605
FXUS63 KLSX 311102
AFDLSX

Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
602 AM CDT Sun Aug 31 2025

.KEY MESSAGES...

- Low (15-35%) rain chances will persist through Tuesday, mainly
  in central Missouri, though most of the time will be dry.

- Scattered showers and perhaps a rumble of thunder are possible
  areawide along a potent cold front on Wednesday that will send
  Thursday`s highs well-below normal.


&&

.SHORT TERM...  (Through Late Monday Afternoon)
Issued at 312 AM CDT Sun Aug 31 2025

Subtle shortwave impulses amidst northwest upper-level flow are
evident on GOES East Mid-Level Water Vapor imagery, which is
interacting with a more moist airmass across the central Plains to
stimulate increased cloud cover and a few showers in western
Missouri. Across our forecast area, dry, easterly surface flow is
inhibiting any of this rain from reaching the ground. While a few
observation sites across the Ozarks reported intermittent rain
overnight, most of the region saw little to no rain. This trend
will generally continue through the day today across the western
two- thirds of Missouri, with mostly dry conditions and some
intermittent showers. One item of note is the rainfall at Columbia
- if little to no rain is observed, this will be the second-
driest August on record. The more notable impact from these mid-
level impulses will be the persistent cloud cover, which will
suppress temperatures from today onward. Highs today will be a few
degrees cooler than yesterday, particularly in central/northeast
Missouri, which starts the first of several abnormally-cool days.

Nearly-identical conditions will exist for Labor Day: mostly dry
conditions with temperatures ticking further below normal. By this
point, a more organized mid-level wave will amplify over northwest
Missouri and drift southwest into the Ozarks. This will gradually
shift the focus for showers south and east accordingly, but most of
the region will stay dry.

MRB

&&

.LONG TERM...  (Monday Night through Saturday)
Issued at 312 AM CDT Sun Aug 31 2025

The wave makes further progress southeast by Tuesday, shifting the
rain chances across the Ozarks more concretely, but the quality of
available moisture to this forcing is pretty poor. NAEFS depiction
of low-level moisture is a few standard deviations below normal,
which will keep shower coverage scattered at best and rain totals
fairly low in an area that is increasingly dry. Temperatures remain
seasonably cool with the abundant cloud cover on Tuesday, but will
make a rebound back to early-September normals for Wednesday as the
wave departs the region. The warmup doesn`t last long, as all
available guidance continues to show a very potent cold front and a
very anomalous upper-level trough dive south into the Mid-
Mississippi Valley Wednesday night. While scattered showers will
pepper the front as it passes, rainfall totals of any consequence
are very unlikely with the antecedent dry airmass in place. The
bigger story will be the much colder air (as much as 15 degrees
colder than Wednesday`s highs) by Thursday. While short-lived,
temperatures Thursday will struggle to warm more than the low 70s
for most, with those in northeast Missouri enjoying the coolest air.
While temperatures will gradually moderate into next weekend, dry
and seasonably-cool air will stay in place amidst persistent
northwest flow aloft.

MRB

&&

.AVIATION...  (For the 12z TAFs through 12z Monday Morning)
Issued at 602 AM CDT Sun Aug 31 2025

VFR conditions are expected to prevail through the TAF period across
the region. A few brief, intermittent showers may impact the central
Missouri terminals this morning, but categorical impacts are very
unlikely. Winds will remain generally out of the east through the
period, streaming in enough low-level dry air to keep CIGs largely
unimpactful.

MRB

&&

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

$$

WFO LSX