677
FXUS63 KLSX 102339
AFDLSX

Area Forecast Discussion
National Weather Service St Louis MO
639 PM CDT Sat Oct 10 2026

.KEY MESSAGES...

- Near-record warmth is expected through the first part of the
  week.

- A stalled front brings multiple chances for showers and
  thunderstorms for the middle of the week.

- A stronger cold front brings cooler and drier weather for the
  weekend.

&&

.SHORT TERM /THROUGH SUNDAY/...
Issued at 237 PM CDT Sat Oct 10 2026

Upper ridging remains in place across the central and eastern
United States. This has led to our recent trend toward near
record heat for mid October. Isaias made landfall yesterday on
the Gulf coast, with its remnants currently spinning near
Birmingham, Alabama. While not close enough to provide any rain
to our area, high level cloudiness spilling out from the top of
the cyclone has caused a temperature gradient across our
forecast area this afternoon. Thicker clouds in the east have
led to temperatures 5-10 degrees cooler than yesterday, while
further west temperatures are once again approaching 90 degrees.

Clouds from Isaias pull away to the east tonight giving way to
another clear, calm night for most. Thus expect temperatures to
fall back to around 50 degrees in the cold spots by Sunday
morning. With even less clouds from Isaias on Sunday, the heat
returns to the entire area on Sunday afternoon. Some locations
rise 40 degrees from their morning lows up to around 90 in the
afternoon.

&&

.LONG TERM /SUNDAY NIGHT THROUGH SATURDAY/...
Issued at 237 PM CDT Sat Oct 10 2026

A trough currently moving into the Pacific Northwest will
gradually push back on the ridge over the coming days. While the
core of the trough lingers over the West Coast, a shortwave
trough ejecting east will help organize a cold front over the
Central Plains, moving southeast Monday into Tuesday. Ahead of
the front we remain firmly under the influence of the warm upper
ridge. With the addition of a southwesterly gradient wind ahead
of the approaching front we`ll see temperatures tick a degree
or two higher, especially in areas of downslope flow off the
Ozarks. There is a moist flow off the Gulf, but it`s a bit slow
to arrive in our area on Monday, likely leading to a period of
elevated fire danger. This is also likely to be our warmest day
of the week, with temperatures potentially approaching all time
October high temperature records in the mid 90s.

The front is slow to push through our area, as the driving
trough is pushing more east than south. It`s presence is more
likely to be felt in northern portions of the area on Tuesday
with some cooler weather behind it. However, the southern half
will see another hot day with temperatures near 90. NBM actually
has temperatures near all time record monthly highs again on
Tuesday, but this is on the extreme end of what`s possible.
Moisture should be increasing, with dewpoints approaching daily
record values near 70. It takes more energy to heat moist air
than dry air, so it will be harder to get as hot on Tuesday.
Add in a greater potential for cloud cover near the front, and
uncertainty on the speed of the front itself, and a more likely
forecast at this point is for the low 90s.

The front loses its push south and lingers over our area for a
couple of days. Meanwhile, shortwave troughs continue ejecting
east over the top of the remaining ridge, leading to multiple
rounds of showers and thunderstorms in the vicinity of that
front. The main periods look to be Tuesday night into Wednesday
and then again Wednesday night into Thursday. The severe weather
potential from this activity looks low at this point as wind
shear is weak to moderate and much of the thunderstorm activity
will be elevated. However, some locally heavy rain will be
possible considering the anomalous moisture near the boundary
(PW near climatological maximums for the time of year), the
general track of storms east along the boundary, and the
potential for multiple rounds.

Guidance sources are generally in good agreement on the timing
of the kicker front that comes in Thursday night into Friday,
ending our period of wet weather. What guidance sources disagree
on is the character of the air mass behind the front. It will be
cooler, that`s for sure. After all, we were near all time record
warmth for October ahead of it. However, just how cold is less
certain. Ensemble guidance varies largely by which parent model
system is being used. ECMWF guidance tends to be on the warmer
end, with the core of the cold air pushing more toward New
England. This leaves us cooler, but still near or even above
normal for mid October. The GFS tends to be on the colder side,
and the latest runs continue to come in even colder, sending the
core of the cold air right through the center of the country.
The GFS actually latches on to Polar air and crashes it south
all the way to the Gulf Coast. Under this colder scenario
freezing temperatures are possible.

The uncertainty is largely driven by the intensity and
amplitude of the trough driving this front and subsequently the
trajectory of cold air behind it. Looking at the LREF cluster
analysis, the warmer clusters contain almost no GEFS members and
feature 850mb temperatures this weekend as warm as +10C. The
colder clusters contain almost no ENS members and feature 850mb
temperatures as cold as -4C. The difference at the surface
assuming full mixing is highs in the 70s vs highs in the low
50s. And with the very low dewpoints being driven in by the
colder guidance, overnight lows would have the potential to drop
below freezing on a clear, calm night behind the front. Even
NBM is starting to show this with probability of temperatures
dropping below freezing rising to 10-20 percent by Sunday
morning area wide.

&&

.AVIATION /00Z TAFS THROUGH 06Z MONDAY/...
Issued at 636 PM CDT Sat Oct 10 2026

The only potential threat is river valley fog primarily at KSUS
late tonight. Otherwise, VFR flight conditions are expected
through the forecast period at the local terminals.

&&

.CLIMATE...
Issued at 237 PM CDT Sat Oct 10 2026

Very warm temperatures are expected over the next several days.
This will challenge daily record highs and record warm lows on
multiple occasions. The daily records threatened are shown
below.

Record High Temperatures:

October 10:
KSTL: 92/1963
KCOU: 92/1963
KUIN: 89/1963

October 11:
KSTL: 94/1963
KCOU: 89/1962
KUIN: 88/1962

October 12:
KSTL: 89/1890
KCOU: 94/1899
KUIN: 90/2024

October 13:
KSTL: 90/1899
KCOU: 95/1899
KUIN: 87/1975


Record High Minimum Temperatures:

October 12:
KSTL: 70/1997
KCOU: 69/1928
KUIN: 70/1928

October 13:
KSTL: 69/2008
KCOU: 69/1899
KUIN: 65/1935

October 14:
KSTL: 70/1899
KCOU: 67/2017
KUIN: 67/1920

In addition, all time monthly record high temperatures are
within range of being broken. The following are the October
monthly high temperature records at each site:

October Record High:
KSTL: 94 most recently on Oct 1, 2019
KCOU: 96 on Oct 7, 1939
KUIN: 96 on Oct 7, 1939

&&

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

&&

$$

SHORT TERM...Kimble
LONG TERM...Kimble
AVIATION...Elmore
CLIMATE...Kimble