Old Jamestown, Missouri 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

519
FXUS63 KLSX 110831
AFDLSX

Area Forecast Discussion
National Weather Service Saint Louis MO
331 AM CDT Mon Aug 11 2025

.KEY MESSAGES...

- Seasonably warm and humid weather will continue this week with
  highs near normal in the mid 80s to around 90 in most locations.
  There will be a chance for thunderstorms, primarily in the
  afternoon and evening at least through Wednesday or Thursday.

- Temperatures are expected to warm above normal by the end of the
  week in to the weekend.

&&

.SHORT TERM...  (Through Late Tonight)
Issued at 328 AM CDT Mon Aug 11 2025

A mid/upper level trough remains over the Great Plains today. The
surface front is difficult to find in surface obs due to ongoing
convection and old outflows.  The low level forcing for convection
will therefore weak and diffuse today, and will remain so through
tonight.  This will make the timing and location of convection
difficult to forecast through the period.  Regardless, the GFS and
RAP show up to 2000-2500 J/Kg MLCAPE building up across Missouri
into Illinois this afternoon, and both models produce precip during
the late afternoon and evening. Most CAMs also develop thunderstorms
during the mid to late afternoon, and some have convection
persisting through much of the night. Therefore I feel that some
level of chance PoPs are warranted through the period, though I`m
not confident enough to go higher than 50% in any given location or
time frame.

Carney

&&

.LONG TERM...  (Tuesday through Sunday)
Issued at 328 AM CDT Mon Aug 11 2025

The Great Plains trough finally starts moving east late tonight and
Tuesday.  The associated cold front will drift into Missouri and
Illinois Tuesday morning providing some low level forcing for
additional thunderstorm development.  RAP/GFS both develop precip
ahead of the front, though it doesn`t look particularly organized.
Both models develop around 2500 J/Kg MLCAPE during the afternoon but
the deep layer shear remains weak at 20kts or less.  Additionally,
there`s some weak CINH during the afternoon and convergence along
the front is not very strong.  Latest CAMs only show
scattered/disorganized convection Tuesday afternoon.  Will therefore
increase PoPs in the chance range through Tuesday afternoon.
Instability falls off quickly in the evening and CINH increases so
convection should weaken rapidly during the evening.

Upper level ridging builds across the Plains and Midwest through the
remainder of the week.  Typical summertime temperatures in the mid
80s to around 90 are expected with a 20-30 percent chance for
afternoon and evening thunderstorms, mainly along and south of I-70.
The ridge continues to build overhead next weekend causing
temperatures to rise back above normal in the low to mid 90s.

Carney

&&

.AVIATION...  (For the 06z TAFs through 06z Monday Night)
Issued at 1031 PM CDT Sun Aug 10 2025

VFR conditions dominate the next 24 hours with a light southeast
wind. The main forecast concern is the potential for thunderstorms
which exists mainly from central Missouri potentially up toward
Quincy during the early morning hours.

Kimble

&&

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

$$

WFO LSX