369
FXUS63 KLSX 251729
AFDLSX

Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
1129 AM CST Sun Jan 25 2026

.KEY MESSAGES...

- Additional snow accumulations are expected this morning and
  early afternoon, with the heaviest remaining snow expected
  across southwest Illinois and southeast Missouri. These areas
  will see the most prolonged impacts, but even light additional
  accumulations elsewhere will continue to impact roads across a
  broad area. Snowfall intensities will gradually diminish through
  the day, and largely end prior to sunset.

- Very cold temperatures are expected overnight and Monday
  morning, with below zero actual temperatures expected in a
  majority of the region. Wind chills are also likely to reach 15
  to 20 below in most areas, and even slightly lower some places
  as well. A large portion of the Cold Weather Advisory has been
  upgraded to an Extreme Cold Warning.

- Cold temperatures will maintain a persistent snowpack for the
  remainder of the week, with only some modest improvement Tuesday
  and Wednesday afternoons.


&&

.SHORT TERM...  (Through Late Monday Afternoon)
Issued at 334 AM CST Sun Jan 25 2026

As of 2 AM, a major winter storm is unfolding across our area, with
widespread significant snowfall impacting roadways across the vast
majority of our forecast area. While several more inches of snow are
likely in some areas, we are now just slightly past the overall
peak of this event in terms of average snow intensities, although
moderate to heavy snow is expected to continue for another 2 to 3
hours before snowfall rates begin to diminish more noticeably
after approximately 5 and 6 am. All-in-all, the majority of our
Winter Storm Warning areas will see warning level snow amounts (5+
inches) and some areas in southeast Missouri and southwest
Illinois are likely to reach and even slightly exceed 1 foot by
the time accumulating snow ends sometime in the afternoon.

While direct snow measurements are difficult to obtain at this late
hour, radar trends, ASOS observations, and area webcams continue to
suggest that widespread moderate to heavy snow continues to fall
across a broad footprint, with the most significant rates (very
likely in the 1 to 2 inch per hour range) occurring along and south
of the I-44 corridor, with more modest but still impactful
accumulating rates (up to 1 inch per hour) farther north across the
remainder of the Winter Storm Warning footprint. The St. Louis metro
are has already seen at least 4 to 6 inches of snow as of this
writing, and is currently seeing rates in that more "moderate"
category. Still, thanks to very efficient snow to liquid ratios
(roughly 15 to 1) these snow rates are still plenty high enough in
the metro area to produce another 2 to 3 inches of fluffy snow
before it finally ends later in the day, likely by early to mid
afternoon. Even higher additional totals are likely south of I-44,
with as much as 3 to 5 inches of additional snow on the way. The
higher numbers in that range are most likely to occur across
southwest Illinois, given that those areas are farther east and not
quite as far along in this event as Missouri. We did see some
evidence of sleet mixing in with snow in some of these areas earlier
in the night as well, but this has largely diminished and it does
not appear to have impacted totals much based on nearby observations.

Farther northwest, roughly across our Winter Weather Advisory
footprint and perhaps a few additional counties in central Missouri,
snowfall rates are generally much lower as evidenced by higher
visibilities in ASOS observations and radar trends. However,
additional light accumulations are possible even here over the next
few hours as well. An additional dusting to 2 inches is possible in
these areas, with the lowest remaining amounts across far northeast
Missouri where very little snow is currently falling.

As the sun rises, snowfall rates are expected to steadily diminish
through the morning and early afternoon. However, light snow
accumulations are likely to continue until at least noon in many
areas, and potentially into the mid/late afternoon (2 to 4 PM) in
southwest/south-central Illinois as the last remnants of the
deformation zone sweeps through the area. Meanwhile, the continued
cold will also keep snow on the roads until it is cleared,
prolonging travel impacts well after new snow stops falling.

Given all of the above, no changes were made to ongoing Winter Storm
Warning and Winter Weather Advisory. It is possible that some
portion of these areas may end up being cancelled a few hours early,
but given the potential for light accumulations to persist into the
afternoon, and the potential for lingering impacts due to snow
lingering on road surfaces, we`ve opted to hold off on that for now.

By Sunday evening, attention then turns to temperatures and wind
chills, as things are shaping up for a very cold night across the
entire area. The combination of the already present cold airmass, a
fresh dry snowpack, clearing skies, and weakening winds in many
areas is a recipe for plummeting temperatures. Overnight lows are
very likely to drop below zero in most areas, likely even in the
major metro areas, and may reach into the double-digits below zero
in the most wind-sheltered valleys. While winds are expected to
gradually weaken, even the remaining 5 to 10 mph wind will be enough
to drive wind chills to at least 15 below across the majority of the
forecast area, and likely near or even less than 20 below. The
coldest wind chills will be most likely in southwest Illinois where
slightly higher breezes are forecast. In response, we have upgraded
the portion of our area to an Extreme Cold Warning, encompassing all
of southeast Missouri and southwest Illinois, along with a small
portion of central Missouri and the St. Louis metro area. This
represents the portion of our area with a -20 degree wind chill
threshold for an Extreme Cold Warning, while the remainder of our
area will remain within an Advisory (for now) due to having a
slightly higher criteria of -25 degrees.

