171
FXUS63 KLSX 232332
AFDLSX

Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
632 PM CDT Thu Apr 23 2026

.KEY MESSAGES...

-  A round of showers and thunderstorms (70-90% chance) will move
   across the area tonight into Friday morning. Scattered thunderstorms
   are expected, with a limited potential for isolated damaging
   wind gusts and locally heavy rain. Overall though, the
   potential for severe storms is low.

- Another round of showers and thunderstorms is expected (70-80%)
  late Sunday through Monday with the potential for a few strong
  to severe thunderstorms.


&&

.SHORT TERM...  (Through Late Friday Night)
Issued at 256 PM CDT Thu Apr 23 2026

The latest surface analysis is showing a front extending from a
surface low over south central Canada into eastern Nebraska and
Kansas.  Severe thunderstorms area have already developed ahead of
this front over western Iowa and eastern Nebraska and will continue
develop southward into Kansas in the highly unstable/sheared
environment.  These storms will continue to consolidate into a line
as they are pushed east by the cold front in response to a mid-level
trough currently over the central High Plains.  While this line will
continue to pose a risk for tornadoes, large hail, and damaging
winds over western Missouri, the RAP is showing that the front will
become aligned with the 0-3km/0-6km shear vectors later this evening
and overnight which will aid in helping the storms become more cold
pool dominated.  This is seen in the CAMS and is reflected well in
the SWODY1 which has the northwest half of the CWA in a marginal
risk with mainly low end (5%) damaging wind probabilities. This
warrants keeping our messaging for a few strong to severe
thunderstorms with the main threat being damaging winds with one or
two brief tornadoes in this same area. Otherwise with the ascent
associated with the mid-level trough, will keep the going 70-90%
PoPs for late this evening into Friday morning with lower PoPs (40-
60%) tomorrow afternoon as the attendant front lingers over
southeast Missouri and southwest Illinois.


Britt

&&

.LONG TERM...  (Saturday through Next Thursday)
Issued at 256 PM CDT Thu Apr 23 2026

Friday night and Saturday looks dry before rain chances begin to
increase as soon as Sunday when the global models are showing
another trough moving through the central CONUS.  While the global
models are showing differences in the timing of this shortwave, the
consensus of the LREF is to have the highest PoPs (30-50%) over the
western half of the CWA.  Then concern increases Sunday night into
Monday night as model guidance is showing a pronounced trough moving
across the upper Midwest with an attendant cold front moving across
the CWA on Monday afternoon.  At this time it appears that there
will be a round of showers and thunderstorms moving across the area
on Sunday night in advance of warm front on the nose of a low level
jet.  Once the warm front moves north of the warm front, there will
the potential for severe thunderstorms Monday into Monday evening in
the open warm sector with the LREF showing anywhere from 500 J/kg
(25th percentile) to 2500 J/kg (75th percentile) SBCAPE with around
50 knots of deep layer shear ahead of the cold front.  Of course
there does remains questions this far out including how long will
clouds and rain from the morning round of thunderstorms will linger
over the area which could stabilize the environment.  In addition,
the timing of the upper trough could change which will determine
when any severe weather will happen.

Additional shortwaves will move across the area mid to late next
week bringing additional chances for showers and thunderstorms.
Temperatures will be at or above normal.

Britt

&&

.AVIATION...  (For the 00z TAFs through 00z Friday Evening)
Issued at 627 PM CDT Thu Apr 23 2026

A line of showers and thunderstorms will move east through the
CWA tonight. Timing and trends have stayed consistent, so few
changes were made to the previous TAFs during this update. It
remains true that any terminal that takes a direct hit by a
thunderstorm may experience IFR ceilings and visibilities and wind
gusts of 35+ kts. MVFR ceilings will move in behind the system and
will prevail for much of Friday morning.

Jaja

&&

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

$$

WFO LSX