Area Forecast Discussion

662
FXUS63 KLSX 111129
AFDLSX

Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
529 AM CST Sun Jan 11 2026

.KEY MESSAGES...

- After a cold day today, a warm up brings mild temperatures
  Monday and Tuesday.

- Multiple cold fronts later this week initiate a trend back
  toward colder temperatures beginning Wednesday.


&&

.SHORT TERM...  (Through Late Monday Afternoon)
Issued at 217 AM CST Sun Jan 11 2026

Cold advection behind last night`s cold front has brought in the
coldest air we`ve seen in about a week. But the core of the cold
advection will be over Illinois this morning, shifting east this
afternoon. So despite a cold start, we actually warm back up close
to normal for afternoon highs in the upper 30s to near 40. The wind
relaxes as well as surface high pressure nudges into the area. After
another seasonably cold night tonight, winds shift to west and
initiate a warm up on Monday. Highs Monday will be some 10 to 15
degrees warmer than today, in the upper 40s to mid 50s.

Kimble

&&

.LONG TERM...  (Monday Night through Saturday)
Issued at 217 AM CST Sun Jan 11 2026

The upper air pattern through most of this week and into the weekend
features some variation of northwest flow between a ridge over the
West Coast and troughing in the east. That opens the central US up
to Arctic air masses spilling out of Canada with daily variations in
temperature based on the passage of multiple fronts driven by
shortwave troughs in the broader eastern trough. The first trough
drops into the Upper Midwest on Tuesday, driving a surface low
through the Great Lakes and a cold front southward through our
region. Ahead of the front it remains mild. In fact, Tuesday should
be even warmer than Monday. NBM probability of 60+ degrees reaches
50 to 70 percent south of the Missouri River. The front arrives
Tuesday night, but the core of the cold air lags behind into the day
Wednesday. So some areas will see highs in the morning before a
gusty north wind pushes the temperature back down later in the day.
Up to 50 percent of low resolution ensemble members produce rain in
the vicinity of the trough/cold front Tuesday night into Wednesday,
but moisture is lacking as Gulf moisture remains blocked. So any
rain that falls will be quite light. Less than 20 percent of members
produce 0.05 inches.

Beyond midweek there`s greater variance in ensemble guidance on the
evolution of the overall trough and the waves embedded in it. This
creates some greater day to day uncertainty in the temperature
forecast especially as we head into the weekend. But the overall
trend is fairly clear. After a cold Thursday there`s a bit of a
rebound before another front brings renewed cold air for the
weekend. The evolution of the shortwave troughs and the resulting
impact on the trajectory and intensity of the cold air surge will
determine whether we see a brief dip back below normal or a more
intense drop well below normal. While we can`t rule out a brief
period of light precipitation associated with one of the embedded
troughs, Gulf moisture remains blocked until later in the weekend so
any precipitation would be light.

Kimble

&&

.AVIATION...  (For the 12z TAFs through 12z Monday Morning)
Issued at 527 AM CST Sun Jan 11 2026

Some broken stratus is likely to impact KUIN over the next 1-2
hours, but ceilings should stay at or above 3 kft AGL. Northwest
winds will gradually lessen this morning/early afternoon, with
gusts diminishing from west to east this morning. Winds are then
expected to go light/variable this afternoon/evening as a surface
ridge moves across the region.

Gosselin

&&

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

$$

WFO LSX

NWS LSX Office Area Forecast Discussion