Old Jamestown, Missouri 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

844
FXUS63 KLSX 060425
AFDLSX

Area Forecast Discussion
National Weather Service St Louis MO
1125 PM CDT Mon Oct 5 2026

.KEY MESSAGES...

- Dry weather and above normal temperatures are expected this
  week.

&&

.SHORT TERM /THROUGH TUESDAY NIGHT/...
Issued at 245 PM CDT Mon Oct 5 2026

Quiet weather continues through the short term with high pressure
moving east from the Upper Midwest through the Great Lakes. Cool
easterly flow will become light and variable tonight, and then turn
to the south and southwest on Tuesday. The light winds, clear skies,
and low dew point temperatures tonight will be ideal for radiational
cooling.  Therefore the 25-30 degree temperature drop to the mid 40s
to around 50 as advertised by guidance looks entirely reasonable.
Likewise the 30 degree warmup on Tuesday to the upper 70s to around
80 also looks good with full sunshine and southerly flow.

&&

.LONG TERM /WEDNESDAY THROUGH MONDAY/...
Issued at 245 PM CDT Mon Oct 5 2026

The remainder of the forecast looks relatively quiet as well.  A
broad upper level trough remains over the eastern U.S. with a ridge
over the west.  A dry surface ridge axis is forecast to remain south
of the Mid Mississippi Valley through the end of the week, and this
will keep deep moisture return to a minimum.  Deterministic guidance
shows a short wave trough moving through the Upper Midwest
Wednesday.  The wave briefly amplifies the broader trough to our east
and pushes a cold front through Missouri and Illinois Wednesday
night into Thursday.  Forecast soundings show little moisture for
the front to interact with, so it`s very likely there will be no
precipitation associated with it at least through Thursday.
Temperatures on Wednesday will likely be the warmest of the work-week
in the mid to upper 80s due to the warmer start to the morning and
west-southwest flow ahead of the front.  There may be some showers
late Thursday night into Friday morning, mainly over northeast
Missouri in low level warm advection as the front lifts back to the
north of the area. Only 15 percent of the LREF members have any
precip though, so the slight chance PoPs in far northeast
Missouri that the NBM is showing look good.

The overall pattern shifts eastward next weekend with the upper
ridge moving through the Plains into the Mississippi Valley.
The latest deterministic GFS brings a tropical system ashore
from the Gulf near the mouth of the Mississippi River early
Saturday morning which could complicate the forecast for the
weekend. The ECMWF also shows a tropical system moving from the
Gulf into the southern CONUS this weekend, but it`s far slower
and weaker than the GFS`s solution. The LREF mean agrees more
with the ECMWF solution at this point, so the drier and warmer
forecast in the NBM looks more likely than the GFS. However, the
LREF cluster analysis shows some pretty significant differences
in the position of the upper ridge. The position of the ridge
would likely affect the strength of any landfalling tropical
system, as well as the course it ultimately follows. A shift in
the position of the ridge and the upstream trough could bring
the tropical system up the Mississippi Valley into Missouri and
Illinois on Saturday which would produce much cooler and more
rainy conditions than are currently forecast. Therefore my
confidence in the weekend forecast is low at this time.

&&

.AVIATION /06Z TAFS THROUGH 12Z WEDNESDAY/...
Issued at 1125 PM CDT Mon Oct 5 2026

Dry and VFR flight conditions are likely through the TAF period.
Although patchy river valley fog is possible again overnight/Tuesday
morning, the wind direction is less favorable for river valley
terminals to be impacted. Winds will become more southerly to
southwesterly during the day Tuesday but will still be generally
light.

&&

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

&&

$$

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