Old Jamestown, Missouri 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

191
FXUS63 KLSX 190748
AFDLSX

Area Forecast Discussion
National Weather Service St Louis MO
248 AM CDT Mon Oct 19 2026

.KEY MESSAGES...

- Hazardous weather is not expected through the week as
  conditions remain dry and daily temperatures gradually warm.

&&

.SHORT TERM /THROUGH TUESDAY NIGHT/...
Issued at 240 AM CDT Mon Oct 19 2026

A broad, low-amplitude ridge encompasses much of the CONUS in the
upper levels this morning, with flow over the Middle Mississippi
Valley weakly quasi-zonal. The surface high responsible for our
local weather the last couple of days remains centered over the
Northeast, with surface flow over the CWA and along its southwestern
periphery being south-southeasterly. This will keep our temperatures
seasonable today, with values this afternoon (around 70 degrees)
about 5 degrees warmer than yesterday thanks mainly to a relatively
warmer start this morning. This forecast has been nudged down from
the 01z NBM solution, and even then it may still be too warm, as
weak disturbances traversing the flow aloft send waves of high
clouds over the CWA through the day.

The slightly warmer temperatures today and continuing scattered
cloud cover into the overnight hours will keep temperatures tonight
from getting as cool as they were the night prior, setting the stage
for a couple-degree bump in temperatures Tuesday afternoon compared
to those on Monday. This will be further supported by less cloud
cover allowing for more insolation.

&&

.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
Issued at 240 AM CDT Mon Oct 19 2026

At the start of the long-range forecast, guidance consensus is that
the axis of the upper-level ridge responsible for our early-week
warmup will have retrograded westward to be centered over the Great
Plains. This will place the CWA beneath northwesterly flow aloft,
and hold in place an area of surface high pressure over the
Northeast. The northwesterly flow aloft will keep low to mid-level
temperatures over the CWA steady through at least Thursday-Friday,
with the positioning of the surface high having winds weakly south-
southeasterly. Neither factors favor the warming temperatures
reflected in the NBM through this portion of the period, and an in-
depth analysis of this guidance shows that it is being pulled warm
by the usually warm-biased GFS/GEFS and bias-corrected guidance that
is being trained on our anomalous warmth of the last couple of
months. Mid-level clouds associated with subtle disturbances
cresting the ridge Wednesday into Thursday may help to further bring
afternoon temperatures down from their current forecast. Despite all
of this, the NBM is still within the range of reasonable outcomes
(albeit on the far warm side), and targeted changes will be made
with decreasing lead time as ensemble spread narrows.

As we get into the weekend, both deterministic models and ensemble
clusters show the upper-level ridge amplifying as it`s pushed by a
trough ejecting into the central CONUS. Despite this consensus, the
phasing of the trough and ridge among guidance Friday-Sunday varies
dramatically from model to model, leading to very low confidence in
our local weather through the weekend. Despite the variety of
solutions, nearly all global ensemble members and deterministic
models have the main thrust of the trough and associated shortwaves
moving north of the CWA. This supports a lack of notable FROPA and
temperatures holding steady through the weekend compared to the
middle and end of the week.

&&

.AVIATION /00Z TAFS THROUGH 06Z TUESDAY/...
Issued at 1041 PM CDT Sun Oct 18 2026

Light winds continue through Monday under a clear sky. There is
some potential for morning fog in the valley locations, though
confidence in this is too low to include in the TAF.

&&

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

&&

$$

SHORT TERM...Elmore
LONG TERM...Elmore
AVIATION...Kimble