Old Jamestown, Missouri 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

786
FXUS63 KLSX 120804
AFDLSX

Area Forecast Discussion
National Weather Service St Louis MO
304 AM CDT Sat Sep 12 2026

.KEY MESSAGES...

- There is a chance (20-30%) for showers and thunderstorms
  across central and northeast Missouri into west central
  Illinois late this afternoon and tonight. The chance for rain
  spreads southeast across the area on Sunday.

- Temperatures will remain above normal for most of the area
  into next week with a chance for rain continuing, mainly
  across northern Missouri into central Illinois.


&&

.SHORT TERM /THROUGH SUNDAY/...
Issued at 302 AM CDT Sat Sep 12 2026

Latest surface observations are showing a few locations reporting
fog, though not nearly to the extent of what we saw yesterday
morning.  Winds are light and dewpoint depressions are close to zero
across the area, so I would expect some additional fog development
in the next few hours, particularly in river valleys.

The latest surface analysis shows a cold front extending from
Minnesota into Nebraska which RAP/NAM brings into the northwest
CWA this afternoon. I only expect just a slight chance (20%) of
showers and thunderstorms confined to northeast and central
Missouri and west central Illinois late this afternoon and this
evening along the front as forecast soundings are capped ahead
of the front. Latest guidance from the CAMS suggests that the
greatest chance for storms overnight tonight will stay to the
west of the CWA where the greatest instability will be along the
front, though will still keep a low chance (20-30%) going
across central and southeast Missouri. I have 20-40% chance of
showers and thunderstorms going across the entire area on Sunday
as the front will continues to move south across the southern
CWA and the NAM/GFS are showing a weak shortwave trough moving
across Missouri and Illinois providing some weak lift.

Highs today ahead of the front will climb in the middle 80s to
around 90 degrees with light southwest winds and sufficient
insolation. There will be quite contrast in temperatures on Sunday
with the front in the area with highs only in the mid 70s over
northeast Missouri to around 90 degrees over the southern CWA.

&&

.LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...
Issued at 302 AM CDT Sat Sep 12 2026

The LREF has an upper high building across the southern CONUS early
next week which will brings the front back north across the CWA on
Monday keeping a chance of showers and thunderstorms across the
area.  This will also puts us into southwest flow aloft Tuesday and
Wednesday which will keeps a cold front stalled across northern
parts of Missouri and Illinois. The 850mb temperatures are
forecast to climb back to around 20C with southwesterly surface
winds behind the warm front supporting highs back into the 80s
and 90s. This is supported by the NBM IQR at St. Louis which has
highs in the mid 90s on Tuesday and Wednesday with a spread of
only 3 degrees. This spread increases late next week as the
upper high retrogrades which will allow the upper flow to become
zonal which brings into question where the surface front will
be Thursday into Friday. 30-60% of the LREF members are
producing rain over the CWA Thursday into Friday. Temperatures
will also begin to drop off closer to normal with the front and
rain chances.

&&

.AVIATION /00Z TAFS THROUGH 06Z SUNDAY/...
Issued at 1037 PM CDT Fri Sep 11 2026

VFR conditions with calm to light winds will continue for the
TAF period. A possibility for fog exists for JEF, SUS, and CPS
during the early morning hours that could create brief periods
of IFR, but the chances are low compared to yesterday due to
warmer and dryer surface conditions. Winds will initially be out
of the south, but as a cold front moves through the region on
Saturday the winds are expected to shift northwesterly.

&&

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

&&

$$

SHORT TERM...Britt
LONG TERM...Britt
AVIATION...Asel/Kimble