Old Jamestown, Missouri 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

001
FXUS63 KLSX 060744
AFDLSX

Area Forecast Discussion
National Weather Service Saint Louis MO
244 AM CDT Mon Apr 6 2026

.KEY MESSAGES...

- Rain is expected to change over to snow overnight tonight within
  a narrow band across portions of northeast Missouri and west-
  central Illinois. Accumulations up to 2" are possible, mainly on
  elevated/grassy surfaces.

- A warming trend begins Wednesday, with above normal readings
  through the weekend along with chances of showers and
  thunderstorms.


&&

.SHORT TERM...  (Through Late Tuesday Afternoon)
Issued at 243 AM CDT Mon Apr 6 2026

A secondary cold front is currently near a KMBY>>KUIN line as of
0700 UTC and is moving southeast. The front is forecast to exit
the area later this morning, providing a reinforcing shot of
seasonably cool air into the region. Highs in the mid 50s to mid
60s are forecast from north to south this afternoon beneath
plentiful sunshine.

Increasing clouds are forecast early this evening, mainly across
northeast Missouri and west-central Illinois. Weak low-level
moisture convergence combined with strong low/mid level
frontogenesis and a weak shortwave moving across the area is
expected to yield a northwest to southeast band of precipitation.
This precipitation probably will start off as rain, but wetbulbing
should allow for a transition to snow within the band. A pronounced
layer of dry air evident on forecast soundings centered around 875
hPa may delay the onset of precipitation. However, it is not
particularly deep and the mesoscale forcing strengthens through the
evening. While there are some subtle placement differences, there is
increasing confidence that the low/mid level frontogenesis will be
strong enough to produce at least some minor snowfall accumulations
in the far northern CWA. Higher resolution guidance is most bullish,
though sometimes they can overdo the mesoscale forcing. That being
said, these types of events can be on the "sneaky" side and produce
quite a bit of snow within the heart of the band. At this time, it
looks like accumulations up to 2" are possible in parts of northeast
Missouri through early Tuesday morning. Accumulations should be
mainly confined to elevated/grassy surfaces given the warm ground
and marginal surface temperatures (lows near freezing). However, I
cannot rule out some minor road impacts within the heart of the band
if stronger mesoscale forcing does indeed pan out. The HREF does
have probabilities up to around 30% for at least 0.5"/hr snowfall
rates, which is a pretty decent signal from previous experience.
These probabilities also remain quasi-stationary over the same areas
for about ~3-4 hours. Those types of rates with enough longevity
would have the potential for road impacts, but confidence in that
occurring is low. Therefore, there are no plans for a winter weather
advisory at this time.

Any lingering rain/snow should lighten up and then cease Tuesday
morning as the frontogenetical forcing abates. The remainder of the
day Tuesday should then be dry and cool for early April standards.
Clouds are also expected to linger, particularly across northern
sections of the forecast area. Highs may struggle to get out of the
lower 40s in those locations, with mainly 50s expected further to
the south.


Gosselin

&&

.LONG TERM...  (Tuesday Night through Sunday)
Issued at 243 AM CDT Mon Apr 6 2026

(Tuesday Night)

A seasonably cool night is expected Tuesday night, though increasing
southeasterly winds at the surface and clouds should prevent any
threat for frost. Lows in the upper 30s to mid 40s are forecast from
northeast to southwest across the bi-state area.


(Wednesday - Sunday)

A fast warming trend is expected to begin on Wednesday as low-level
warm air advection increases across the mid-Mississippi Valley.
Highs back near 70 degrees are expected, or about 5 degrees above
normal for the date.

Seasonably mild temperatures are forecast to continue through the
weekend, though exact highs are uncertain due to the possibility of
thicker cloud cover and increasing chances of showers and
thunderstorms. The overall pattern looks unsettled, with a surface
cold front moving toward the region Thursday/Thursday night. The
boundary then may become quasi-stationary, with multiple weak
surface waves moving across the boundary into the weekend. Exactly
where this boundary stalls out and how it evolves through the
weekend is uncertain, but it does look like there is at least a
chance of showers and thunderstorms each day.


Gosselin

&&

.AVIATION...  (For the 06z TAFs through 06z Monday Night)
Issued at 1040 PM CDT Sun Apr 5 2026

VFR flight conditions are expected to prevail through the period.
Light and variable winds will turn to the northwest Monday morning
with some gusts to around 20 mph into early afternoon.

Carney

&&

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

$$

WFO LSX