Area Forecast Discussion

538
FXUS63 KLSX 260940
AFDLSX

Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
340 AM CST Mon Jan 26 2026

.KEY MESSAGES...

- Another Cold Weather Advisory is in effect tonight in south-central
  and southwest Illinois. Regardless of headline, conditions will
  be dangerously cold areawide and precautions should be taken to
  avoid hypothermia and frostbite.

- Dry conditions with mostly sub-freezing temperatures will
  persist through the end of the week.


&&

.SHORT TERM...  (Through Late Tuesday Afternoon)
Issued at 308 AM CST Mon Jan 26 2026

Despite the brutally cold start to the day, highs this afternoon
will climb into the teens as the Arctic airmass in place presses
east and alleviates us from the core of the cold. Insolation will
try and help, too, but efforts to warm will be mitigated by the
fresh, deep snowpack. The biggest impact of today`s sunshine may be
its ability to crust the snowpack over and dampen the potential for
blowing snow as winds increase tonight ahead of an approaching cold
front. These increased winds paired with cold air temperatures will
tank wind chills again tonight, warranting a Cold Weather Advisory
in portions of south-central and southwest Illinois.

Tuesday`s cold front will be weak. There won`t be much cold air
behind it, and an overwhelming lack of moisture will result in a dry
passage. In fact, southwesterly low-level winds ahead of the front
will be more impactful to our sensible weather as highs Tuesday
afternoon shoot into the 20s and 30s. Portions of southeast Missouri
even have a 30-40% chance of climbing above freezing according to
HREF probabilities. As high pressure moves in behind the cold front,
another night of efficient radiational cooling will be possible.
Temperatures are forecast to drop into the -5 to +5 degree range
with wind chills 5 to 10 degrees cooler. This nightly forecast will
hold pretty consistently through the end of the work week.

Jaja

&&

.LONG TERM...  (Tuesday Night through Sunday)
Issued at 308 AM CST Mon Jan 26 2026

Without a lack of any potent cold air advection, Wednesday will be a
similar day as Tuesday. The "warmth" will be disturbed late in the
week as another rush of Arctic air spills into the Mid to Upper
Midwest. The anomalously strong surface high (97.5th percentile of
climatology) associated with this airmass is forecast to pass
somewhere near if not in the Mid-Mississippi Valley this weekend.
Its proximity will dictate how efficiently we cool Friday and
Saturday mornings and which morning will be the coldest. The 01z NBM
shows that our current forecast low actual temperature at KSTL of -2
degrees sits solidly at the 50th percentile with a 20-30% chance of
achieving -5 degrees. If this trends cooler, we may be approaching
record lows yet again this week with equally as brutal wind chills
as we`ve seen this morning.

Ahead of the airmass, a weak clipper may bring some light snow into
the region Thursday into Friday. With very limited moisture in
place, the system would have trouble squeezing out any accumulating
snowfall. LREF probabilities of 0.01" of liquid precipitation over
24 hours ending Friday morning top out at only 30%, corroborating
our currently dry forecast. Granted, with how cold roads will be if
anything does fall it will stick, and anything that melts will be
subject to refreezing. This also holds true for snow that`s already
on the ground. Slick spots will be possible all week from potential
melting and refreezing from old and potentially new snow.

Another chance for light precipitation exists this weekend, but
differences in guidance make this impossible to talk in depth about
at this time range. With trends pointing to late weekend warming,
precipitation type may not necessarily be snow depending on when the
system moves through and how much warming we actually see. What is
certain is that moisture will still be at a premium, so the system
will have a tough time squeezing out anything measurable if it
precipitates here at all.

Jaja

&&

.AVIATION...  (For the 12z TAFs through 12z Tuesday Morning)
Issued at 338 AM CST Mon Jan 26 2026

Dry and VFR conditions are forecast through the TAF period.
Northwesterly winds today will back to southwesterly this
afternoon before becoming gusty tonight and gradually veering
ahead of a cold front.

Jaja

&&

.LSX WATCHES/WARNINGS/ADVISORIES...
MO...Extreme Cold Warning until noon CST today 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 until noon CST today for Audrain MO-Boone
     MO-Knox MO-Lewis MO-Marion MO-Monroe MO-Pike MO-Ralls MO-
     Shelby MO.

IL...Extreme Cold Warning until noon CST today 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 6 PM this evening to 6 AM CST Tuesday
     for Bond IL-Clinton IL-Fayette IL-Macoupin IL-Madison IL-
     Marion IL-Monroe IL-Montgomery IL-Randolph IL-Saint Clair
     IL-Washington IL.

     Cold Weather Advisory until noon CST today for Adams IL-Brown IL-
     Pike IL.

&&

$$

WFO LSX

NWS LSX Office Area Forecast Discussion