Area Forecast Discussion
652
FXUS63 KLSX 272315
AFDLSX
Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
515 PM CST Tue Jan 27 2026
.KEY MESSAGES...
- A Cold Weather Advisory has been issued for parts of south
central Illinois tonight an Wednesday morning. Wind chill
readings between -10 and -15 are expected.
- After some relatively warmer temperatures Today and Wednesday,
colder air will return to the area on Thursday. Dangerously cold
wind chill readings are possible Friday and Saturday mornings.
&&
.SHORT TERM... (Through Late Wednesday Afternoon)
Issued at 242 PM CST Tue Jan 27 2026
The country is locked in an amplified upper level pattern with long
wave troughing over the eastern U.S. and ridging over the west. This
results in persistent northwest flow aloft over the Central U.S.
which keeps below normal temperatures in the forecast through the
short term. Northwest surface winds this afternoon will become
light and variable tonight as a weak surface ridge moves south
through Missouri and Illinois. Guidance is indicating there will
be some mid- level clouds this evening, but the sky should be
mostly clear by 07- 09Z. Snow cover, light and variable winds, and
a clear sky adds up to excellent radiational cooling conditions
overnight. Wednesday morning`s lows therefore look 5-10 degrees
colder than this morning ranging from around -5 in south central
Illinois to around +5 in central Missouri. With the colder
temperatures in south central Illinois, wind chill values drop to
-10 to -15, have therefore issued a Cold Weather Advisory for late
tonight and Wednesday morning.
The surface ridge will be south of the CWFA by Wednesday morning. A
relatively clear sky over most of the area and west-southwest
surface flow should produce a good diurnal warm up after the
morning lows. However, even with a 25-30 degree rise in
temperatures, most locations will likely not get above freezing.
Areas of the eastern Ozarks will have the best chance to warm
above freezing into the mid 30s as current guidance indicates
they`ll have full sunshine along with the west-southwest flow. The
rest of the area will likely only get into the mid 20s to around
30.
Carney
&&
.LONG TERM... (Wednesday Night through Next Tuesday)
Issued at 242 PM CST Tue Jan 27 2026
The amplified upper level pattern persists through the extended. A
procession of short waves move southeast through the Mississippi
Valley, each one pulling a reinforcing shot of cold air into the
area. The deterministic ECMWF and GFS are in good agreement with
the timing of these waves. The first moves through Thursday into
Thursday night. They both show a bit of warm advection ahead of the
wave, and they also spit out a few hundredths of QPF. However,
nearly 80 percent of the LREF members remain dry during this period,
so have opted to keep the Thursday/Thursday night forecast dry.
Another much stronger wave moves through the Midwest into the deep
south Friday into Saturday. This wave pulls another 1040+mb Arctic
airmass into the Plains Saturday. Current indications are that air
temperatures will fall to near zero Saturday morning with wind chill
values of -10 to -15 across much of the area. The GFS also hints at
some flurries Friday night as the wave passes overhead, but more
than 90 percent of the LREF members are dry so have continued the
dry forecast.
Two more upper level waves drop south through the Eastern Plains and
Midwest, one right behind the other in the Sunday/Monday time frame.
These waves will bring us the best chance for precipitation through
the next 7 days. NBM PoPs have increased to chance category on
Sunday and Sunday night as the northern wave moves across the
Midwest, and both the GFS and ECMWF are spitting out some light QPF.
Chance PoPs look reasonable as around 60 percent of the LREF members
remain dry during this period. If any precip does fall, guidance
suggests it will be cold enough that it will be snow. The pattern
shifts east Monday into Tuesday with an upper level ridge building
across the Midwest. This signals warming temperatures, however
there is significant uncertainty evident in the ensembles. LREF
high temperature IQRs increase from 5 degrees on Monday to 11
degrees on Tuesday. Regardless...the signal is for warmer weather
early next week with temperatures rising above freezing across most
of the area by Tuesday.
Carney
&&
.AVIATION... (For the 00z TAFs through 00z Wednesday Evening)
Issued at 513 PM CST Tue Jan 27 2026
Dry and VFR conditions are expected through the period. Northwest
winds will become light this evening before turning out of the
west on Wednesday morning.
Britt
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...None.
IL...Cold Weather Advisory from 1 AM to 9 AM CST Wednesday for Bond
IL-Clinton IL-Fayette IL-Macoupin IL-Marion IL-Montgomery
IL.
&&
$$
WFO LSX
NWS LSX Office Area Forecast Discussion