Old Jamestown, Missouri 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

955
FXUS63 KLSX 211707
AFDLSX

Area Forecast Discussion
National Weather Service St Louis MO
1207 PM CDT Wed Oct 21 2026

.KEY MESSAGES...

- Seasonably warm and dry weather will last through this weekend.

&&

.SHORT TERM /THROUGH THURSDAY/...
Issued at 257 AM CDT Wed Oct 21 2026

No significant changes have been made to the forecast. The mid-level
omega blocking pattern and surface high pressure influence will keep
our sensible weather consistently dry, and insolation will act as
the sole driver for our gradually warming temperatures. Expect highs
generally in the mid-70s today and tomorrow with lows in the 40s to
low-50s in between.

&&

.LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/...
Issued at 257 AM CDT Wed Oct 21 2026

The pattern begins to change late this week. A mid-level longwave
trough circling over the Four Corners area is expected to split,
with its poleward section phasing into another trough traversing
western Canada. This shift will pull a cold front into the Upper
Midwest Saturday and orient it zonally on Sunday as the shortwave
zips into eastern Canada. The Mid-Mississippi Valley will remain
well south of the cold front over the weekend, and our temperature
trends will reflect that. LREF probabilities of 1pm temperatures >69
degrees Saturday and Sunday both range from 75-100%, and the NBM max
temperature spread for each day is only 3 degrees. The cold front is
expected to finally push into the region on Tuesday, but cooler
weather is not guaranteed especially for locations south of I-70.
Guidance suggests that the front may be weakening as it arrives, and
that it may become stationary before it clears the area. This would
mean that less cool air would filter into less of the CWA and that
the warm streak may continue through Tuesday. Confidence in this, or
for any solution, is still very low given the timeframe in question.
Again, the NBM max temperature spread reflects this well as it
climbs to 10+ degrees on Tuesday and nearly 20 degrees on
Wednesday.

&&

.AVIATION /12Z TAFS THROUGH 18Z THURSDAY/...
Issued at 1157 AM CDT Wed Oct 21 2026

Surface high pressure is located across eastern OH/ western PA
with mid clouds approaching the region from the west. VFR
conditions are forecast to persist through the afternoon into
the evening. Another upper level wave will move across southern
Canada, helping to retrograde the surface ridge axis back to
the northwest late this evening. Winds at the TAF sites will
slowly back from the northeast before decoupling. Thursday
morning, another round of morning river valley fog appears
likely as winds go calm. The greatest threat for restrictions
in visibilities will be at KSUS, while slightly lower chances at
KJEF and KCPS. As the sun rises, mixing will quickly commence
bringing an end to the river valley fog. VFR Thursday with no
precipitation expected.

&&

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

&&

$$

SHORT TERM...Jaja
LONG TERM...Jaja
AVIATION...BAH/ Giordano