Old Jamestown, Missouri 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

478
FXUS63 KLSX 050815
AFDLSX

Area Forecast Discussion
National Weather Service St Louis MO
315 AM CDT Mon Oct 5 2026

.KEY MESSAGES...

- Largely dry conditions persist through the work week, with
  temperatures remaining 5 to 10 degrees above average, and
  little in the way of weather hazards expected.

&&

.SHORT TERM /THROUGH TUESDAY NIGHT/...
Issued at 313 AM CDT Mon Oct 5 2026

Rather uneventful weather conditions can be expected for the next
few days (and longer), thanks to persistent high pressure and a dry,
continental airmass. As expected, a weak cold front moved through
the area yesterday, and while it didn`t meaningfully impact
temperatures then, we should see a drop of a few degrees from the
previous day thanks to modest "cold" air advection. This will be
barely noticeable though, as we still expect temperatures to
generally range from the low to upper 70s throughout the area.
Meanwhile, winds will remain light and variable, and minimal cloud
cover can be expected.

After another chilly night with very light winds and clear skies,
along with a few patches of shallow ground fog in a few river
valleys, surface pressure falls across the Central Plains should
drive a modest increase in southwesterly surface winds during the
day Tuesday. While the impact of this will be subtle, the effect of
downsloping winds off the Ozarks is expected to raise temperatures
back to near 80 degrees in most areas, while also lowering humidity
levels to near 30%. While we don`t expect winds to be strong enough
to produce a significant fire threat, some areas with abundant dead
fine fuels (i.e. cured grass) may see a slight uptick in fire
behavior Tuesday afternoon as a result. Otherwise though, expect
another warm, sunny fall day area-wide.

&&

.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
Issued at 313 AM CDT Mon Oct 5 2026

For the rest of the week, the bulk of the forecast remains centered
on subtle differences in temperatures from day to day, although
confidence remains high that we will remain at least slightly above
average through the end of the week. As mentioned in previous
forecasts, the upper flow pattern will be characterized by a broad,
stagnant ridge across the western CONUS, with northwesterly to quasi-
zonal flow overhead for at least the first half of the week. At some
point this upper ridge is expected to drift eastward into the
Mississippi River Valley and eventually the eastern CONUS,
although confidence in this evolution decreases considerably
over the weekend.

While surface high pressure and a dry airmass will continue to be
the driver of sensible weather through the end of the workweek,
there are some subtle developments that may cause some minor changes
from day to day. The first of these features is a weak cold front
that is expected to approach the area sometime late
Wednesday/Thursday, and ensemble guidance has steadily increased its
influence on forecast temperatures over the past couple of days.
It`s still only a matter of a few degrees, but this front may slow
our warming trend Wednesday-Friday, especially north of I-70. Not
only this, but we also note some modest moisture pooling showing up
along this front, and a smattering of light QPF and/or cloud cover
along this boundary...most notably Friday as it lifts back north as
a warm front. Still, moisture levels remain very low, and we have
very little confidence that this will yield any meaningful
rainfall. Instead, we will maintain the going forecast for
temperatures roughly 5-10 degrees above average through the work
week, with warmest readings across the Ozarks and southwest IL.


As mentioned previously, over the weekend is when the synoptic
pattern is set to change more substantially, although exactly how
quickly this occurs will determine the day-to-day specifics. The
potential exists for temperatures to warm slightly as the upper
ridge moves overhead and southerly low level flow resumes, and there
are also hints that this could bring some increasing humidity back
to the north...and potentially even some precipitation. Temperature
spreads remain high late in the forecast period, and there is little
consistency among members when it comes to precipitation timing or
locations, but there is at least some hope that this pattern change
will at least open the door for it.

&&

.AVIATION /06Z TAFS THROUGH 12Z TUESDAY/...
Issued at 1026 PM CDT Sun Oct 4 2026

VFR conditions will persist at most terminals with exception to
KSUS and KCPS, where steam fog could impact each site in the
early morning (09z-12z). TEMPO groups were added for a brief
period of MVFR visibility, but is expected dissipate quickly
after sunrise.

&&

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

&&

$$

SHORT TERM...19
LONG TERM...19
AVIATION...Maples