909
FXUS63 KLSX 200456
AFDLSX

Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
1056 PM CST Wed Nov 19 2025

.KEY MESSAGES...

- Showers and thunderstorms are expected late tonight into
  Thursday across southern Missouri. The warm front causing this
  rain will move north Thursday night into Friday which will cause
  the rain to overspread the entire area. Rain is now expected to
  end Friday night.

- Above normal temperatures are expected into early next week.


&&

.SHORT TERM... (Through Friday Night)
Issued at 328 PM CST Wed Nov 19 2025

Increasing low level southerly flow ahead of a low developing over
the Plains will push a warm front from Arkansas late tonight into
Thursday.  Guidance is showing weak to moderate low level moisture
convergence overspreading much of southern Missouri area ahead of
the warm front late tonight into Thursday morning.  Most CAMs
develop widespread convection, primarily south of the I-70 corridor
after 06Z tonight, and all of the deterministic models print out QPF
in this area as well.  Therefore have leaned heavily on the consensus
of the CAMs for PoPs tonight into Thursday morning which gave me 60-
90% across the eastern Ozarks into southwest Illinois heading into
Thursday morning, tapering to 20-50% farther north to the I-70
corridor.

Persistent southerly flow will continue to push the warm front
north to near the Missouri/Iowa border Thursday night. Moisture
convergence in the vicinity of the front will continue to produce
rain Thursday night into Friday.  Models show the Great Plains low
finally moving east through the Mississippi Vally Friday night.  Low
level flow turns more westerly just ahead of the low which shuts off
much of the moisture convergence and finally brings an end to the
rain.  The latest storm total QPF through Friday night ranges from
around 0.7 inches in northeast Missouri up to around 2 inches across
the eastern Ozarks. Temperatures south of the warm front on Thursday
and Friday will be milder than today, mainly in the upper 50s and
60s.

Carney

&&

.LONG TERM... (Saturday through Next Wednesday)
Issued at 328 PM CST Wed Nov 19 2025

The deterministic GFS and ECMWF are in remarkably good agreement
in the medium range.  Both models start Saturday morning with a mid-
upper level cut off low just southwest of California in the eastern
Pacific.  The low begins filling in and moving eastward over the
weekend and makes it to the Central Plains by Monday morning.
Guidance diverges somewhat by Tuesday with the GFS about 6 hours
faster moving the now open wave through the Mississippi Valley.
Then, a strong northern stream short wave digs into the Northern
Plains/Upper Midwest Tuesday night.  The surface reflection of the
wave drives a cold front through Missouri and Illinois late Tuesday
night or Wednesday.

Temperatures for Saturday through Tuesday look mild with highs
running around 5 to 12 degrees above normal in the mid 50s to low
60s. Lows will also be relatively warm in the upper 30s to mid 40s
which ranges from about 5 to 15 degrees above normal.  The
aforementioned timing differences manifest themselves in increasing
uncertainty in temperatures next week particularly on Wednesday with
the cold front.  High temp IQRs increase from 3 degrees over the
weekend up to 7-8 degrees Monday and Tuesday and up to 9-10 degrees
on Wednesday.  One thing looks fairly certain, the airmass behind
the Tuesday night/Wednesday cold front looks much colder, and
temperatures beyond Wednesday should fall well below normal.

The Monday/Monday night time frame looks like our
wettest period but the timing differences with respect to the
passing of the southern stream short wave make narrowing down that
window difficult.  Most members of the LREF are clustered around the
06Z-12Z Tuesday time frame so the highest PoPs (40%-60%) PoPs Monday
night in the NBM look reasonable.  The Monday/Tuesday system scours
most of the moisture out of the atmosphere, so Wednesday`s FROPA
should be largely dry with perhaps just a few sprinkles.

Carney

&&

.AVIATION...  (For the 06z TAFs through 06z Thursday Night)
Issued at 1045 PM CST Wed Nov 19 2025

Low clouds with ceilings between 700-1200 feet AGL at
UIN/STL/SUS/CPS are expected to all drop to IFR overnight.
Conditions have temporarily improved to VFR at COU/JEF, but are
expected to drop back to MVFR and eventually IFR by 09Z. Fog is
also likely to develop at all of the terminals after 09Z, with
visibilities dropping into the 1-3SM mile range, possibly lower,
before improving after 14Z. There may be some slow improvement on
Thursday, but ceilings will likely stay IFR through the period.
There will be an increasing chance of rain through the day, with
rain becoming predominant and lowering visibilities to MVFR after
00Z on Thursday evening.

Britt

&&

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

$$

WFO LSX