BRC

&&

.LONG TERM...  (Monday Night through Saturday)
Issued at 334 AM CST Sun Jan 25 2026

From Monday onward, the primary focus remains on temperatures, as an
extended stretch of cold conditions is likely to follow our heavy
snow event. This will maintain a snowpack through the end of the
week in most areas through the end of the week and into the weekend,
especially in areas that see the highest totals.

Driving this trend will be a persistent northwest flow pattern,
featuring a large stationary trough across the Great Lakes and
eastern CONUS that will send several smaller shortwaves through our
area over the course of the week. Under such a pattern, well below
average temperatures will be continually reinforced, and while we
will see a modest improvement from the most bitter cold Monday
morning, we will remain well below average through the end of the
week. In fact, a large portion of the area is likely to remain below
freezing through the end of the week as well, with only a few parts
of the Ozarks possibly reaching very near the freezing mark Tuesday
and Wednesday afternoons. This may help to melt some snow on
pavement during the day, but morning lows consistently in the single
digits and teens throughout the week will promote nightly re-
freezing, and will significantly limit snowpack reduction.

Otherwise, precipitation chances remain low throughout the week,
aside from some minor snow chances (20% or less) as shortwaves
move through the area Wednesday and again Friday. More details
will be known about these system in the coming days, but the
potential for impactful accumulations with either of them
currently does not appear to be high.

BRC

&&

.AVIATION...  (For the 18z TAFs through 18z Monday Afternoon)
Issued at 1122 AM CST Sun Jan 25 2026

Impacts are decreasing across the region as the winter storm
system departs eastward. The last gasp of snow will continue
impacting the St. Louis metro terminals through early this
afternoon. Visibilities may drop lower than currently forecast,
but the decreasing intensity in snowfall rates is expected to have
an upward trend in visibilities overall. The back edge of the
system`s cloud deck is approaching from the west, and is
currently over KCOU and KJEF. Observations have been showing
isolated, brief drops in ceilings to MVFR with this clearing line.
The brevity of these drops and their isolated nature has
confidence too low in them to put in the TAFs right now, and they
will continue to be monitored for more persistent impacts. Once
clouds and snow clear the terminals, VFR flight conditions are
expected through the remainder of the forecast period.

Elmore

&&

.LSX WATCHES/WARNINGS/ADVISORIES...
MO...Winter Storm Warning until 6 PM CST this evening for Audrain MO-
     Boone MO-Callaway MO-Cole MO-Crawford MO-Franklin MO-
     Gasconade MO-Iron MO-Jefferson MO-Lincoln MO-Madison MO-
     Moniteau MO-Montgomery MO-Osage MO-Pike MO-Ralls MO-
     Reynolds MO-Saint Charles MO-Saint Francois MO-Saint Louis
     City MO-Saint Louis MO-Sainte Genevieve MO-Warren MO-
     Washington MO.

     Extreme Cold Warning from midnight tonight to noon CST Monday
     for Callaway MO-Cole MO-Crawford MO-Franklin MO-Gasconade
     MO-Iron MO-Jefferson MO-Lincoln MO-Madison MO-Moniteau MO-
     Montgomery MO-Osage MO-Reynolds MO-Saint Charles MO-Saint
     Francois MO-Saint Louis City MO-Saint Louis MO-Sainte
     Genevieve MO-Warren MO-Washington MO.

     Cold Weather Advisory from midnight tonight to noon CST Monday
     for Audrain MO-Boone MO-Knox MO-Lewis MO-Marion MO-Monroe
     MO-Pike MO-Ralls MO-Shelby MO.

IL...Winter Storm Warning until 6 PM CST this evening for Bond IL-
     Calhoun IL-Clinton IL-Fayette IL-Greene IL-Jersey IL-
     Macoupin IL-Madison IL-Marion IL-Monroe IL-Montgomery IL-
     Pike IL-Randolph IL-Saint Clair IL-Washington IL.

     Extreme Cold Warning from midnight tonight to noon CST Monday
     for Bond IL-Calhoun IL-Clinton IL-Fayette IL-Greene IL-
     Jersey IL-Macoupin IL-Madison IL-Marion IL-Monroe IL-
     Montgomery IL-Randolph IL-Saint Clair IL-Washington IL.

     Cold Weather Advisory from midnight tonight to noon CST Monday
     for Adams IL-Brown IL-Pike IL.

&&

$$

WFO LSX