858
FXUS63 KLSX 132305
AFDLSX

Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
505 PM CST Thu Nov 13 2025

.KEY MESSAGES...

- Unseasonable warm temperatures are expected through Saturday.

- There are signals for a wetter pattern to develop mid/late next
  week, but details are highly uncertain.


&&

.SHORT TERM...  (Through Late Friday Afternoon)
Issued at 221 PM CST Thu Nov 13 2025

Latest surface analysis shows a ridge east of the Mississippi
River early this afternoon. This feature will continue to push
eastward overnight, with southerly return flow gradually
increasing. The combination of increasing clouds and southerly
surface winds is expected to yield a mild night with lows only
dropping back into the mid 40s to low 50s. These values would be
about 10 degrees above normal for the date.

The first of two unseasonably warm days is expected on Friday. Low-
level warm air advection continues to increase throughout the day,
along with decreasing clouds and seasonably deep mixing (to near 850
hPa). This all points toward a warm day. High temperatures are
forecast to climb into the mid 70s. These values would be nearly 20
degrees above normal, though should fall at least a couple degrees
below records for the date.


Gosselin

&&

.LONG TERM...  (Friday Night through Next Thursday)
Issued at 221 PM CST Thu Nov 13 2025

(Friday Night - Saturday)

Unseasonable warmth will continue heading into early this weekend.
The air mass in place is very impressive, characterized by 850-hPa
temperatures of +17 to +19C (near daily records). A very warm start
to the day (lows in 50s to near 60 degrees) and surface winds
veering more to the west/southwest are also very favorable for
anomalous warmth. West/southwest flow downslopes off of the eastern
Ozarks, which could lead to highs maybe even approaching the 80
degree mark in eastern Missouri. A couple of limiting factors
mentioned yesterday still exist however, namely some mid/high level
clouds and more limited mixing (to near 875-900 hPa). Those two
factors are likely to prevent record highs (KSTL: 81F, KCOU: 78F,
KUIN: 75F) from occurring, but I wouldn`t rule it out either. A
favorable timing of the front and the aforementioned downslope winds
suggest at least the possibility that KSTL and KCOU may end up
threatening these records.


(Saturday Night - Sunday Night)

A period of cooler (and much drier) weather will move into the
region behind Saturday`s cold front. Precipitation chances
associated with the front look minimal given weak moisture return
ahead of the boundary and stronger mid/upper level forcing for
ascent staying well to our east/northeast. The LREF for reference
has <5% probability for measurable precipitation.

Temperatures on Sunday get back into the mid 50s to low 60s. While
some 15+ degrees cooler than Saturday, those values still would be a
few degrees above normal.


(Monday - Next Thursday)

Ensemble guidance is in better agreement with respect to the early
week system. Both the EPS/GEFS agree that a piece of the
southwestern CONUS closed low will eject out into the central Plains
by Monday. There are however some subtle differences with
timing/track that still need to be ironed out in the coming days.
Rain chances (40-60%) increase Monday afternoon/night associated
with this system. However, the chances for more significant rainfall
appear low. Probabilities on the LREF for even 0.10" of rain only
peak out in the 30-50% range, and quickly fall below 30% for at
least 0.25".

Uncertainty with respect to temperatures remains extremely high on
Tuesday. How strong and exactly where the system tracks
Monday/Monday night will play a huge role. The GFS/GEFS generally is
further south while the ECWMF/EPS is further north. With a very
tight north-south oriented temperature gradient, that means huge
differences regionally. The GFS/GEFS would favor highs in the
40s/50s while the ECWMF/EPS suggests highs in the 60s/70s. This
continues to be well reflected by the probabilistic suite of the
NBM. The spread between the 25th/75th percentiles is 25+ degrees,
with differences between the 10th/90th around 35 degrees. My hunch
is that the cooler GFS/GEFS is more likely to be correct given the
pattern as Monday/Monday night`s system should be able to coax the
boundary further south. There also isn`t a strong ridge across the
southeastern CONUS, which would help hang the front up further to
the north. Furthermore, guidance has quite a bit of mid/upper level
confluent flow across the Upper Midwest. This suggests a surface
high in that region, which would also be able to coax cooler, drier
northeast flow into the region. The high spread in temperatures
continues Wednesday/Thursday as well, but highs may tend to stay
closer to the 25th percentile of the NBM if the front does indeed
stay to our south. In the absence of a stronger midlevel impulse
inducing cyclogenesis to our west (which is possible though), it is
difficult to see the front moving much poleward.

Forecast uncertainty remains high for mid/late next week as well in
terms of precipitation chances/amounts. The overall pattern
(anomalous troughing in the southwest) suggests the potential for a
wet pattern across the Mississippi Valley, but it is way too early
for any specifics. The good news (from a drought perspective) is
that there looks to be multiple chances for beneficial rainfall
mid/late next week. Five-day precipitation anomalies on both the
GEFS/EPS are in the 0.5-1.0" range. Given the ongoing
dryness/drought, multiple rounds of rain would be very beneficial.
One note of caution however is the fairly extreme model volatility
that has been occurring the past several days. This gives me some
pause and lowers overall confidence in saying definitively that it
looks like a wet and active period.


Gosselin

&&

.AVIATION...  (For the 00z TAFs through 00z Friday Evening)
Issued at 505 PM CST Thu Nov 13 2025

Dry and VFR flight conditions will persist this TAF period with only
the potential for some low-VFR clouds early Friday morning through
evening. A modest southwesterly low-level jet will overlay the
region overnight into Friday morning as well, but associated LLWS is
forecast to be weak and without significant impact. Winds will
remain light and southeasterly tonight, veering to southwesterly
Friday.

Pfahler

&&

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

$$

WFO LSX