Old Jamestown, Missouri 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

614
FXUS63 KLSX 110955
AFDLSX

Area Forecast Discussion
National Weather Service St Louis MO
355 AM CST Wed Nov 11 2026

.KEY MESSAGES...

- Occasional wind gusts of 25 to 35 mph will follow the passage
  of a cold front today with the coldest temperatures so far
  this season arriving by Friday.

- Aside from isolated to scattered light showers on Thursday,
  largely dry conditions will persist.

&&

.SHORT TERM /THROUGH SATURDAY NIGHT/...
Issued at 159 AM CST Wed Nov 11 2026

An upper-level shortwave trough, evident in early morning water
vapor imagery across the Central Plains, will propagate east-
southeastward today, driving a cold front through the CWA after
sunrise into early afternoon as it trails a deepening surface
cyclone passing to the north. Model guidance still points to this
cold front making a dry passage with moisture and instability not
sufficiently increasing for scattered shower and thunderstorm
development until the front is east of the CWA. With the strongest
CAA lagging behind the front, deep boundary-layer mixing, and strong
insolation; high temperatures will again be above average and in the
60s to low-70s F, beginning to fall during the late afternoon. A
tight surface pressure gradient will also support occasional 25 to
35 mph wind gusts during the afternoon and evening as CAA
strengthens.

Behind the initial shortwave trough, deep northwesterly flow will
become established as another shortwave trough arrives on Thursday.
Broad ascent, lingering moisture, and CAA-steepened lapse rates will
be favorable for isolated to scattered sprinkles and light showers,
especially during the late morning into afternoon along/east of the
Mississippi River as a secondary cold front passes. CAA and
extensive stratocumulus in addition to this periodic precipitation
will only allow high temperatures to reach the 40s to low-50s F on
Thursday. Some sprinkles could linger across south-
central/southwestern IL Thursday night, perhaps even a wet snow
flurry late as temperatures cool into the 30s F and the 0C wet-bulb
height lowers.

CAA will continue into Friday as the core of the seasonably cool
airmass arrives, accompanied by the coldest temperatures the CWA has
seen so far this season including highs in the 40s and lows in the
20s F. Confidence is highest in the coldest temperatures being
Saturday morning with mostly clear skies and a surface anticyclone
positioned nearby, but clouds may increase late Saturday
night/Sunday morning which could impact the efficiency of
radiational cooling, especially west of the Mississippi River.

&&

.LONG TERM /SUNDAY THROUGH TUESDAY/...
Issued at 159 AM CST Wed Nov 11 2026

By Sunday, longwave troughing is anticipated to begin departing the
eastern CONUS with cyclonic flow weakening over the Mid-Mississippi
River Valley as heights rise. Global model guidance is coming into
much better agreement that this process and the retreat of the
surface anticyclone will be slow, with NBM temperatures tightly
clustered only a very gradual moderation in temperatures toward
average through early next week. At the same time, there remains a
signal for an upper-level trough to track from the Central Plains to
the Mid/Lower Mississippi River Valley Sunday into Monday. This
feature will likely at least provide increased clouds that help slow
the aforementioned warming trend, but global ensemble model
probabilities of any measurable rainfall only reach 20 to 30 percent
across central and southeastern MO with the highest probabilities
across KS, OK, and AR. Therefore, the prospects of rainfall are
questionable at this point.

&&

.AVIATION /06Z TAFS THROUGH 12Z THURSDAY/...
Issued at 355 AM CST Wed Nov 11 2026

Most of the patchy river valley fog will dissipate before 12z this
morning as winds begin to increase ahead of an approaching cold
front. This cold front will advance eastward through the area this
morning into early afternoon with winds veering from southwesterly
to northwesterly and strengthening with occasional gusts of 25 to 35
mph continuing into the evening. However, precipitation is unlikely
with this front and flight conditions are anticipated to remain VFR
with only low-VFR stratocumulus increasing tonight. Northwesterly
winds will slacken some after sunset with most gusts subsiding.

&&

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

&&

$$

SHORT TERM...Pfahler
LONG TERM...Pfahler
AVIATION...Pfahler