Old Jamestown, Missouri 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

945
FXUS63 KLSX 232046
AFDLSX

Area Forecast Discussion
National Weather Service Saint Louis MO
246 PM CST Mon Feb 23 2026

.KEY MESSAGES...

- A rapid warmup is expected on Tuesday, helping bring elevated
  fire danger across parts of central, eastern, and southeast
  Missouri.

- A round of light rain is forecast across much of the area late
  Wednesday night through Thursday.


&&

.SHORT TERM...  (Through Late Tuesday Afternoon)
Issued at 245 PM CST Mon Feb 23 2026

A strong (~1038 hPa; >98th percentile of climatology) surface
anticyclone is currently entering northwest Missouri early this
afternoon. This feature will slide southeastward and weaken with
time, cross the Mississippi River around midnight. Increasing
southerly flow will commence in its wake, but particularly across
portions of central/northeast Missouri. This is where temperatures
are actually expected to rise overnight from the low 20s into the
mid 20s. Further southeast, winds should stay light enough
(particularly in river valleys) to allow temperatures to cool for
much of the overnight hours. Lows in the mid to upper teens are
forecast for those aforementioned east central and southeast
Missouri valleys. In these sheltered areas, winds may stay
light/variable up to about 1200 UTC. Given a mostly clear sky and
low dewpoints, it is a pretty good setup for radiational cooling.

Southerly winds will continue to increase during the day on Tuesday
as the pressure gradient tightens. Very strong low-level warm air
advection is forecast to take place during the day on Tuesday,
helping to warm surface temperatures significantly compared to this
afternoon. However, there should be a fair amount of mid/high level
cloud cover as deterministic RH plots show >90% at between 500 and
300 hPa. These clouds should put at least a lid on some of the
warming, though highs are still expected to get into the mid 40s
(east) to upper 50s (west). These warmer temperatures though will
not only be muted by the clouds, but also the wind. Sustained
southwesterly winds of 15-20+ mph and gusts of 30-40 mph will make
it feel quite a bit chillier than the ambient air temperatures.


Gosselin

&&

.LONG TERM...  (Tuesday Night through Next Monday)
Issued at 245 PM CST Mon Feb 23 2026

(Tuesday Night - Wednesday)

A cold front is forecast to move through the region Tuesday night,
bringing in some "cooler" air back into the mid-Mississippi Valley.
The front itself should pass through dry, with weak moisture return
and the stronger mid/upper level forcing for ascent staying across
the Great Lakes. Temperatures Wednesday afternoon are forecast to
range from the mid 40s to upper 50s from north to south, which still
would be about 5 degrees above normal for the date.


(Wednesday Night - Thursday)

The focus for Wednesday night into Thursday morning remains on the
chances for light rain associated with a hybrid clipper like
disturbance. Light rain should begin Wednesday night as low-level
moisture convergence strengthens and a midlevel shortwave trough
quickly transverses the mid-Mississippi Valley. Rain should end
Thursday morning as a weak surface low or inverted trough swings
through parts of central/southeast Missouri. Rainfall amounts look
quite light, with probabilities for >0.10" on the LREF only in the
30-50% range. There also could be some wet snow mixed in across west-
central Illinois where there is enough wetbulbing to cool the
boundary layer sufficiently for snow to mix in with the rain. Any
accumulations look light, and given the warm and possibly wet
ground, no impacts are expected to transportation/roadways.

Thursday should be the coolest day after this afternoon for the
remainder of the work week. High temperatures are forecast to range
from the mid 40s to mid 50s from northeast to southwest, though the
exact highs will depend on how quickly the hybrid clipper and
residual cloud cover exits the region.


(Thursday Night - Friday Night)

Moderating temperatures are forecast once again to end the work week
as ensemble guidance depicts rising mid/upper level heights and
increasing low-level warm air advection. Highs in the 60s are
forecast areawide on Friday. Unlike Tuesday, there also does not
look like much in the way of cloud cover. Therefore, confidence is
pretty high in those high temperatures. The latest NBM also agrees,
with only a small deviation between the 25th/75th percentiles (~5
degrees).


(Saturday - Next Monday)

Forecast uncertainty increases sharply this weekend and into early
next week. Ensemble guidance shows strong mid/upper level troughing
moving near the US-Canadian border early this weekend. A shot of
arctic air (with Siberian origin) should move southward into the
CONUS. The key questions are how far south and east and how much
does it modify before reaching our area? Conceptually, an arctic air
with this source region would seem more liable to ooze further
southeast than modeled. This is a common bias in the medium range.
In addition, there is not much in the way of southeast CONUS ridging
either. Spread between the 25th/75th percentiles is about 40 degrees
for Sunday highs and nearly 50 degrees between the 10th/90th
percentiles. At this early juncture, erring toward the colder side
is most likely the prudent approach given the source region of the
incoming air mass and the tendency for low-level arctic air to have
trouble stopping its southward push once it enters the CONUS.

Temperatures at the surface (and aloft) will be important as
precipitation chances increase Sunday into Monday. Increasing low-
level moisture convergence atop what could be at least seasonably
cold air may yield some wintry precipitation. If this were a month
ago, I would feel more confident saying a mixed bag (rain, freezing
rain, sleet, and snow) were all possible at least regionally, but it
is climatologically extremely difficult to see significant mixed
wintry precipitation this late in the season. Typically, it is
either rain or snow that is governed by the boundary layer. That
still very well may be the case, but at least the setup is one that
may produce some sleet and freezing rain somewhere in the region.


Gosselin

&&

.AVIATION...  (For the 18z TAFs through 18z Tuesday Afternoon)
Issued at 1122 AM CST Mon Feb 23 2026

Dry/VFR conditions are forecast tonight through Tuesday morning.
Northwest winds slacken off later today and then become
light/variable. Winds turn out of the south early Tuesday and then
become gusty by mid/late morning. Low-level wind shear is also a
concern late tonight into early Tuesday morning at the central
Missouri terminals where winds 2kft AGL are near 40 knots with
light southerly flow at the surface.

Gosselin

&&

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

$$

WFO LSX