Old Jamestown, Missouri 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

412
FXUS63 KLSX 070722
AFDLSX

Area Forecast Discussion
National Weather Service St Louis MO
222 AM CDT Wed Oct 7 2026

.KEY MESSAGES...

- No precipitation and above average temperatures are forecast
  through the week.

- It is uncertain if the remnants of developing Tropical
  Depression Nine will bring any precipitation and cooler
  temperatures to our area late Saturday through Sunday.

&&

.SHORT TERM /THROUGH FRIDAY/...
Issued at 217 AM CDT Wed Oct 7 2026

With a tightening surface pressure gradient, temperatures early this
morning are warmer than Tuesday morning and mainly in the 50s to
around 60 F, with the exception of some 40s F in sheltered locations
across east-central/southeastern MO and southwestern IL closer to
weakening surface high pressure. This tightening pressure gradient
is in response to an approaching cold front that will advance
southeastward through the area today. With full insolation,
seasonably deep boundary-layer mixing, favorable pre-frontal low-
level west-southwesterly flow/WAA, and even some downsloping off the
Ozark Plateau; temperatures will warm to well-above average today,
in the 80s F. Moisture and forcing is anticipated to be insufficient
for precipitation with the front. In fact, there may not even be
much in the way of clouds with the front.

The front is progged to clear the CWA sometime tonight with
weak/short-lived low-level dry air and CAA and an arriving surface
high pressure potentially permitting enough radiational cooling for
fog formation in river valleys overnight into Thursday morning,
especially across the Ozarks. With limited CAA, temperatures will be
only slightly cooler and still above average on Thursday.

The front will lift back northward Thursday night into Friday
morning in response to surface cyclogenesis across the Northern High
Plains and/or Alberta. Ensemble model guidance continues to
highlight the most favorable area for any WAA-driven precipitation
associated with the warm front and a LLJ to be focused across the
Central Plains and Upper Midwest with the majority of membership
keeping the CWA dry. In the warm sector enveloping the CWA behind
the warm front and beneath an amplifying upper-level ridge, well-
above average temperatures will return with NBM distribution
indicating high temperatures in the 80s to around 90 F, approaching
daily records.

&&

.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
Issued at 217 AM CDT Wed Oct 7 2026

Global model guidance remains in agreement that the large-scale
upper-level wave pattern across North America will amplify over the
weekend as the aforementioned amplifying ridge migrates eastward and
a trough deepens over the West Coast. Most of the forecast interest
and uncertainty, however, is focused on the evolution of Tropical
Depression Nine, currently in the southwestern Gulf of Mexico. This
tropical cyclone will likely continue strengthening into a hurricane
and make landfall somewhere along the northern Gulf Coast as it is
steered northward between the West Coast trough and a subtropical
upper-level ridge/high across the eastern Atlantic Ocean as well as
interaction with an upper-level low initially over the Southern
Plains. After landfall, most ensemble and deterministic global and
tropical-cyclone models track the weakening tropical cyclone to the
south and southeast of the Mid-Mississippi River Valley late
Saturday through Sunday with just some increasing upper-level
clouds, but the northwestward-most members have tracks into
southeastern MO and southern IL which would include showers and more
abundant cloud cover reaching the CWA. The track and timing of this
tropical system is very uncertain and it may not be until much much
closer to that time that resolution improves more considerably.
Although there is strong support for continued above average
temperatures through the weekend into early next week, the NBM
interquartile range expands to around 6 to 8 F since it is not clear
if temperatures will be cooled by clouds and precipitation.

&&

.AVIATION /00Z TAFS THROUGH 06Z THURSDAY/...
Issued at 1134 PM CDT Tue Oct 6 2026

Aside from the potential for river fog valley impacting KSUS
Wednesday morning, dry and VFR flight conditions are expected
despite a cold front advancing southward through the area between
late morning and evening. The only impact of this front will be
veering winds from westerly to northwesterly and then northerly or
variable during the evening.

&&

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

&&

$$

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