758
FXUS63 KLSX 010505
AFDLSX

Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
1105 PM CST Wed Dec 31 2025

.KEY MESSAGES...

- A cold front will move through the area tonight. Scattered
  sprinkles or flurries will be possible, mainly across Northeast
  Missouri and west central Illinois.

- Temperatures will remain near normal through the weekend. Warmer
  temperatures are expected next week. However, exactly how much
  warmer remains uncertain.


&&

.SHORT TERM...  (Through Late Thursday Afternoon)
Issued at 201 PM CST Wed Dec 31 2025

The Mississippi Valley remains in northwest flow aloft with a mid-
upper level long wave trough over the eastern U.S. and a ridge over
the west.  A short wave is moving into the Great Lakes Region this
afternoon, and will continue to rotate southeast around a stacked
low over the Hudson Bay.  The surface reflection of the wave is
dragging a cold front through the Upper Midwest at this time, and
short range guidance shows the front moving into northern Missouri
and central Illinois between 04-06Z.  The front continues into
southern Missouri and Kentucky on New Year`s Day where it is
expected to stall and remain nearly stationary through Thursday
night.  Short range guidance is hinting there could be some
flurries/sprinkles forced by modest frontogenesis behind the front
tonight.  However, limited moisture makes any accumulating precip
extremely unlikely (<10%). Temperatures behind the front on New
Year`s Day look about 5-8 degrees cooler than today except in the
vicinity of the front where the cooler air does not reach.


Carney

&&

.LONG TERM...  (Thursday Night through Next Wednesday)
Issued at 201 PM CST Wed Dec 31 2025

Another short wave moves into the Great Plains on Thursday night
which produces a surface low that moves from southern Oklahoma
across the Deep South Friday and Saturday.  Deterministic guidance
continues to keep our southeast Missouri counties dry on Friday as
the low moves along the Louisiana/Arkansas border.  However the
latest NBM has introduced some ~20% PoPs, mainly to Reynolds, Iron,
Madison, St. Francois, and Ste. Genevieve counties Friday afternoon
and evening.  15-20 percent of the LREF members are also producing
light precip down there, so the 20% chance seems reasonable at this
time.  Temperatures remain near normal in the mid 30s to mid 40s
Friday and Saturday with northerly flow in the wake of the low.

The mid/upper-level pattern begins shifting east Saturday night into
Sunday which brings the ridge into the Plains and shifts the eastern
trough off the Atlantic Coast.  Low level flow swings around to the
southeast across the Mid Mississippi Valley Sunday afternoon which
is the beginning of a warm up next week.  The wind shift takes place
late enough in the day that highs will only be a few degrees warmer
than Saturday.  The real warm up comes Monday through Wednesday with
highs pushing into the mid 50s to low 60s.  However, the LREF
cluster analysis continues to show variability in this time period
as the mid/upper pattern shifts and becomes less amplified.
Temperature IQRs are still as much as 8-10 degrees so the
deterministic temperature forecast is fairly uncertain.  With that
in mind, even the 25th percentile temperatures for Monday though
Wednesday are warmer than the 75th to 90th percentile temperatures
for New Year`s Day through Sunday.  Therefore confidence that
temperatures will be warmer next week is high.


Carney

&&

.AVIATION...  (For the 06z TAFs through 06z Thursday Night)
Issued at 1052 PM CST Wed Dec 31 2025

A cold front is currently approaching KUIN from the north,
bringing with it a deck of low MVFR stratus ceilings and a switch
to north/northeasterly winds. This front is expected to reach
central Missouri and the metro terminals overnight by early
morning. Confidence is greatest in high IFR/low MVFR ceilings
reaching mid-Missouri and potentially persisting through the mid-
late afternoon tomorrow. Surface winds will become light and
variable as a weak surface high settles over the area tomorrow
evening and night.

Peine/Gosselin

&&

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

$$

WFO LSX