752
FXUS63 KLSX 100944
AFDLSX

Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
444 AM CDT Fri Oct 10 2025

.KEY MESSAGES...

- Showers and a few thunderstorms are likely (50-70%) across
  northeast/central Missouri and west-central Illinois this
  morning, but severe storms are not expected. Some pockets of
  soaking rain are possible, but only for a limited area, and
  drought conditions will persist overall.

- Slightly above normal temperatures and largely dry conditions
  are favored for the next week, with only a few opportunities for
  light rain Monday and again later in the week.


&&

.SHORT TERM...  (Through Late Saturday Afternoon)
Issued at 303 AM CDT Fri Oct 10 2025

The most pressing item of interest during the short term period is
the approach of a cold front from the northwest this morning, which
is set to bring some scattered showers and a few thunderstorms to
parts of the area early in the day.

As of 3:00 AM, the actual surface boundary remained well to our
northwest and draped across eastern Nebraska and northwest Iowa.
Ahead of this front, numerous showers and weak thunderstorms have
developed across northwest Missouri and central Iowa, and this
activity is moving slowly southwest toward our area. This
convection is being fueled largely by warm air advection and
elevated instability, with between 500 and 1000 J/kg of MUCAPE
being analyzed by SPC mesoanalysis in this area. However, very
little effective shear exists in the storm layer, and this
activity is largely unorganized as of yet.

As we approach sunrise, at least a few of these storms are expected
to reach northeast Missouri and west-central Illinois, and may drift
as far south as central Missouri later in the morning. However,
almost all available guidance suggests that this elevated
instability will weaken as the day progresses, and very little in
the way of surface-based instability is projected to develop either.
Meanwhile, most CAMS do not maintain robust convection past mid-
morning, and most precipitation is expected to diminish by the time
it reaches as far southeast as the St. Louis metro area. Considering
the lack of wind shear and the diminishing instability with time,
severe thunderstorms are not expected. However, we can`t rule out a
few instances of small hail in northeast Missouri before storms
begin to weaken later in the morning. While some pockets of soaking
rain will be possible, this is not expected to be widespread, and
this rain is not likely to have a meaningful impact on drought
conditions.

Otherwise, the cold front is expected to slowly push through the
area and stall somewhere across southern Missouri and Illinois by
tonight and linger there through tomorrow. Considering that this
front will be weakening as it arrives and won`t feature strong cold
air advection behind it, temperatures today and tomorrow are likely
to be generally warm, with values in the low to mid 70s north of I-
70 and near 80 degrees across the Ozarks and southwest Illinois. No
additional precipitation is expected beyond this morning`s showers.

BRC

&&

.LONG TERM...  (Saturday Night through Thursday)
Issued at 303 AM CDT Fri Oct 10 2025

Following today`s cold front, the axis of an upper-level ridge will
slowly drift overhead by Sunday. Meanwhile, a large low pressure
system moving across the northern plains and upper Mississippi
Valley will drive southerly return flow, and the combination of
these factors will result in a modest warming trend Sunday and
possibly into Monday as well. As such, we can expect temperatures to
climb into the low 80s area-wide to end the weekend.

However, the temperature forecast gets a bit less certain Monday
onward due to the potential for additional cold fronts, similar to
the one we will see today. Sometime between Monday and Tuesday,
another cold front is likely to move into the area and stall. While
this front (and possibly others later in the work week) do not
appear to be particularly strong and will be fighting a persistent
upper level ridge, it does appear that this will help to slow our
warming trend a bit, especially in our northern areas. Still,
ensemble temperature spreads remain relatively large from early to
late next week, owning to timing and strength differences of the
various fronts among ensemble members.

Meanwhile, these cold fronts also maintain at least some modest
precipitation chances, although most of the mentionable (15% or
greater) precipitation chances remain just outside of our area in
the operational NBM and official forecast. We suspect that these
probabilities may be a bit too low, particularly on Monday, but
considering that even if rain does fall the amounts are likely to be
very light, we have opted to maintain the largely dry forecast for
now. In other words, while we may get some light rain at times
throughout the work week, drought conditions are very likely to
persist overall

BRC

&&

.AVIATION...  (For the 12z TAFs through 12z Saturday Morning)
Issued at 438 AM CDT Fri Oct 10 2025

The main concern during the 12Z TAF period is the potential for
showers and thunderstorms during the first 2 to 4 hours of the
period, primarily at UIN/COU/JEF. Numerous thunderstorms have
developed upstream as of 0930Z, and are slowly moving toward these
terminals. While this activity is likely to weaken as it reaches
each terminal, a few strikes of lightning and bursts of heavy rain
will be possible. This threat is highest at the very beginning of
the period, and will wane as the morning progresses. Some MVFR
clouds will also be possible throughout the day and into the
evening, but most model guidances keeps ceilings just above VFR
thresholds. Elsewhere, some patchy steam fog will again be
possible at SUS at the start of the period, but this is not
likely to last long after sunrise. Precipitation is not likely to
impact St. Louis area terminals.

Otherwise, some patchy steam fog will again be possible at SUS
and CPS overnight and early tomorrow morning, but the possibility
of lingering low clouds and warmer overnight temperatures limits
confidence that fog will develop.

BRC

&&

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

$$

WFO LSX