Old Jamestown, Missouri 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

559
FXUS63 KLSX 061929
AFDLSX

Area Forecast Discussion
National Weather Service St Louis MO
229 PM CDT Tue Oct 6 2026

.KEY MESSAGES...

- No precipitation and above average temperatures are forecast
  through the week.

&&

.SHORT TERM /THROUGH WEDNESDAY/...
Issued at 216 PM CDT Tue Oct 6 2026

Today and tonight: Surface high pressure is currently located near
the OH/ PA border this afternoon with the ridge axis extending to
the southwest. The entire states of MO and IL are cloud free as
PWATs are around 0.50" (or near the 10th percentile for this time of
year). Highs in the upper 70s are forecast. Surface high
pressure will move towards the Mid-Atlantic United States
tonight into early Wednesday morning with the ridge axis still
extending to the southwest across southeastern Missouri (likely
due to a weak upper level trough holding back to the west).
Given this, low temperatures in the upper 40s to lower 50s are
forecast for most of the area (upper 50s for STL).

Wednesday: Another mid-level wave will dive southeast out of central
Canada with a cold front trailing to the southwest. By Wednesday
afternoon, the cold front will be near the IA/ MO border with 850 mb
temperatures rising to around 17 degrees C. This coupled with
downslope (west/ southwest) flow off of the Ozarks will push
high temperatures in the mid to upper 80s across most of the
area (except far northern MO). No precipitation is forecast with
the cold front as even cloud cover will be sparse.


&&

.LONG TERM /WEDNESDAY NIGHT THROUGH TUESDAY/...
Issued at 216 PM CDT Tue Oct 6 2026

Thursday: The surface cold front from Wednesday will clear the CWA
with lower dewpoint air filtering in from the north. The core of the
cooler 850 mb temperatures will be confined to IL and IN though,
which means highs will be cooler generally north of I-70, while
south of I-70 expect high temperatures in the mid to upper 80s.

Friday and Saturday: Surface high pressure will quickly move east
towards the Mid-Atlantic states with widespread southerly flow
establishing itself across the area. In the upper level of the
atmosphere, the southern stream jet will begin to amplify with a
closed upper level low over Texas. Simultaneously, Invest-92L in the
eastern Gulf of Mexico (near 100 percent chance of development) will
be steered northward towards the eastern flank of the upper level
low. This is where uncertainty in the forecast rapidly increases.
Some guidance shows 92L moving north towards MO, while other
guidance has 92L moving north and then northeast. The other source
of uncertainty is a potent shortwave diving southeast near British
Columbia and a tropical system in the eastern Pacific (as supported
by the WPC Ensemble Sensitivity Analysis). This causes the IQR in
temperatures for St. Louis to be 15 to 20 degrees by Sunday and
Monday. As such, wide ranging differences in the deterministic
GFS/ ECMWF for Sunday and Monday can be expected over the next
couple of days (and resultant EPS/ GEPS/ and GEFS). The ESA
indicates that the sensitivity starts on Friday, meaning
potentially not until Friday will guidance come into better
agreement.

&&

.AVIATION /12Z TAFS THROUGH 18Z WEDNESDAY/...
Issued at 1200 PM CDT Tue Oct 6 2026

Today: All TAF sites are VFR this afternoon with winds
generally out of the south. Surface high pressure is currently
located over the OH/ PA border and is forecast to slowly move
east. As this occurs, winds will veer around from the
southwest. High pressure (and the resultant ridge axis) will
likely still be close enough to allow winds to go calm in the
river valleys while not going completely calm at KUIN, KCOU, and
KSTL. There will also be another round of river valley fog
possible at KSUS.

Wednesday: A cold front will approach the TAF sites from the
northwest with winds turning from the southwest. VFR.

&&

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

&&

$$

SHORT TERM...BAH
LONG TERM...BAH
AVIATION...BAH