Old Jamestown, Missouri 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

980
FXUS63 KLSX 232345
AFDLSX

Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
645 PM CDT Sat May 23 2026

.KEY MESSAGES...

- Despite daily rain chances for at least portions of the area
  through next week, rain will not be continuous, and plenty of
  dry time is expected.

- Confidence is high that the area will remain free of severe
  thunderstorms and flooding through next week.


&&

.SHORT TERM... (Through Monday Night)
Issued at 208 PM CDT Sat May 23 2026

Water vapor imagery currently shows a series of shortwaves moving
eastward through the Great Plains and toward the Midwest. The
primary wave is moving northward into Canada, taking its associated
surface low with it. The attendant cold front can be seen in surface
observations extending southward out of the Upper Mississippi Valley
into Missouri and eastern Kansas. Weak convergence along the front
has yielded scattered showers and thunderstorms currently across
northeastern Missouri into southwestern Missouri. Despite the up to
1,500 J/kg of MLCAPE immediately ahead of the front, the storm mode
is expected to be single to multicellular thanks to weak (< 20kts)
of deep layer shear, mitigating a threat of severe thunderstorms.
Brief downpours, frequent lightning, and a quick hit of small hail
are the main concerns with these storms as they move eastward
through this evening. Diminishing instability tonight will cause
convective coverage and intensity to wind down, with rain chances
clearing the CWA to the east during the morning hours. Another round
of fog can`t be ruled out early tomorrow morning as moisture pools
along the boundary.

Sunday is expected to be largely dry aside from a low chance (up to
30%) for isolated to scattered showers and thunderstorms over far
southeastern Missouri and southwestern Illinois during peak heating.
Given the weakness of tonight`s front, weak to no northwesterly post-
frontal flow, and the airmass being Pacific, tomorrow`s temperatures
will be similar to those today. However, mostly sunny skies may
cause conditions to feel warmer for those who venture outside.

On Monday (Memorial Day), guidance consensus is that upper-level
ridging will amplify over the central CONUS, strengthening south-
southwesterly low-level flow over the Middle Mississippi Valley. The
resulting warm air advection will provide a bump in temperatures
compared to what is expected on Sunday. A Bermuda High and weak
surface low over Texas will strengthen the fetch of Gulf moisture
feeding into the Ohio Valley that will keep cloud cover relatively
dense over portions of southeastern Missouri and southwestern
Illinois. Here, temperatures may not see much of a change from
Sunday thanks to reduced insolation. The deeper moisture has a low
chance (20-30%) of yielding an isolated shower or two in the same
portion of the region, but most of the area is expected to remain
dry on Monday.

Elmore

&&

.LONG TERM... (Tuesday through Next Saturday)
Issued at 208 PM CDT Sat May 23 2026

The forecast through the extended range will be driven mostly by an
Omega Block-esque pattern, with the overall pattern still remaining
transient. The upper-level ridge axis will be centered over the
middle of the CONUS, keeping low to mid-level flow out of the south-
southwest through the workweek. This supports daily temperatures
holding around or just above climatological normals through at least
Thursday, with global ensembles having very little spread on this
solution. Weak disturbances under-cutting the ridge will provide
daily rain chances; though, given the subtlety of these features,
confidence is low in specifics on timing and placement of rainfall.
The near continuous chance for rain across portions of the CWA
during this stretch of the period is due to the number of sources
being blended into the NBM. Looking at any one solution shows that
there will not be continuous rain, with plenty of stretches of dry
time expected.

For Friday into next weekend, guidance diverges on the handling of
the Omega Block. Notably, the GFS/GEFS favors a stronger eastern
trough that retrogrades into the central CONUS, favoring cooler high
temperatures Friday and Saturday. The ECMWF/ENS keeps the ridge axis
closer to the Middle Mississippi Valley and has a relatively weaker
eastern trough that would support little to no impact to
temperatures. Despite the spread, a majority of global ensemble
members do support at least a slight cool down starting Friday, and
that is reflected in the current forecast.

Elmore

&&

.AVIATION...  (For the 00z TAFs through 00z Sunday Evening)
Issued at 638 PM CDT Sat May 23 2026

A weak cold front is producing showers and thunderstorms across
central and northeast Missouri into west central Illinois this
afternoon. Storms have been weakening over the past hour and I
expect this weakening trend to continue as daytime heating wanes
this evening. However, it is likely that scattered showers and
possibly a thunderstorm or two will continue into east central and
southeast Missouri this evening and then into parts of southwest
and south central Illinois. Expect mainly VFR flight conditions
outside of showers and storms this evening, with a brief period of
MVFR or even IFR visibility in the stronger thunderstorm cells.
Have also noticed a few wind gusts up to around 25kts with the
stronger storms. Areas that receive precipitation will be prone to
patchy fog tonight, particularly in central and northeast Missouri
where ceilings are likely to clear out just before sunrise on
Sunday morning. Any fog that develops should dissipate quickly
after sunrise.

Carney

&&

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

$$

WFO LSX