Old Jamestown, Missouri 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

336
FXUS63 KLSX 021129
AFDLSX

Area Forecast Discussion
National Weather Service St Louis MO
629 AM CDT Sun Aug 2 2026

.KEY MESSAGES...

- The sun comes out today and brings warmer weather, but still
  well below normal for summer standards. Temperatures gradually
  warm back up the rest of the week.

- After several dry days to start the week, shower and
  thunderstorm chances increase for the middle to later part
  of the week.

&&

.SHORT TERM /THROUGH MONDAY/...
Issued at 213 AM CDT Sun Aug 2 2026

Vertically stacked low pressure that brought the cloudy, cool,
and drizzly weather yesterday is moving very slowly to the east.
This morning it`s located near Indianapolis, and over the course
of the day is expected to weaken and shear out as it moves east.
One part moves into the eastern Great Lakes while part of it
gets stuck over the southern Appalachians this week. A
subsident upper level flow in the wake of the departing trough
will promote drying with an elongated surface high pushing
southeast through the Plains and the western Great Lakes today.
The result for us locally will be decreasing clouds from west to
east, with lingering drizzle ending during the morning. More
sun today will allow the temperature to warm up about 10 degrees
over yesterday`s daytime levels, but that`s still nearly 10
degrees below normal for early August. The warmest weather will
be in the west where we`re likely to see a full day of sun,
while the cooler conditions will be in the east where clouds
linger a little longer.

The surface high pressure axis moves into the region overnight
tonight leading to calm winds and what is likely our coolest
night of this air mass. Temperatures drop into the low 60s for
many areas, and by morning there could be some patchy fog in
spots. Monday will see yet another day of the August sun working
to modify this air mass. We`ll add a few degrees to the
temperature, warming into the low to mid 80s. At the same time
we`ll be mixing a bit deeper as well, allowing even lower
dewpoints during the afternoon. Still a very pleasant day by
August standards.

&&

.LONG TERM /MONDAY NIGHT THROUGH SATURDAY/...
Issued at 213 AM CDT Sun Aug 2 2026

As we go through this week we`ll see western US ridging get
suppressed to the south as a trough moves through Canada and the
northern tier of the US. This trough eventually settles into
broad troughing through central North America with ridging on
either side, over the western US and the western Atlantic. Our
area will be near the base of the trough for a few days in the
middle to later part of this week before ridging becomes more
expansive across the southern half of the US this weekend. The
impacts for us locally will be increased rain chances as the
base of this trough nears our area.

At the surface, high pressure weakens as it moves east on
Tuesday. Our flow locally turns weakly southerly with at least
one more dry day in store for us. Temperatures again warm
another couple of degrees with another day of sun, putting us
back into the mid to upper 80s. Meanwhile, as the initial trough
moves by to our north it sends a cold front southeast through
the Northern Plains. By Wednesday this front settles into a
roughly west to east position across Nebraska and Iowa. A weak
disturbance tracking along it will trigger a round of
thunderstorms to our west on Wednesday, with these storms moving
east overnight into Thursday morning. Rain chances with this
round are greatest in the northern portion of our forecast area,
closer to the front. However, this first round of storms may
help to push the front southward into our area with the
potential for additional storms to form near this front Thursday
night into Friday and then maybe again Friday night into
Saturday. Confidence is greatest with the first round of storms.
The subsequent rounds depend in part on how the first round
progresses, resulting in greater uncertainty on where the
subsequent rounds form and track. Regardless this Wednesday
night through Saturday period is our best chance for rain this
week. The severe weather threat looks low, but with increasing
moisture available we could see locally heavy rainfall depending
on how the rounds of storms evolve.

When it comes to temperatures we have strong confidence in a
warming trend continuing through Wednesday. NBM interquartile
spread for high temperatures remains at a modest 2 to 3 degrees
each day through Wednesday, reflecting a strong consensus among
guidance through this warm up. However, that spread increases to
7 degrees or more Thursday through the weekend, indicating lower
consensus during this period. This uncertainty is driven largely
by the position of that front and any convection or related
cloud cover along it limiting heating each day. On days where we
see more sun, we`ll rise into the low 90s, but with more clouds
or a more southward push of the front we likely stay in the mid
80s.

&&

.AVIATION /12Z TAFS THROUGH 18Z MONDAY/...
Issued at 628 AM CDT Sun Aug 2 2026

Low MVFR ceilings are expected to advect out of metro St. Louis
around mid morning. Dry/VFR conditions are then forecast for the
remainder of the TAF period. Some light gusts out of the north
are expected today before winds subside and become
light/variable tonight.

&&

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

&&

$$

SHORT TERM...Kimble
LONG TERM...Kimble
AVIATION...Gosselin