711
FXUS63 KLSX 021051
AFDLSX

Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
551 AM CDT Sat Aug 2 2025

.KEY MESSAGES...

- Cool temperatures by summer standards and dry conditions are
  expected through the weekend.

- Temperatures will gradually warm through the workweek, with
  typical summer heat returning by the end of the week.


&&

.SHORT TERM... (Through Sunday Night)
Issued at 230 AM CDT Sat Aug 2 2025

Weak northwesterly flow is persisting over the Middle Mississippi
Valley per water vapor imagery this morning. Subtle shortwaves are
rounding the peak of an upper-level ridge centered over the
Intermountain West, spurring convection across the Great Plains.
Through the day, periods of convective blow off will impede upon the
CWA, mixed with a thin layer of wildfire smoke. With high pressure
lingering across the Midwest, pockets of smoke may mix down at times
through the day, but confidence is currently high that it will not
do so to the extent that was experienced on Friday.

Even with the pattern today being similar to yesterday, the surface
high will edge further into the region today, which will help keep
temperatures a degree or two cooler this afternoon. Little change in
the pattern is expected tomorrow, leading to very similar conditions
forecast as today.

Elmore

&&

.LONG TERM... (Monday through Friday)
Issued at 230 AM CDT Sat Aug 2 2025

At the start of the workweek, northwesterly flow is expected over
the Middle Mississippi Valley per guidance consensus. This will be
occurring on the northeastern periphery of an amplifying ridge and a
weak trough digging into the Ohio Valley and Southeast. A weak
shortwave rounding the base of this trough will slowly drift into
the Ohio Valley late Monday into Tuesday, pulling moisture poleward.
The deepest moisture in respect to the CWA will be over southeastern
Missouri and southwestern Illinois, where a low chance (20-30%) for
isolated to scattered showers and thunderstorms is forecast during
the afternoon Monday and Tuesday. Even though most locations will
stay dry during this two-day period, confidence is currently high
that this will be the most meaningful chance for rainfall during the
forecast period.

Through the workweek, the aforementioned ridge will slowly expand
eastward into the region. This will push the surface high
responsible for our relatively nice weather through the weekend
eastward and return low to mid-level southerly flow to the region.
Both temperatures and moisture will gradually increase through the
workweek in response, with ensemble means reaching 90 degrees for
much of the CWA by Thursday and Friday. If the ridge is able to
build into the region further as a minority of global ensemble
members suggest, afternoon highs would reach the low, maybe even mid-
90s, which would threaten a return of 100+ degree heat index
values.

Elmore

&&

.AVIATION...  (For the 12z TAFs through 12z Sunday Morning)
Issued at 533 AM CDT Sat Aug 2 2025

Lingering wildfire smoke is causing sporadic visibility reductions
this morning, with confidence low in brief impacts to visibility
at any of the local terminals through the day. Otherwise, light
northeasterly winds and VFR flight conditions are expected through
the period.

Elmore

&&

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

$$

WFO LSX