Old Jamestown, Missouri 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

983
FXUS63 KLSX 141043
AFDLSX

Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
543 AM CDT Sun Jun 14 2026

.KEY MESSAGES...

-Cool and largely dry conditions are expected today and Monday with
highs in the 70s.

-Thunderstorm chances return Tuesday and linger into the end of the
work week with the best chance Wednesday into Thursday.


&&

.SHORT TERM...  (Through Late Monday Afternoon)
Issued at 320 AM CDT Sun Jun 14 2026

Convection from earlier in the evening has weakened considerably and
is continuing to shift southeastward as the low-level jet veers,
keeping most of the precipitation outside of the CWA. The cold front
remains stubbornly in our north, draped from the KC metro area to
Moberly, MO, to Chicago. Through the morning a disturbance within
the quasi-zonal mid-level flow is expected to kick the front
southward. As it does, cold, dry air advection will push into much
of the area and will work together with lingering cloud cover to
keep temperatures peaking in the 70s areawide. If the front is
slower to move through the area than anticipated, temperatures will
be able to warm more than currently forecast, particularly in
southeast Missouri and southern Illinois.

While the cold air advection will abate by Monday, cool 850 mb
temperatures near 8-10C will result in another day with temperatures
in the 70s to just at 80 degrees. Under the influence of a surface
high in the wake today`s cold front, conditions will be dry and the
sky largely clear.

Delia

&&

.LONG TERM...  (Monday Night through Saturday)
Issued at 320 AM CDT Sun Jun 14 2026

By Tuesday the pattern starts to shift again, as southwest flow
reestablishes in the low levels and the previously mentioned surface
high exits the region. A cold front with weak convergence will move
through the region Tuesday into Wednesday, bringing low chances for
showers and thunderstorms. The better chance for rain will be
Wednesday into Thursday when another, more robust system moves into
the forecast area. Aided by mid-level disturbances on the southern
edge of a trough over south-central Canada, a surface low will drop
through the Great Lakes region, bringing a cold front through the
mid-Mississippi Valley sometime between Wednesday afternoon and
overnight, enhanced by a strong low-level jet. Ahead of the front
southwesterly flow will bring warm, moist air into the region,
though how much remains uncertain. Guidance indicates anywhere from
1000-3000 J/kg of MUCAPE may be available during the
afternoon/evening, which would result in anything from little to no
severe weather, all the way to robust chances for severe weather.
Strong shear between 40-50kts (0-6 km) will be able to organize
anything that develops, but will need instability closer to the high
end of the range to balance it and promote storm longevity. Despite
the favorable synoptic set up, many mesoscale details and timing of
synoptic features remain elusive at this time range and will need to
be watched moving forward. Beyond severe weather, the risk for flash
flooding will also need to be monitored as this pattern is similar
to the frontal pattern for flash flooding and will be paired with
warm cloud depths and high PWATs near 2".

Behind this primary cold front that will move through between
Wednesday and Thursday, a secondary cold front is expected sometime
Thursday. The timing of these features and their speed will
determine how long showers and thunderstorms linger across the area,
with some guidance keeping precipitation in the forecast area into
Friday morning.

Confidence is increasing that Wednesday will be the warmest day of
the week with the warm air advection along the strong southwesterly
flow, resulting in temperatures near to just a few degrees above
normal for this time of year. Beyond Wednesday the temperature
forecast is more uncertain given the timing of fronts, cloud cover,
and precipitation, but guidance overall shows a slight cooling trend
to bring high temperatures a few to several degrees below normal for
the end of the period.

Delia

&&

.AVIATION...  (For the 12z TAFs through 12z Monday Morning)
Issued at 528 AM CDT Sun Jun 14 2026

Rain has largely exited the region, except for weak showers that
have developed from central Missouri into west-central Illinois
along the elevated cold front. These are expected to be short
lived and very light, with little to no impact at the terminals,
should they move over the terminal space. These showers are
expected to dissipate within the first few hours of the TAF
period.

The cold front is dropping into the region this morning, causing a
wind shift to the north and MVFR ceilings near the front. Ceilings
have been somewhat delayed in their arrival and spotty in their
coverage compared to the previous forecast, suggesting that they
may hang on a little longer than originally forecast as well. Once
these clouds and the cold front clear the terminals, dry and VFR
flight conditions will prevail under the gusty northerly winds.
Gusts will diminish with sunset.

Delia

&&

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

$$

WFO LSX