Old Jamestown, Missouri 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

361
FXUS63 KLSX 112321
AFDLSX

Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
621 PM CDT Wed Jun 11 2025

.KEY MESSAGES...

- Warm, pleasant weather continues through Thursday with the St.
  Louis and Columbia metro areas potentially reaching 90 degrees
  for the first time this year.

- Increased humidity marks the return of showers and a few weak
  thunderstorms late Thursday that persist through early next
  week.


&&

.SHORT TERM...  (Through Late Thursday Night)
Issued at 136 PM CDT Wed Jun 11 2025

Water vapor imagery reveals a broad trough centered over Texas,
largely detached from the subtropical jet over the northern CONUS
and southern Canada. Given the upper troughs distance from the
jet stream, it will only slowly meander to the northeast and will
be the focus of the forecast for the next several days. Today, the
clearest evidence of that trough approaching the Mid Mississippi
Valley is the shift to southwesterly winds throughout most of the
troposphere. These southerly winds are advecting warmer air into
the region, but are also pulling in deeper moisture and slightly
greater cloud coverage. As of 2pm, temperatures had climbed into
the mid to upper 80s in many areas across the CWA, so we`ll still
make a run at 90 degrees in many locations, but the increasing
thin clouds may keep many locations just shy of that mark.

The upper trough will continue to inch closer to the CWA tonight and
tomorrow, drawing even more moisture into the area. This will
further bolster cloud coverage and thickness, and should keep
temperatures from dropping off too much tonight and a bit of a lid
on temperatures tomorrow. In fact, even the 90th percentile of the
NBM maximum temperature is below 90 degrees for the vast majority of
the forecast area tomorrow. The deeper moisture, combined with
limited forcing on the northeast periphery of the upper low, will
also bring the first chances for rain associated with this system
into the region. Most CAMs have at least a few showers moving across
portions of central and NE MO late tomorrow morning and into the
afternoon, but coverage is expected to be limited due weak
forcing.

BSH

&&

.LONG TERM...  (Friday through Next Wednesday)
Issued at 136 PM CDT Wed Jun 11 2025

By Friday, the upper low will have finally made it to Missouri,
resulting somewhat more robust forcing and even richer moisture
across the Mid Mississippi Valley. In fact, both ECMWF and NAEFS
ensembles push precipitable water to right around the 90th
climatological percentile by Friday afternoon. This deep moisture,
coupled with the transient-but-modest forcing across the region,
will almost certainly bring showers and a few thunderstorms to
the area, especially across our south. That said, given the
limited forcing, showers and thunderstorms will be more scattered
in coverage, and this limited coverage is what`s keeping our
precipitation chances limited to about 80%. The modest forcing
will also limit thunderstorm organization and strength, meaning
that chances for severe thunderstorms are rather low (< 5%). With
slow storm motion and anomalously high moisture, I can`t rule out
locally heavy rainfall, but even those chances are on the low end
(< 10%) as well.

The upper trough will slowly depart the region on Saturday, and
several of the deterministic models have begun depicting a
reinforcing shortwave dropping south into the area on Sunday
afternoon/evening. These features will interact with the lingering
moisture, keeping the chance for showers and thunderstorms in the
region through the weekend, with the highest chances in the
afternoon and early evening. We`ll be at least partly cloudy on
both days as well, limiting temperatures to the low to mid 80s. As
we move into next week, the upper level pattern becomes a bit
more zonal, with most models showing a series of weak shortwaves
pushing through the region. This will keep rain chances in the
forecast through at least the first part of next week along with
seasonal temperatures.

BSH

&&

.AVIATION...  (For the 00z TAFs through 00z Thursday Evening)
Issued at 620 PM CDT Wed Jun 11 2025

VFR conditions continue tonight into tomorrow with light southerly
winds. Increasing high level cloud cover this evening and
overnight should prevent any valley fog overnight. Clouds thicken
through the day on Thursday but will remain in the VFR range.

Kimble

&&

.CLIMATE...
Issued at 620 PM CDT Wed Jun 11 2025

St Louis still hasn`t reached 90 yet in 2025. This puts 2025 in
the Top 20 all time latest dates of the first 90 degree
temperature, and the latest in at least 30 years (Jun 19, 1995).
The all time latest first 90 degrees was July 4 in both 1961 and
1912. Records began in St Louis in 1874.

Columbia has also not yet seen a 90 degree reading in 2025. The
latest date of first 90 degrees on record was July 14, 1904.
Records began in Columbia in 1890.

Quincy reached 90 degrees on May 15 of this year.

Based on the current forecast, our next best chance to see 90
degrees is around June 17.

Kimble

&&

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

$$

WFO LSX