Old Jamestown, Missouri 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

066
FXUS63 KLSX 211048
AFDLSX

Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
548 AM CDT Thu May 21 2026

.KEY MESSAGES...

- The cool weather will continue through Friday before temperatures
  return to near normal over the Memorial Day weekend.

- There will be multiple chances for showers and few thunderstorms
  over the next 7 days with the greatest chance on Friday
  (70-90%).


&&

.SHORT TERM...  (Through Late Friday Afternoon)
Issued at 329 AM CDT Thu May 21 2026

Dry and cool weather was found across the area this morning as our
weather is being dominated by high pressure centered over the Great
Lakes.  This high is causing the northeasterly surface winds which
are bringing in dry and cool air into the region.  The HREF is
showing this high moving east today which will shift our surface flow
out of the east keeping the weather dry until late tonight. This is
when the short terms models bring the shortwave trough currently
near the Rio Grande northeastward into the Midwest by late tonight.
The LREF is showing PWATS between 1.4-1.8" with decent ascent
supporting the going 60-90% POPs across the area on Friday with the
greatest PoPS over the southeast half of the CWA.   The associated
surface low track is staying south of the CWA keeping available
instability low for mid-late May.  Will keep with just a slight
chance of thunderstorms during the afternoon.

Highs will be a few degrees warmer today than yesterday allowing
highs to climb above 70 degrees in most areas.  Tomorrow will be
cooler with the clouds and rain.

Britt

&&

.LONG TERM...  (Friday Night through Wednesday)
Issued at 329 AM CDT Thu May 21 2026

The LREF is continuing to show that the upper flow will stay out of
the southwest through next week with a number of upper troughs
moving through the area at the same time.  The two most notable
troughs at this point look to move across the CWA on Sunday and
Tuesday when 40-60% of the LREF members are producing rain across
the area.  It should be noted that least 20-30% of the members are
producing some rain each period, particularly over the southeast
half of the CWA which will be closer to a surface front that remains
stalled under the southwesterly flow.

Temperatures will slowly warm up closer to normal over the weekend
into next week as the LREF is showing a ridge building over the
Midwest.  While we should see some increase in temperatures, the
warmup should be tempered by the clouds and rain chances and not as
high as the NBM which is on the warmest side of the temperature
guidance.

Britt

&&

.AVIATION...  (For the 12z TAFs through 12z Friday Morning)
Issued at 538 AM CDT Thu May 21 2026

Mainly dry and VFR conditions are expected through at least 06Z
tonight. Then there will be an increasing chance of showers and
few thunderstorms after 06Z tonight, though the chance doesn`t
rise above 30% except at STL until after 12Z. At STL the chance
for showers increases above 60% by mid morning on Friday, so have
included a TEMPO group for -RA with MVFR ceilings and
visibilities. Otherwise, winds will remain out of the east to
northeast at less than 10 knots.

Britt

&&

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

$$

WFO LSX