Old Jamestown, Missouri 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

855
FXUS63 KLSX 120322
AFDLSX

Area Forecast Discussion
National Weather Service St Louis MO
1022 PM CDT Sat Jul 11 2026

.KEY MESSAGES...

- Localized downpours could lead to pockets of flash flooding
  through the remainder of the afternoon. A Flash Flood Watch
  remains in effect south of the I-70 corridor through 7pm CDT.

- A Marginal Risk (level 1 of 5) for severe weather exists along
  and southeast of a Taylorville, Illinois to Cuba, Missouri
  line through this evening. The primary hazard will be
  scattered damaging wind gusts.

- Typical summertime heat and humidity will prevail for the
  week ahead.

&&

.SHORT TERM /THROUGH SUNDAY/...
Issued at 239 PM CDT Sat Jul 11 2026

An upper-level low evident on 19z/2pm water vapor imagery over
southwest Illinois continues to pivot slowly southeastward this
afternoon. Scattered showers and thunderstorms accompany the
wave...particularly along/south of a Springfield, Illinois to
Columbia, Missouri line. SPC mesoanalysis shows precipitable
water values of 1.80-2.10 across the E/SE LSX CWA. Given copious
atmospheric moisture and the very slow movement of the cells
currently developing, think the primary hazard for the remainder
of the afternoon into early this evening will be scattered
downpours with rainfall rates up to 2 inches per hour. Not all
locations will receive rain, but there is a potential that a
few spots could experience localized flash flooding, especially
south of the I-70 corridor where the Flood Watch will remain in
effect until 7pm.

Will also need to keep an eye on the potential for isolated
severe weather. While 0-6km bulk shear remains paltry at less
than 30kt, modest MLCAPEs of 1000-1500J/kg and 0-3km lapse rates
of around 7C/km may be enough to support gusty winds with some
of the stronger cells as the afternoon progresses. In addition,
with Non-Supercell Tornado Parameter values of 1-2 directly
beneath the upper low, a few funnel clouds may be observed with
the developing showers...mainly from the Saint Louis area
eastward into Illinois.

Once the low drops south of the Ohio River, rain chances will
come to an end from northwest to southeast across the area early
this evening...followed by mostly clear and dry conditions
tonight into Sunday. Lows tonight will be in the middle to upper
60s and highs on Sunday will top out in the middle 80s.

&&

.LONG TERM /SUNDAY NIGHT THROUGH SATURDAY/...
Issued at 239 PM CDT Sat Jul 11 2026

A Rex Block is progged to develop this week as a prominent
596dm 500mb high currently over the Desert Southwest lifts
northeastward and strengthens over the Central Plains into the
western Great Lakes and troughing prevails from the Southern
Plains across the Deep South. This will lead to warmer/drier
weather for the region. Low chance PoPs (20-30%) will primarily
be confined to the southern CWA south of the Saint Louis metro
during the afternoons from Tuesday through Thursday while temps
slowly climb each day. Highs on Monday/Tuesday will top out in
the upper 80s to around 90 degrees, then will rise into the
lower to middle 90s Thursday through Saturday. Corresponding
heat index values will rise above 100 degrees as the week
progresses.

&&

.AVIATION /00Z TAFS THROUGH 06Z MONDAY/...
Issued at 1017 PM CDT Sat Jul 11 2026

Mainly dry conditions are expected through the period. Other
than some fog with MVFR visibilities late tonight into early
tomorrow in the river valleys affecting JEF, SUS, and CPS
between 09-13Z, mainly VFR conditions are expected. Winds are
expect to remain below 10 knots.

&&

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

&&

$$

SHORT TERM...WFO ILX
LONG TERM...WFO ILX
AVIATION...Britt