923
FXUS63 KLSX 231723
AFDLSX

Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
1123 AM CST Sun Nov 23 2025

.KEY MESSAGES...

- Widespread beneficial rainfall is expected Monday/Monday night
  and again next weekend.

- Dry weather along with seasonably cold temperatures is forecast
  Wednesday through Friday.


&&

.SHORT TERM...  (Through Late Tonight)
Issued at 250 AM CST Sun Nov 23 2025

A weak cold front is currently located across western Illinois
and eastern Missouri. Behind this front, winds turn out of the
northwest. Low-level cold air advection is fairly weak however
with the incoming air mass of Pacific origin. This means that
highs today actually will be a bit warmer for most locations
compared to yesterday. The one (big) fly in the ointment is low
stratus. Current GOES-19 nighttime microphysics imagery shows
quite a bit of stratus in south central and southeast Missouri.
The stratus is still expanding with time, which means it may
impact more parts of the area over the next few hours. Near-term
model guidance isn`t handling this area of stratus particularly
well. The low-level flow should veer more to the northwest which
may help advect the stratus back out of central/east central
Missouri this morning. Winds at 925-950 hPa become lighter and
actually turn out of the southwest again by midday. This could
mean the low clouds linger well into the afternoon in parts of
central, east central, and southeast Missouri. This lingering of
the stratus is also supported by the cloud thickness product from
GOES-19. This derived product shows the stratus ranges from about
800-1300 feet thick. The thicker portions of the stratus should be
slow to lift/scatter out and should persist into the afternoon
hours given the weak sun angle of late November. Because of the
concern that low stratus may linger into the afternoon, did cool
high temperatures a few degrees. This may not be cool enough
either, with some spots potentially struggling to hit the 50
degree mark. Overall however, highs are expected to be in the mid
to upper 50s for most locations.

A mild night is in store tonight as mid/high level clouds increase
from west to east ahead of the next weather system, which will
impact the area early in the work week. South/southeasterly winds
will also gradually increase overnight, helping to keep temperatures
up. Lows are forecast to range from the upper 30s (south-central
Illinois) to the mid 40s central/east central Missouri. Those values
would be close to 10 degrees above normal for the date.


Gosselin

&&

.LONG TERM...  (Monday through Saturday)
Issued at 250 AM CST Sun Nov 23 2025

(Monday - Monday Night)

Chances of rain increase dramatically on Monday as a strong midlevel
shortwave trough moves out of the south-central Plains early Monday
afternoon. Concurrently, moisture advection strengthens during the
day and peaks Monday evening on the nose of a 30-35 knot low-level
jet. Widespread light, to perhaps moderate, rain will impact the
entire region. The best temporal window for rain is expected to be
the afternoon/evening hours. Total rainfall amounts of 0.25-0.50"
are forecast, which closely matches the latest LREF probabilities.
Chances for at least 0.25" have held steady around 50%, but drop off
into the 10-20% range for more than 0.50".


(Tuesday - Friday)

A secondary mid/upper level trough is forecast to move across the
Upper Midwest into the Great Lakes late Tuesday/Wednesday. Ahead of
this feature, a surface low will also move across the Great Lakes,
with an attendant cold front sweeping through the mid-Mississippi
Valley Tuesday afternoon/evening. Behind this front a Canadian air
mass will infiltrate the region. This incoming air mass does not
look terribly impressive for late November standards, characterized
by 850-hPa temperatures around -4 to -6C (20-25th percentile) and a
surface anticyclone near 1030 hPa (90-95th percentile). The spread
in ensemble guidance has continued to decrease with respect to
temperatures, generally showing lows in the 20s and highs in the 40s
in/around the Thanksgiving holiday. These readings are seasonably
chilly, generally about 4-7 degrees below normal day and night. Dry
weather is also forecast in/around the Thanksgiving holiday, which
is good news for holiday travelers.


(Friday Night - Saturday)

Another midlevel shortwave trough is expected to move out of the
south-central Plains sometime late Friday into Saturday. Ensemble
guidance varies with the timing/track of this feature, but
indications are that another widespread precipitation event is
likely to unfold by next weekend. LREF probabilities for measurable
precipitation ending Saturday evening are now in the 60-80% range.
At this time, the vast majority (if not all) of this should fall as
a cold rain as low-level warm air advection increases with time.
However, wetbulbing may provide a window for snow to be the primary
precipitation type within a few hours after onset. A very brief
transitory period of sleet may also be possible given the dry low
levels likely to be in place. The best chance (~10%) of snow would
be in our far north, but we will have to watch how things trend over
the next several days. That being said, there is little/no signal
for any significant wintry precipitation at this time, but a few
hours of snow with minor accumulations may occur with a further
south track of the system and/or the air mass coming in later this
week being colder and drier than currently forecast.


Gosselin

&&

.AVIATION...  (For the 18z TAFs through 18z Monday Afternoon)
Issued at 1110 AM CST Sun Nov 23 2025

While fog has lifted at KUIN and the terminal has returned to VFR
flight conditions, the remainder of the area is still socked in
with IFR fog and/or stratus. Fog will continue to lift through
the day, through stratus is expected to stick around through the
end of the day, eroding around the edges. The exception is KSTL,
as the clearing line slowly advances southwest to the terminal
space. KSTL is expected to pop up to VFR conditions around 18Z.


IFR/MVFR stratus will build back in tonight along southerly flow,
taking over all the terminals and keeping flight conditions
reduced through the end of the TAF period.

A weather system will approach the area tomorrow afternoon after
the TAF period, bringing widespread light to moderate rain to the
region.

Delia

&&

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

$$

WFO LSX