Old Jamestown, Missouri 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

945
FXUS63 KLSX 240855
AFDLSX

Area Forecast Discussion
National Weather Service Saint Louis MO
255 AM CST Tue Feb 24 2026

.KEY MESSAGES...

- Despite high clouds limiting insolation, strong southwesterly
  winds join low humidity and dry vegetation to result in an
  elevated fire danger across much of the region this afternoon.

- A quick-moving system brings a 60% chance for light rain or a
  rain/snow mix (north of I-70) late Wednesday into Thursday. Even
  where snow is more predominant (far northern Missouri), we
  expect no impacts.

- March arrives like the proverbial lion: a potent cold front
  arrives late this weekend, introducing a slightly more active
  pattern across the region.

&&

.SHORT TERM...  (Through Late Wednesday Afternoon)
Issued at 254 AM CST Tue Feb 24 2026

Our anomalously-strong surface ridge that brought chilly
conditions yesterday is but a distant memory, now centered over
the Lower Mississippi Valley. Southerly return flow is becoming
stronger by the hour from west to east thanks to a clipper evident
on GOES-East Mid-Level Water Vapor imagery strengthening a
surface low/cold front and amplifying the pressure gradient over
the central Plains. Also evident on Mid/Upper-Level Water Vapor
imagery is a nearly-unbroken stream of moisture from the Pacific
Coast into the Mid-Mississippi Valley, which is resulting in
overcast cirrus over the region. Warm air advection will intensify
through the morning amidst the strong (20-25mph, gusting to
35mph) southerly winds, promoting much warmer high temperatures
today compared to days prior, particularly across central and
south-central Missouri.

While surface dewpoints are forecast to gradually rise through the
day, guidance is typically too quick to recover moisture in patterns
like these. With dry air still in place to some degree from the
departing high, and the warm southwesterly wind already in place, an
elevated fire danger will exist across much of the region. The only
exception will be in south-central Illinois, where relative humidity
will be just high enough to keep this danger at bay. The high clouds
will throw some higher uncertainty into this forecast, as they will
limit both diurnal mixing and surface warming, but there seems to be
a consensus that the warm advection alone will be enough on its own
to promote the fire danger. For more detail on this threat, please
refer to the Fire Weather Forecast (FWFLSX).

The cold front passes through the region during the late afternoon,
after which winds are actually forecast to weaken as the pressure
gradient slackens. Temperatures behind the front won`t be
drastically cooler with the real teeth of the post-frontal airmass
only skimming northern Missouri. As a result, overnight lows will be
10-20 degrees warmer than the night before. That airmass skirts into
the Great Lakes region through tomorrow morning, resulting in a
cooler easterly wind over much of the region keeping temperatures in
check. There will be some north-south gradient to the highs on
Wednesday, with those north of I-70 feeling the effect of the
easterlies a bit more than those across the Ozarks and southwest
Illinois. Increasing cloud cover ahead of our next precipitation-
producing system will also contribute to more muted daytime
temperatures on Wednesday.


MRB

&&

.LONG TERM...  (Wednesday Night through Monday)
Issued at 254 AM CST Tue Feb 24 2026

A weak shortwave drops through the central Plains Wednesday
afternoon amidst the northwest flow aloft, which will represent our
next precipitation chance across a good portion of the forecast
area. One notable difference in this system compared to 24 hours ago
is the weaker, more progressive nature of the wave. Now a majority
of guidance really fails to amplify the surface cyclone until it is
well east of the region Thursday morning. Subsequently, the NBM
probabilities for 0.25" of liquid precipitation dropped areawide and
now only top out at ~30% in south-central Illinois. With a lack of
more robust mid-level ascent and limited moisture overall, any
precipitation that falls will be light. The probability of any
thunderstorms in southeast Missouri is virtually zero now that
MUCAPE values across all available guidance have diminished. It`s
worth mentioning that model profiles north of I-70 do support a
brief period of rain/snow mix (or even light snow further north near
the Iowa border) with this system. That said, the light rates,
marginal profiles, and warm ground temperatures will work in tandem
to preclude any noticeable impacts.

Most of the day Thursday should be largely dry and somewhat
comfortable with a broad surface anticyclone developing over the bi-
state into the Ohio River Valley. The axis of this ridge quickly
passes to our south and east, bringing a warm, dry southerly return
flow back to us for Friday and sending temperatures to their warmest
values of the week so far. Confidence is high (80%) in highs
exceeding 60 degrees for all except south-central Illinois. With a
strengthening southwest wind and limited cloud cover, those lee of
the Ozarks (Columbia, Jefferson City, and surrounding areas) have a
50-60% chance of making a run at 70 degrees this day as well. We
will also need to watch this day for some degree of fire danger,
with the synoptic pattern looking favorable compared to local
climatology.

Another strong northern stream cyclone draws a cold front closer to
the region Saturday, though the southward progress of this front is
very uncertain and will drastically impact temperatures. While the
current forecast favors a more widespread warm solution, the NBM
interquartile range for high temperatures is 15 degrees or so across
the northern two-thirds of the forecast area. Temperatures are more
confident across southern Missouri, where nearly no guidance brings
the front on Saturday. That said, a reinforcing wave will allow the
front to surge south and a strong surface high (near the 90th
climatological percentile) to advance into the bi-state region to
begin March. While equally-uncertain to Saturday`s temperature
forecast, the entire distribution of the NBM slides much cooler for
Sunday. This uncertainty plagues the remainder of the forecast with
longwave troughing over much of the CONUS and this boundary wavering
north and south through early next week in the Mid-Mississippi
Valley. CPC Precipitation Outlooks and CIPS Extended Analogs from
Saint Louis University both highlight this time period for above-
normal precipitation, which is entirely possible given the stalled
front and some more anomalous precipitable water values (1.0-1.5
standard deviations) lingering in its vicinity. Some of the cooler
solutions may feature a wintry mix Sunday into Monday, but again
little to no impact would occur unless snow became the more
predominant precipitation type.

MRB

&&

.AVIATION...  (For the 06z TAFs through 06z Tuesday Night)
Issued at 1024 PM CST Mon Feb 23 2026

VFR conditions are expected throughout the 06Z TAF period. Light
winds are expected overnight, with steadily increasing high level
cloud cover that will persist for the duration of the period.

Before surface winds increase during the day tomorrow, strong
southwest winds aloft will develop in the morning, and may result
in a few hours of low level wind shear, particularly at COU/JEF.
By late morning, gusty southwest winds will develop near the
surface and reduce the low level wind shear threat, but these
gusty surface winds will continue through late tomorrow afternoon.
Winds will weaken near and after sunset, and a weak cold front
will cause winds to become light and variable overnight.

BRC

&&

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

$$

WFO LSX