698
FXUS63 KLSX 022015
AFDLSX

Area Forecast Discussion
National Weather Service Saint Louis MO
215 PM CST Tue Dec 2 2025

.KEY MESSAGES...

- Up to a dusting of light snow is possible tomorrow evening and
  overnight, particularly along and north of I-70.

- Well below average temperatures are expected tomorrow night
  through Friday morning, with a chance to reach or set daily
  record minimums. While this will improve Friday onward,
  temperatures will remain below average.

- While forecast confidence is low, another round of light wintry
  precipitation is possible late in the weekend.

&&

.SHORT TERM...  (Through Late Wednesday Night)
Issued at 211 PM CST Tue Dec 2 2025

Chilly, but relatively quiet weather conditions are in place this
afternoon after successive early-season snow events impacted the
region over the past several days. Satellite imagery reveals an
expansive snowpack roughly along and north of I-70, although this is
more difficult to see underneath a blanket of stubborn stratus in
many areas. These low clouds have persisted into the afternoon
across large portions of eastern Missouri and most of Illinois, and
between that and the lingering snowpack, temperatures have remained
below freezing in most areas. While we will likely break the
freezing mark in parts of central and southeast Missouri by mid
afternoon, this is still well below seasonal averages for early
December (upper 40s).

Overnight, these low clouds will gradually diminish, but will be
replaced by a steadily increasing stream of high clouds ahead of an
approaching shortwave and cold front. In any case, chilly
temperatures are expected, with lows ranging from the mid 20s in
central/southeast Missouri on the upper end, to the mid teens in
south-central Illinois on the low end.

Attention then turns to the arrival of another cold front late in
the day Wednesday, which will be discussed in more detail in the
long-term section below.

BRC

&&

.LONG TERM...  (Thursday through Next Tuesday)
Issued at 211 PM CST Tue Dec 2 2025

While much of the day Wednesday will be dry and uneventful, this
will be short lived as a cold front will usher in an unseasonably
cold airmass this evening and overnight. This cold front will be
driven south by a digging trough across the Great Lakes, and while
we will be somewhat far removed from the trough itself, the
expansive continental polar airmass behind it will have more than
enough momentum to spread frigid temperatures into our area
overnight.

Before the core of the cold air spills fully into the area though,
we will need to keep an eye on the potential for some light snow
along and behind the cold front this evening and overnight, due to
some modest low and mid-level frontogenesis. Moisture is somewhat
lacking and the majority of the lift is not well-aligned with the
most favorable dendritic growth zone, which will severely limit the
upper end potential of any snow that falls. However, there are some
hints that a few areas could see as much as a light dusting, and
considering that this would largely occur at night, we can`t rule
out a brief coating on roads in a few spots...especially north of I-
70. Still, even this light dusting represents the 90th percentile of
ensemble members, so we don`t expect this to be a significant issue.
We`ll also need to keep an eye on an even lower probability (10%) of
a very brief period of freezing drizzle, although we would need to
thread a precariously small needle for this to be realized and we do
not expect impacts from this.

The bigger story at the moment continues to be the upcoming cold,
spanning roughly a 36 hour period from overnight tomorrow through
Friday morning. High confidence exists that low temperatures both
tomorrow morning and Friday morning will drop into the teens to
single digits area-wide, and perhaps even make a run at 0 degrees in
the coldest parts of northeast Missouri and central Illinois. In
between, afternoon temperatures Thursday may not climb out of the
teens in many areas, although there will likely be a sharp gradient
in temperatures across the area Thursday afternoon with parts of the
Ozarks climbing closer to the freezing mark. In any case, daily
record low temperatures will be within striking distance at all of
our local climate sites Thursday and Friday mornings, not to mention
record low maximums Thursday afternoon. Latest operational NBM
forecast temperatures have increased a couple of degrees from the
previous forecast, but not enough to eliminate the possibility of
reaching or breaking a couple of those records.

Friday through early next week, the synoptic scale pattern is
expected to remain somewhat stagnant, with a low-amplitude and low-
latitude longwave tough settling in across the eastern U.S. This
will keep us within mostly northwest flow aloft, and will help to
lock in below-average temperatures through the end of the forecast
period. We will see a rebound from Thursday/Friday`s frigid
temperatures, but current ensemble forecasts project that we will
likely remain at least 5 to 15 degrees below average through early
next week.

While the medium-range pattern does not suggest a high probability
of heavy precipitation, we continue to watch a deepening shortwave
that will likely move through the region over the weekend. There
continues to be considerable track/timing differences with this
feature, which is likely washing out some of the forecast amounts in
the current operational forecast. However, we do see 75th-90th
percentile QPF amounts reaching the .10-.20 inch range, the vast
majority of which would fall as some sort of frozen precipitation
type and would be enough to cause minor impacts to travel. As such,
we will need to monitor this system over the next few days as model
agreement improves.

BRC

&&

.AVIATION...  (For the 18z TAFs through 18z Wednesday Afternoon)
Issued at 1114 AM CST Tue Dec 2 2025

IFR/MVFR stratus continues to impact many local terminals as we
approach the start of the period, although there has been gradual
improvement at central MO terminals (SUS/JEF). These terminals
should clear out very shortly, followed by UIN and St. Louis area
terminals (STL/SUS/CPS) later in the afternoon. VFR conditions
are expected the remainder of the night and into tomorrow morning.

Near the end of the period a cold front will approach the area,
and may reach UIN near or just prior to 18Z tomorrow, and the
remaining terminals between roughly 20-00Z. Most of the impacts
from this will be felt just beyond this forecast period, but low
clouds and some light snow will be possible.

BRC

&&

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

$$

WFO LSX