Old Jamestown, Missouri 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

880
FXUS63 KLSX 031655
AFDLSX

Area Forecast Discussion
National Weather Service St Louis MO
1155 AM CDT Sat Oct 3 2026

.KEY MESSAGES...

-  Seasonable temperatures continue through Monday, with a
   warming trend Tuesday onward.

-  Dry conditions persist for the foreseeable future.

&&

.SHORT TERM /THROUGH SUNDAY NIGHT/...
Issued at 247 AM CDT Sat Oct 3 2026

Very little has changed regarding this weekend`s forecast, as dry,
seasonable, and downright pleasant conditions will persist. The
primary forecast challenge during this period continues to be the
potential for patchy nocturnal fog development, but even this threat
is expected to be rather limited and should not cause widespread
impacts even if it does materialize.

As mentioned in the previous discussion, our area remains within the
southwestern portion of an expansive area of surface high pressure
centered across the Great Lakes, and this surface high will
gradually slide east today and tomorrow. This will maintain light
winds and a low-humidity continental airmass with minimal cloud
cover, which favors efficient radiative cooling and cool air
drainage in river valleys overnight. So far early this morning, very
little fog has been captured by surface observations, but GOES night
fog imagery does suggest that some fog may be developing in Ozark
river valleys, so we may see some brief visibility reductions in
these areas that are protected from the light easterly winds. Still,
we don`t expect this to be particularly impactful outside of a few
sporadic locations, and this fog will diminish quickly after
sunrise. We may also see a bit of steam fog forming on local main
stem rivers, but this is also not expected to be much of a concern
on land. Another round of similar patchy fog will be possible again
tomorrow night as well, when even lighter winds are forecast.

Otherwise, a slight increase in temperatures is expected today and
slightly more tomorrow afternoon, with highs mostly in the 70s. A
weak, dry cold front will encroach upon the area tomorrow afternoon
thanks to a digging trough across the Great Lakes, but its (minimal)
impact won`t be felt until Monday.

&&

.LONG TERM /MONDAY THROUGH FRIDAY/...
Issued at 247 AM CDT Sat Oct 3 2026

As mentioned above, a digging trough across the Great Lakes
will send a weak, dry cold front into the area late Sunday, which
will only act to slow our weekend warmup briefly Monday. Behind this
front, another expansive area of surface high pressure will shove
any appreciable moisture even further toward the Gulf, and reinforce
a dry, continental airmass across the area. This should drop
temperatures by roughly 5 degrees or so Monday and switch winds to
the north briefly, but otherwise, its effect on sensible weather
will be hardly noticeable.

From Tuesday onward, though, ensemble guidance continues to suggest
that a broad upper ridge across the western 2/3rds of the CONUS
will slowly expand eastward, resulting in gradually building
geopotential heights aloft. Meanwhile, weak south to southwest low
level flow will resume as the second iteration of high pressure
moves eastward, and continues sunny skies will allow for several
days of nearly full insolation. As such, a steady warming trend is
expected through the rest of the work week, and this is supported
by ensemble temperature forecasts. Confidence is high that we
will once again reach well above average (50-80% above 80 degrees
Wednesday onward), but we do note that the NBM ensemble suite is
once again a bit on the warm side of available guidance, and it
may be the result of a slightly overaggressive bias correction.
Still, we`re talking about a difference of 2-4 degrees, and at
these temperature ranges this isn`t a particularly impactful
difference at these temperature ranges.

Finally, due to the continued influence of a very dry airmass and
high pressure, precipitation chances are almost nonexistent
throughout the work week.

&&

.AVIATION /18Z TAFS THROUGH 00Z MONDAY/...
Issued at 1153 AM CDT Sat Oct 3 2026

Confidence is high in dry and VFR flight conditions through the
period. A weak cold front will slowly move through the area
tomorrow, pushing winds to out of the north-northwest.

&&

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

&&

$$

SHORT TERM...19
LONG TERM...19
AVIATION...Elmore