304
FXUS63 KLSX 010746
AFDLSX

Area Forecast Discussion
National Weather Service Saint Louis MO
246 AM CDT Mon Sep 1 2025

.KEY MESSAGES...

- Largely dry and comfortable conditions continue through
  Wednesday morning before a strong cold front mid-week. Along
  with showers and a rumble of thunder, the front will usher in a
  notable cooldown through early next week.

&&

.SHORT TERM...  (Through Late Tuesday Afternoon)
Issued at 245 AM CDT Mon Sep 1 2025

Dry air is advecting west amidst weak but persistent easterly
near- surface flow as we enter climatological Fall. While mid-
level forcing continues to stimulate weak showers across western
Missouri, the dry air is inhibiting all but a few cells from
precipitating further east. While low (15-25%) rain chances
continue today in central Missouri, most of the region will enjoy
a dry Labor Day with very similar conditions to yesterday.
Temperatures will be further stunted in central Missouri where
cloud cover remains more abundant, but will be generally below-
normal areawide. The mid-level wave causing the showers is still
expected to slide south and east through the evening and settle
over the Ozarks on Tuesday. While temperatures will stay somewhat
suppressed (upper 70s to low 80s) during the day, rain chances
will be fairly low (20%) and confined to the Ozarks themselves.

MRB

&&

.LONG TERM...  (Tuesday Night through Sunday)
Issued at 245 AM CDT Mon Sep 1 2025

Most guidance is now suggesting a brief warmup on Wednesday ahead of
a strong cold front and impressive closed upper level low diving
south from central Canada. Warmer westerly winds and decreased cloud
cover will send temperatures back to near-normal ahead of the front,
roughly in the mid-80s for most of the area. Most solutions don`t
bring the front into the northern forecast area until around sunset.
Once here, confidence is increasing that showers will fill in along
the front and bring our best chance for more than a few hundredths
of an inch of rain in the next week. That said, convection will be
fairly weak, if it can occur at all with waining MUCAPE values in
most available guidance by the time the front arrives. NBM
probabilities of 0.50 inches of rain Wednesday night never tops more
than 15%, which doesn`t bode well for the gradually-worsening
drought.

While it`s not uncommon to see cold air lag behind the effective
cold front this time of year, that will certainly not be the case
Thursday morning. Much cooler and drier air will rush into the
region by Thursday, sending temperatures anywhere from 10-15 degrees
below Wednesday`s highs. The coolest conditions will be across
northern Missouri, where highs will struggle to warm to 70 degrees.
Elsewhere, upper 60s to low 70 are forecast and a stellar weekend is
on tap. The trend for a more persistent cooldown, at least through
the weekend, also continues with a reinforcing cold front diving
south Friday evening. This cooldown looks more likely to last
through the weekend, but those who are heralding this cooldown as
the "end of summer" may want to hold off on that rhetoric. The NBM
temperature envelope shows a persistent warming trend going into the
middle of next week, which matches the CPC Temperature Outlooks and
CIPS Extended Analog Guidance from Saint Louis University.

MRB

&&

.AVIATION...  (For the 06z TAFs through 06z Monday Night)
Issued at 1047 PM CDT Sun Aug 31 2025

Only minor changes were made to this iteration of the TAF. VFR
conditions remain most likely to prevail throughout the period.
There remains a very conditional chance for a few showers at
primarily COU/JEF in the mid to late afternoon, but it remains
somewhat unlikely that terminals will be directly impacted, and
that flight categories will be reduced either by reduced
visibility from rainfall or lowering ceilings. Otherwise, winds
will remain light and east-northeasterly.

BRC

&&

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

$$

WFO LSX