Old Jamestown, Missouri 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

473
FXUS63 KLSX 252028
AFDLSX

Area Forecast Discussion
National Weather Service Saint Louis MO
228 PM CST Wed Feb 25 2026

.KEY MESSAGES...

- Widespread light rain is expected tonight. A few snowflakes may mix
  in across parts of west-central Illinois, but no impacts are
  expected.

- Much colder weather is expected Sunday into Monday behind a
  strong cold front. A wintry mix is looking increasingly likely
  late Sunday through Sunday night, with the best chances (50-60%)
  for travel impacts north of I-70.


&&

.SHORT TERM...  (Through Late Thursday Afternoon)
Issued at 228 PM CST Wed Feb 25 2026

A hybrid clipper is expected to impact us overnight tonight,
bringing mostly very light rain to the region. There looks like
there will be two separate axes where rain chances are highest
(~60%). One is across southeast Iowa east/southeast into eastern
Illinois where low/mid level frontogenesis is strongest. This
should clip parts of our west-central Illinois counties late this
evening until just after midnight. Sounding show a near isothermal
layer straddling the freezing mark toward the end of the
precipitation, so some wet snowflakes mix may mix in with the
rain. However, any accumulations would be very light and confined
to grassy/elevated surfaces. Therefore, no impacts are expected.
Further southeast, another axis of more widespread rain is
expected across parts of central/southeast Missouri tonight where
low-level moisture convergence is strongest. Deterministic
guidance also shows some MUCAPE, though largely beneath the mixed
phase region of the clouds. Therefore kept any thunder mention out
of the forecast, but I wouldn`t be shocked if there was a rumble
or two out there overnight in/near this region. In areas between
these two areas of relatively stronger forcing for ascent, light
rain should be more scattered in nature. Regardless, any
precipitation looks quite light tonight, with most locations only
picking up a few hundredths, if that. The 12Z HREF LPMM only has a
small stripe of 0.10"+ in the moisture advection axis so while a
few lucky locations may see over a tenth of an inch in
central/southeast Missouri.

A weak area of surface high pressure will slide south across the
area on Thursday. Weak low-level cold air advection holds through
the morning before some return flow begins from west to east in the
afternoon. Clouds (low stratus) may linger along/east of the
Mississippi River to about midday. Decreasing clouds though are
forecast from west to east, with a mostly sunny sky areawide by mid-
late afternoon. This sunshine and aforementioned weak return flow
should allow temperatures to climb into the 50s, with some spots of
60 degrees possible in central/southeast Missouri. Coolest locations
should be in parts of south-central Illinois (highs near 50) where
clouds will linger longest.


Gosselin

&&

.LONG TERM...  (Thursday Night through Next Wednesday)
Issued at 228 PM CST Wed Feb 25 2026

(Thursday Night - Saturday Night)

A warming trend is expected to end the work week as 850-hPa
temperatures climb to near +10C late Friday (~90th percentile of
climatology). Surface winds also veer more to the southwest by
Friday afternoon beneath a mostly sunny sky. High temperatures are
forecast to climb to around the 70 degree mark, with the best
chances (50-70%) from the NBM in parts of central/east
central/southeast Missouri where those southwest winds downslope off
of the Ozark Plateau.

Forecast uncertainty increases with respect to temperatures by
Saturday. While the initial cold front should pass through most of
the area late Friday night/Saturday morning, it may stall out across
southern sections of the area. In addition, the real push or arctic
air holds off until later in the day, but the exact timing remains
uncertain. Not surprisingly, the spread for highs is large on
Saturday. The differences between the 25th/75th percentiles is about
15 degrees for most locations. There should be a tight gradient from
north to south, with highs likely about 20 degrees colder in
northeast Missouri/west central Illinois compared to southeast
Missouri.


(Sunday - Sunday Night)

A complex precipitation type event is increasingly likely to take
place across the broader mid/upper Mississippi Valley region late
Sunday through Sunday night/Monday morning. While the specifics will
need to be ironed out over the next several days, the ingredients
are all there for an impactful winter storm. An area of arctic high
pressure (1036+ hPa; ~95th percentile of climatology) is forecast to
settle into the Upper Midwest by Sunday morning, with a steady long
fetch of north/northeasterly winds continuing to advect colder and
drier air into the mid-Mississippi Valley. As was alluded to a
couple of days ago, models tend to struggle with truly arctic air
masses. Given that the air mass currently in Alaska started in
Siberia (typically the coldest source region in the Northern
Hemisphere), I would not be surprised to see a continuing colder
trend to surface temperatures up to about 925 hPa, especially with
the cold front likely to be across the mid south by Sunday morning.
By late Sunday, a midlevel shortwave trough is expected to move east
across the area in conjunction with increasing warm/moist advection
centered around 850 hPa above the low-level arctic air mass. This is
a recipe for a ~12-18 hour period of accumulating wintry
precipitation Sunday afternoon through Sunday night, but how much
falls and where are huge open question marks. This very well may be
quite rare, with an axis of accumulating freezing rain/sleet/snow.
This author cannot recall this type of event in early March over the
past 20+ years. This late in the season, you typically only see
events with rain and/or snow that is dictated by the boundary layer.
While climatology strongly argues for rain/snow only, this is the
type of event that very well may produce impactful freezing rain and
sleet (in addition to snow) somewhere in the region. At this early
point, the best chances of wintry precipitation are north of I-70.
This is where probabilities for at least 0.25" of freezing/frozen
precipitation climb into the 50-60% range. The further north you go,
snow and sleet are more likely with freezing rain and rain becoming
more likely the further south you travel. Road impacts are also not
certain, but any snow/sleet would be more likely to cause issues
Sunday night. Freezing rain may be more likely to not accumulate on
roadways as it should take longer for the road surfaces to cool
below freezing. However, this still may occur later on Sunday night
especially if surface temperatures are in the mid to upper 20s. That
doesn`t look particularly likely, but is possible. Looking at the
cluster analyses, the GEFS is generally further south/colder and
comprises a majority of both clusters which give us more significant
wintry precipitation. However, about 40% of the EPS members are also
in those 2 clusters, so the GEFS does have some support from the
EPS. Additional shifts may occur over the next couple of days, so
please stay tuned for future forecast updates.


(Monday - Next Wednesday)

Forecast uncertainty for next week is quite large, but generally
shows at least a modest warming trend. There could be additional
rounds of precipitation, but most likely in the form of a plain cold
rain and no winter weather.


Gosselin

&&

.AVIATION...  (For the 18z TAFs through 18z Thursday Afternoon)
Issued at 1124 AM CST Wed Feb 25 2026

Increasing clouds with gradually lowering ceilings are forecast
tonight. Rain chances will also increase, mainly in the late
evening/early overnight hours. The best chances (60%) are at KUIN,
and there may be a brief period of -SN mix in as well so kept a
PROB30 group for that potential. Low MVFR ceilings are also
expected to move into KUIN late tonight before improving late
Thursday morning.

Gosselin

&&

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

$$

WFO LSX