Area Forecast Discussion

862
FXUS63 KLSX 172323
AFDLSX

Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
623 PM CDT Sat May 17 2025

.KEY MESSAGES...

- The chance for strong to severe thunderstorms returns to the
  region Sunday night into Monday and again Monday afternoon and
  evening.


&&

.FORECAST DISCUSSION... (Through Next Saturday)
Issued at 201 PM CDT Sat May 17 2025

An active pattern returns to the region Sunday into the beginning of
the work week. A mid-level disturbance moving into the mid-
Mississippi Valley along southwesterly flow will initiate and
organize an MCS that will track east overnight along a warm front
that will be draped across the mid-Mississippi Valley. 1500-2500
J/kg of MUCAPE and 40-60kts of 0-6 km shear will also help
contribute to its organization and maintenance, as well as
provide fuel and organization for individual thunderstorms within
the MCS to become strong to severe. The best location for strong
to severe thunderstorms will be over western and central Missouri
where instability is expected to be highest, most deterministic
guidance sources show instability waning considerably across
eastern Missouri and western Illinois. The main concerns are hail
and winds as these storms are expected to be elevated.

Another mid-level shortwave disturbance will move into the region
Monday afternoon and evening, producing another round of
thunderstorms across the mid-Mississippi Valley. Instability is
expected to be able to rebound back to 1000-3000 J/kg of MUCAPE by
the afternoon hours in the wake of a northward moving warm front.
All hazards are possible with thunderstorms that become strong to
severe.

Delia

&&

.AVIATION...  (For the 00z TAFs through 00z Sunday Evening)
Issued at 614 PM CDT Sat May 17 2025

Gusty winds will subside this evening with light and variable
surface flow overnight. The one exception will be KUIN, where
winds may remain a few knots higher. VFR conditions are likely to
hang on around the metro terminals and KUIN through the end of the
TAF period.

Active weather returns in the form of showers and thunderstorms
that approach out of the southwest late Sunday. Differences in
timing and position of the warm front are somewhat uncertain with
precipitation probabilities peaking around 40 percent around KCOU
and KJEF late Sunday. SHRA/TSRA was left out of the prevailing
groups considering the low probabilities and potential that
arrival lands near the end of the TAF period.

Maples

&&

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

$$

WFO LSX

NWS LSX Office Area Forecast Discussion