999
FXUS63 KLSX 291703
AFDLSX

Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
1203 PM CDT Wed Apr 29 2026

.KEY MESSAGES...

-Cool and largely dry conditions will prevail through Saturday.

-Temperature return to near normal Sunday and continue into next
week.


&&

.SHORT TERM...  (Through Late Wednesday Afternoon)
Issued at 141 AM CDT Wed Apr 29 2026

Light showers are still moving across the forecast area early this
morning, but as the mid-level shortwave responsible for them shifts
eastward, they will exit the forecast area before day break. An
elevated cold front is also sliding through the forecast area this
morning, ushering in a cooler and drier air mass that will stick
around into the first half of the weekend. This boundary is also
helping to shunt the lingering showers to the east. Today will be
seasonally cool under the influence of the new airmass, with high
temperatures peaking in the 60s area wide.

By Thursday the mid-level pattern will have shifted to its new
position that will persist through much of the forecast period. The
mid-level low will move from south-central Canada into the Great
Lakes region, and a mid-level ridge will build into and stall over
the Intermountain West. A subtle shortwave will push through the
west to northwesterly flow on Thursday, resulting in 20% chances of
showers and thunderstorms along a weak cold front dropping south
through the region Thursday into Friday. Confidence in widespread or
substantial rain is low, given the weakness of lift from aloft and
at the surface.

Delia

&&

.LONG TERM...  (Wednesday Night through Monday)
Issued at 141 AM CDT Wed Apr 29 2026

Thursday`s cold front will bring a reinforcing surge of cooler
air into the region for the weekend, with Friday on tap to be the
coolest day of the period. Ensemble guidance indicate highs on
Friday will be below 65 degrees area wide, with only a 20% chance
for high temperatures to exceed 60 degrees north of I-70. The
region is expected to be on the periphery of a surface high Friday
into Saturday. While this isn`t the most favorable position for
efficient overnight cooling, the cool airmass and proximity to
the surface high means we`ll have to keep an eye on the frost
potential Saturday morning. NBM probabilities of low temperatures
less than 37 degrees peak north of I-44 in Missouri and I-70 in
Illinois between 30-50%. While this isn`t a slam dunk frost
potential, we`ll have to continue to keep an eye on this as the
growing season continues to progress.

Dry conditions and below normal temperatures will continue on
Saturday before low-level flow becomes west to southwesterly and
warm air advection kicks up on Sunday. High temperatures will
jump around 10 degrees starting Sunday, and near normal
temperatures will persist into next week. Sunday and beyond the
mid-level pattern remains stagnant with the ridge over the
Intermountain West and the trough stalled over the eastern CONUS.
Multiple disturbances will pass through the northwesterly flow
across the mid- Mississippi Valley, reintroducing chances of
showers and thunderstorms to the forecast.

Delia

&&

.AVIATION...  (For the 18z TAFs through 18z Thursday Afternoon)
Issued at 1154 AM CDT Wed Apr 29 2026

Dry and VFR conditions are expected through the period. Northwest
winds will gust up to 20 knot this afternoon before turning light
and variable after 00Z tonight.

Britt

&&

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

$$

WFO LSX