519
FXUS63 KLSX 072023
AFDLSX

Area Forecast Discussion
National Weather Service Saint Louis MO
223 PM CST Fri Nov 7 2025

.KEY MESSAGES...

- One last mild day is in store for most Saturday before a blast
  of arctic air brings well-below normal temperatures Sunday -
  Tuesday morning.


&&

.SHORT TERM...  (Through Late Saturday Afternoon)
Issued at 223 PM CST Fri Nov 7 2025

A weak surface ridge will move across the mid-Mississippi Valley
tonight ahead of a hybrid clipper system moving into the central
Plains. Mid/high level clouds will be on the increase from west to
east late tonight, inhibiting radiational cooling across parts of
central Missouri. Low temperatures will only drop back into the
low to mid 40s, with upper 30s more common further east where it
will stay clear longer.

The surface low associated with the hybrid clipper is forecast to
track west-east just north of the I-70 corridor in
Missouri/Illinois. Like a typical clipper, basically all of the
precipitation should be north of the track of the low where stronger
low/mid level frontogenesis and upper-level forcing for ascent
resides ahead of the approaching shortwave. This means that parts of
northeast Missouri and west-central Illinois have the best PoPs (60-
90 percent) are located. Further south, there will be a sharp
gradient with very little chance of light rain south of I-70. There
will also be a sharp temperature gradient from north to south,
perhaps as much as 25 degrees Saturday afternoon. Plenty of clouds
and light rain north of the surface low track may struggle to hit 50
degrees. Meanwhile, parts of southeast Missouri should see plenty of
sunshine with increasing low-level warm air advection. Highs in the
70s are expected in these locations. Model guidance really struggles
with capturing temperature gradients with clippers, and is often too
warm north of the track and conversely too cool to the south. Did
cool highs a few degrees in our far north and bump them up a couple
in our south to try my best to capture this gradient.


Gosselin

&&

.LONG TERM...  (Saturday Night through Next Friday)
Issued at 223 PM CST Fri Nov 7 2025

(Saturday Night - Monday Night)

Behind this clipper, a burst of arctic air will infiltrate the mid-
Mississippi Valley. The air mass is very strong for early/mid
November, with 850-hPa temperatures dropping below -10C over much of
the area. These values are about 15C below normal and just above the
1st percentile for the date on the latest NAEFS. The surface
anticyclone is also very strong late Sunday (1034+ hPa; >99th
percentile) across the central Plains. Temperatures are forecast to
drop to near or below freezing across the area. For Sunday, strong
low-level cold air advection and stratocumulus suggest highs will
not climb out of the 30s for most locations. Those readings would be
near 20 degrees below normal. Given deep, cyclonic flow aloft and a
midlevel disturbance moving across the region, some flurries may
also be around from late Saturday night though Sunday. Flurries may
linger over in Illinois Sunday evening as a secondary midlevel
shortwave dives southward.

Monday morning will see the coldest lows since early March. Lows in
the upper teens to mid 20s are forecast. Northwest winds staying up
well east of the surface high are the only thing keeping
temperatures from being several degrees colder and flirting with
record lows for the date (mid to upper teens).

Monday afternoon should be slightly warmer than Sunday as the core
of the anomalously cold air mass begins to shift eastward. Highs in
the low 40s are forecast across the entire area.

The surface ridge moves quickly across the bi-state area Monday
night, with increasing southerly return flow from west to east
overnight. This will keep temperatures from cooling too much. In
fact, temperatures west of the Mississippi are likely to start
rising after midnight. Before they do though, lows in the mid 20s
are expected with low 20s further east into south-central Illinois
where southerly winds are not expected to increase until after 0900
UTC Tuesday.


(Tuesday - Next Friday)

There is strong confidence in a warming trend beginning on Tuesday,
but how much and how quickly remains a question mark. The ECMWF/EPS
is still slightly slower to move out the deep mid/upper level closed
low off the eastern seaboard and therefore is cooler for Tuesday`s
highs. The spread between the 25th/75th percentiles of the NBM has
narrowed slightly compared to yesterday, but is still in the 5-8
degree range.

A re-emergence of a similar pattern to what we have been in the past
several days looks likely mid/late next week. Multiple weak Pacific
"cold" fronts may move across the area, but there is very little/if
any cool down behind these frontal boundaries. There is high
confidence in dry weather conditions along with a return to mild
conditions (highs in 60s, lows in 30s/40s).


Gosselin

&&

.AVIATION...  (For the 18z TAFs through 18z Saturday Afternoon)
Issued at 1059 AM CST Fri Nov 7 2025

West/northwest winds around 10 knots are expected through the
afternoon. A few gusts to near 20 knots are expected at KUIN.
Winds will subside this evening. A clear sky tonight will
gradually give way to increasing mid/high level clouds late
tonight into Saturday morning, but VFR conditions should prevail.
Some light rain may move into northeast Missouri late Saturday
morning, but the better rain chances hold off at KUIN until the
afternoon.

Gosselin

&&

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

$$

WFO LSX