between 5 to 10 mph, wind chill values will drop to between
-5 and -15 early Saturday morning.  These wind chill temperatures
are marginal for Cold Weather Advisories for our area, and we`ve
very recently been (much) colder.  Will therefore hold off issuing
an advisory at this time but continue to message through social
media and other means.

The surface ridge will continue moving southeast Saturday and
Saturday night, reaching the lower Mississippi Valley by early
Sunday morning.  Current thinking is there will be plenty of
sunshine Saturday which will allow temperatures to rebound into the
low to mid 20s in most locations Saturday afternoon.  Winds stay
light and variable most of the night with with a mostly clear sky at
least through the evening in Missouri and likely for the entire
night in Illinois.  This will provide another night for excellent
radiational cooling.  That and the persistent snow pack will allow
temperatures to drop once again to between 0 and 5 degrees above.

Carney

&&

.LONG TERM...  (Sunday through Next Friday)
Issued at 425 PM CST Fri Jan 30 2026

The next upstream short wave dips into the Midwest on Sunday as the
Arctic high continues moving east.  Return flow on the
west/northwest side of the high will allow temperatures to warm to
near freezing Sunday afternoon for most of the area.  It will also
bring just enough moisture to produce warm advection precipitation
ahead of the trough for parts of the Mississippi Valley.  Both the
GFS and ECMWF produce very light QPF in our area, mainly along and
north of I-70, and the LREF is showing a 55-60 percent probability
of >0.01" of liquid precip.  However probabilities drop off quickly
with each additional hundredth of liquid, and by >0.04" it`s only
about 15 percent.  NBM PoPs have dropped to around 20 percent, but
this may be explained by a persistent dry layer below 5000 feet
depicted in forecast soundings.  At any rate, the column should be
cold enough that any precip that makes it to the surface should be
snow.

The same cannot be said for the next chance for precip which comes
Tuesday.  After a quiet and milder Monday another system moves
through the Mississippi Valley on Tuesday into Tuesday night, which
produces another round of light precip.  Most of the truly cold air
remains bottled up across the Upper Midwest Tuesday, so it looks
like a mix of rain and snow will be possible.  GFS forecast
soundings indicate there could even be a wintry mix of freezing
rain, sleet, and snow. However LREF probabilities of frozen/freezing
precipitation are 10 percent or less.  Even the LREF probability for
measurable precip over all is only 20-40 percent, and mainly over
the eastern Ozarks where temperatures will be warmest.  Therefore I
think the threat for sleet/freezing rain is pretty low at this time,
but should be monitored closely.

The remainder of the forecast through Friday looks dry at this time.
 Temperatures cool off again behind Tuesday`s system as high
pressure builds into the Mid Mississippi Valley, but it will still
be relatively mild by recent standards with highs between 30-35.
Temperatures are milder still Thursday and Friday according to the
GFS in persistent southwest flow.  However the ECMWF pushes another
cold front through the area Friday bringing us cooler temperatures.
EOF patterns from the LREF cluster analysis indicate a great deal of
variance with the short wave powering the front, mainly with its
amplitude.  Additionally, high temperature IQRs are as much as 10
degrees, leading to a low confidence forecast for Friday.


Carney

&&

.AVIATION...  (For the 00z TAFs through 00z Saturday Evening)
Issued at 552 PM CST Fri Jan 30 2026

A southwest to northeast oriented area of high-end MVFR
stratocumulus is slowly drifting to the south across the area and is
already impacting KUIN, KCOU, and KJEF. Within this region, there
are scattered pockets of flurries and light snow being observed with
brief MVFR visibilities possible under the intermittent and somewhat
heavier pockets of snow. Where the heavier snow pockets move over,
reductions to visibility will be brief and likely last less than 30
minutes. This cloud deck and intermittent pockets of light snow is
forecasted to reach the St. Louis metro terminals between 01-02z.
Conditions are expected to improve from north to south later this
evening into early tonight with potential clearing by the early
morning. North surface winds around 10kts will continue overnight
backing to the northwest by tomorrow afternoon.

Peine/Elmore

&&

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

$$

WFO LSX