Old Jamestown, Missouri 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

523
FXUS63 KLSX 120440
AFDLSX

Area Forecast Discussion
National Weather Service St Louis MO
1040 PM CST Wed Nov 11 2026

.KEY MESSAGES...

- Much colder weather is expected the next several days with a
  widespread freeze this weekend.

- The temperature moderates closer to normal by mid next week
  but rain chances remain minimal.

&&

.SHORT TERM /THROUGH THURSDAY NIGHT/...
Issued at 147 PM CST Wed Nov 11 2026

A potent shortwave trough tracking near Chicago this afternoon is
driving a cold front eastward across our area. Winds pick up out of
the west and dewpoints begin to tumble behind the front. Though with
initially strong mixing it will take a few more hours before colder
surface temperatures are realized. We`ll lose our strongest gusts
tonight, but winds remain elevated in the cold advection.
Temperatures fall back into the upper 30s North to lower 40s South.

While today`s shortwave pushes east toward the New England coast
where a nor`easter develops, a secondary shortwave trough pushes
north to south from the western Great Lakes to the Ohio Valley on
Thursday. This has the net effect of developing a broader trough
stretching from the Midwest to New England. For us locally, the
second shortwave will initiate another surge of cold advection on
Thursday, with winds more northerly this time. With the presence of
the trough aloft, low level cold advection, and shallow instability,
there`s the potential for a few light showers to develop mainly
during the afternoon on Thursday. The REFS shows about a 20 to 30
percent chance of measurable precipitation out of this mainly east
of the Mississippi River. Although temperatures will be getting
colder, especially by Thursday evening, temperatures in the cloud
layer aloft will likely remain too warm for snowflake formation. By
Thursday night the entire region is expected to fall below freezing
as cold advection continues. Since conditions remain fairly well
mixed overnight we`ll see temperatures in the 27 to 30 degree range
area wide with very little local variation.

&&

.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
Issued at 147 PM CST Wed Nov 11 2026

As the upper trough becomes established over the eastern half of the
US, a high amplitude ridge forms over the Great Plains in its wake,
sandwiched between the eastern trough and another trough over the
West Coast. Our area will gradually shift from being under the
influence of the trough to being more under the influence of the
ridge. At the surface, the surface high will have its greatest
influence over our area this weekend yielding light winds and cold
weather. Despite greater sun on Friday, temperatures only reach the
mid 40s for highs. By Friday night, we should see a pretty solid
radiational cooling set up allowing the cold spots to experience a
hard freeze in the low 20s. Saturday night could be just as cold
depending on whether clouds begin to spill into the region.

After this, we`ll see a gradual warm up back toward normal
temperatures for this time of year, in the 50s for highs and near
freezing for lows, through the middle of next week. In prior
forecasts, ensemble guidance was more variable in how quickly we
transitioned out of the cold air mass and into the warmth of the
ridge. However, latest guidance is in better agreement on the idea
of the gradual moderating trend locally. That increased confidence
is shown in the NBM Interquartile Range for high temperatures which
has fallen to 5 degrees or less each day through Wednesday, cutting
the variance in half relative to 24 hours ago.

Rain chances remain minimal through this 7-day forecast period. The
best opportunity is from a southern stream shortwave that tracks out
of the Four Corners and toward the Gulf Coast Sunday into Monday,
undercutting the ridge to its north. Trends continue to keep this
well south of our area, leaving us with only some high level
cloudiness. Latest 12Z LREF guidance shows less than 20 percent of
members with measurable rain in our area. Latest NBM is still a bit
higher with the PoP Sunday night as it is slower to respond to
trends in guidance.

&&

.AVIATION /00Z TAFS THROUGH 06Z FRIDAY/...
Issued at 1037 PM CST Wed Nov 11 2026

VFR flight conditions are expected through the forecast period
at all local terminals. There is a low chance (10-20%) for
brief, light showers during the daylight hours Thursday mainly
at KUIN. If direct impacts are to occur, rain is expected to be
too light to reduce visibilities enough to change flight
category.


&&

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

&&

$$

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