928
FXUS63 KLSX 141109
AFDLSX

Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
609 AM CDT Sun Sep 14 2025

.KEY MESSAGES...

- Hot weather will continue through the middle of this week.

- There is a slight chance (15 - 25%) of showers and thunderstorms
  each afternoon from today through Tuesday. Precipitation
  chances increase to 30 - 50% mid to late this week.


&&

.SHORT TERM...  (Through Late Monday Afternoon)
Issued at 328 AM CDT Sun Sep 14 2025

Mid-level ridging will continue to be the primary influence on our
sensible weather today through Tuesday. Expect highs in the 90s each
day. Monday and Tuesday will be a few degrees less hot than today as
a weak backdoor cold front ushers slightly cooler air into the
region and as we get increased mid-level cloud cover from a mid-
level trough to the west.

The mid-level trough over the central and northern Plains will
provide lift for isolated to widely scattered showers and
thunderstorms this afternoon into this evening. Deep layer shear
values will be lower than those of yesterday, only peaking at 10 -
15 kts. So although SBCAPE values will be on the order of 1500 -
2000 J/kg, a lack of appreciable shear will favor non-severe pulse
convection. Showers and thunderstorms are expected again Monday and
Tuesday afternoons. With the trough kicking out of the region and
the ridge expanding over the area, coverage will likely be more
isolated than today. Otherwise, fairly similar CAPE and shear values
warrant more pulse convection each day.Jaja

&&

.LONG TERM...  (Monday Night through Saturday)
Issued at 328 AM CDT Sun Sep 14 2025

The ridge finally erodes in the middle of this week as a trough dips
into the central CONUS. This feature will be responsible for a much
anticipated cooldown, but its slow-moving nature will drag the
transition out. Because of this, its only impact on Wednesday will
be increased chances of showers and non-severe thunderstorms in
Missouri that afternoon. More tangible and widespread rain chances
arrive on Thursday, though this should be characterized more as a
higher chance of light rain than a chance at drought relief. LREF
probabilities of receiving 0.25" of rain in 24 hours ending at 00z
Friday are still under 50%.

Thursday is also when cooler air will begin to filter into the
region. Confidence is increasing that a significant portion of the
northern and western CWA will see highs below 90 degrees beginning
Thursday with the rest of our counties following on Friday. Despite
the sub-90 highs, it likely won`t be until next weekend that we
return to near seasonal average highs region-wide.

Jaja

&&

.AVIATION...  (For the 12z TAFs through 12z Monday Morning)
Issued at 605 AM CDT Sun Sep 14 2025

VFR conditions with light, variable winds will prevail through the
TAF period.

There is a slight chance of isolated showers and thunderstorms
this afternoon areawide and overnight mainly west of the
Mississippi River. Confidence in direct impacts to terminals is
still too low to mention in the TAFs. If a thunderstorm does hit a
terminal, expect brief downpours and gusty winds.

Jaja

&&

.CLIMATE...
Issued at 218 PM CDT Wed Sep 10 2025

Record daily highs Friday 9/12 through Monday 9/15:

    9/12 | 9/13 | 9/14 | 9/15
STL   98    100    101    101
COU  100     99    104    101
UIN   99    100     99    100

Delia


&&

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

$$

WFO LSX