Old Jamestown, Missouri 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

462
FXUS63 KLSX 141754
AFDLSX

Area Forecast Discussion
National Weather Service St Louis MO
1154 AM CST Sat Nov 14 2026

.KEY MESSAGES...

- Quiet weather and below normal temperatures will continue
  today and Sunday. Temperatures will warm back to near normal
  Monday, and then above normal for the rest of the week.

&&

.SHORT TERM /THROUGH SUNDAY/...
Issued at 320 AM CST Sat Nov 14 2026

A high amplitude upper pattern remains locked in place over the
CONUS this morning.  The deep long wave trough over the eastern U.S.
will continue pulling a strong Canadian high pressure system south
into the Mississippi Valley today into tonight.  The sky  has
cleared out as the trough slowly drifts east and the upstream
ridge is also making slow progress into the Midwest. All
indications point toward a sunny Saturday, and after a chilly
start to the morning in the low to mid 20s, the NBM is
forecasting highs in the 45-50 degree range. This tracks closely
with conditional climatology which suggests a 20-25 degree rise
with light winds and full sunshine in November. Excellent
radiational cooling conditions under a clear sky and light winds
tonight will allow temperatures to drop into the low to mid 20s
again Sunday morning. Full sunshine is expected again on Sunday
as the center of the surface high drifts slowly across
Illinois. Should see highs a couple of degrees warmer on Sunday
afternoon as heights rise and the Canadian airmass modifies.

&&

.LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...
Issued at 320 AM CST Sat Nov 14 2026

Quiet and dry weather continues at least through midweek as the
upper level ridge builds over the Mississippi Valley and the
surface high drifts across the Ohio Valley and into the Mid Atlantic
Region.  Highs warm up to near seasonal normals in the mid 50s by
Monday, and then further into the upper 50s Tuesday, and then 60s on
Wednesday and Thursday as southerly flow increases ahead of the next
upstream short wave. Global guidance shows little moisture return
through at least Tuesday with ridging over the eastern 1/2 of the
CONUS blocking the Gulf, so the sky should remain clear to mostly
clear through that period. The clear sky and continuing light winds
overnight will allow temperatures to fall into the 20s again Monday
and Tuesday mornings in most locations.  However, increasing
southerly flow on the western side of the surface ridge will keep
temperatures from falling as much on Wednesday morning except in
sheltered locations.  Then there should be some moisture return into
the region Wednesday and Wednesday night as a short wave crosses the
Rockies and forces cyclogenesis over the Plains. Deterministic
guidance is in pretty good agreement up to that point in the
forecast, but begins diverging Thursday into Friday.  There`s
disagreement between the GFS and ECMWF on the amplitude and
orientation of the short wave as it moves from the Plains into the
Midwest Wednesday night into Thursday.  This leads to differences in
the strength of the surface low, how far southeast the associated
cold front travels, and how much moisture is pulled up into the Mid
Mississippi Valley ahead of it.  The GFS is largely dry for Thursday
and Friday, but the ECMWF is showing stronger moisture return and
prints out around 1/2 an inch of QPF. About 20-30 percent of the
LREF members have precip for our area which agrees well with the
latest NBM forecast.  Therefore chance PoPs for the end of the
forecast period continues to look reasonable, along with
temperatures warming well above normal in southwest flow ahead
of the front.

&&

.AVIATION /12Z TAFS THROUGH 18Z SUNDAY/...
Issued at 1058 AM CST Sat Nov 14 2026

High pressure continues to bring clear conditions and light winds
for the next couple of days. Morning fog will be possible in the
river valleys Sunday morning, and with temperatures well below
freezing it would be in the form of FZFG. This is most likely at JEF
and SUS, though could also impact CPS.

&&

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

&&

$$

SHORT TERM...Carney
LONG TERM...Carney
AVIATION...Jaja