Old Jamestown, Missouri 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

920
FXUS63 KLSX 100853
AFDLSX

Area Forecast Discussion
National Weather Service St Louis MO
353 AM CDT Fri Jul 10 2026

.KEY MESSAGES...

- A flash flood watch is in effect through tonight in southeast
  Missouri and southwest Illinois. Heavy rain can be expected
  with showers and thunderstorms this afternoon through tonight.

- Thunderstorms this this afternoon/evening may be strong to
  severe with damaging winds being the primary threat.

- Conditions trend drier with above normal temperatures Sunday
  through the middle of next week.

&&

.SHORT TERM /THROUGH SATURDAY NIGHT/...
Issued at 343 AM CDT Fri Jul 10 2026

The broader complex of thunderstorms have shifted into southeast
Missouri and southwest Illinois with isolated showers and perhaps a
thunderstorm northward through I-70. Coverage and intensity is
expected to gradually wane through sunrise with patchy fog along and
north of I-70 through early this morning. Another round of active
weather is expected with increasing potential for thunderstorms this
afternoon through late evening. Some of the thunderstorms will be
capable of producing damaging winds, very heavy rain, and flash
flooding through late tonight.

Water vapor imagery shows the first complex of thunderstorms moving
into southern Illinois and western Kentucky with a narrow corridor
of heavy rain and a few thunderstorms that extend northwestward
through Rolla. A second area of thunderstorms extends through
central Nebraska and Kansas. At the surface, a stationary
boundary stretches through northern Missouri and Illinois with
an expansive pool of moisture shrouding the region with
dewpoints in the upper 60s to mid-70s. Some clearing has given
rise to patchy fog with calm/light and variable surface winds,
but fog should not become too extensive with additional cloud
cover moving in from the west.

The initial round of thunderstorms that moved to the southeast
have left an outflow boundary/trough in their wake. This has
been the focus for ongoing heavy rainfall over southwest
sections of the CWA, where radar estimates show 1-3 inches of
rain has fallen from parts of central Missouri through southeast
Missouri with as much as 5-7+ inches of rain in a narrow
corridor over southern Crawford County into Iron, Reynolds, and
Madison Counties. This is particularly concerning with more
active weather on the way today/tonight. An outflow/trough from
this initial round remains parked over southern sections of the
CWA, extending west to east underneath nearly uniform westerly
flow from the surface through the vertical extent of model
soundings. An MCV tracks into Missouri later today, providing
yet another boost to thunderstorms this afternoon/evening. While
hi-res guidance has a general idea of what may transpire, what
happens between now and this afternoon will influence the next
wave. RAP guidance shows MUCAPE building to around 3000-3800
J/kg south of I- 70. The shortwave/MCV passes somewhere through
the northern half of Missouri, laying out another outflow
boundary as the LLJ re-intensifies late this evening. The
potential for strong to severe thunderstorms is most likely to
be associated with the increasing LLJ and another complex of
thunderstorms this evening into tonight. The primary threat will
be damaging winds, though marginally severe hail will be
possible with initial cell development. Fragments of vorticity
are ejected eastward and ride overhead through the day, which
could lead to earlier development ahead of the complex. This
leaves plenty of uncertainty in the exact solution, though there
is higher confidence in the flash flood threat. Considering the
rain that has already fallen, additional heavy rain will most
certainly exacerbate already high rivers and streams in areas
already hard-hit. The active corridor ever-so-slowly sinks
southward through the weekend. However, where this lines up,
will be of high interest. Additional rain chances for scattered
thunderstorms extend into Saturday before relatively drier air
is funneled in on northeast flow around the Great Lakes surface
high. Those in areas hit by heavy rainfall should pay very close
attention to the latest forecast updates and any local
emergency guidance, should additional heavy rainfall develop
over the same areas.

Urban areas will approach 90 degrees today. Otherwise, highs in the
80s and lows in the mid-60s/low-70s will be representative for much
of the area.

&&

.LONG TERM /SUNDAY THROUGH THURSDAY/...
Issued at 343 AM CDT Fri Jul 10 2026

The general theme in long range guidance is for the strengthening
and eastward expansion of the western upper level ridge. While the
ECM/GFS both indicate the ridge extending across the northern U.S.,
the ECM is notably stronger with 500mb heights exceeding 6000m. This
is more classic of a mid-summer heat ridge that drives convective
complex around its outer periphery. At the moment, both long range
solutions would place the greatest height rises to the north, saving
the local area from excessive heat, while also steering
northeasterly flow into the region. This effectively shunts some of
the higher moisture value to the south, while placing the more
potent convective trends outside the CWA. That being said, NBMs
blended guidance shows low chances (20-30%) occasionally glancing
the southern sections of Missouri and Illinois. By-and-large, the
pattern would favor drier, warmer conditions with a return to the
90s. Considering that dewpoints are 5-10 degrees lower (60s vs.
70s), excessive heat does not currently look to be a high concern,
though the placement and strength of the ridge will determine how
far dewpoints actually drop.

&&

.AVIATION /00Z TAFS THROUGH 06Z SATURDAY/...
Issued at 1048 PM CDT Thu Jul 9 2026

Main concern with the TAFs is the potential for thunderstorms,
as otherwise conditions should remain VFR with light winds. This
evening`s batch of thunderstorms is expected to remain south of
the TAF sites and ends shortly after 06Z anyway. Another round
of storms is possible in the afternoon on Friday, arriving from
the west and pushing eastward through the evening. Confidence
remains somewhat low on the timing and track of the wave
triggering this, but for now we have included PROB30 remarks for
the time period where storms are most likely at each site.

&&

.LSX WATCHES/WARNINGS/ADVISORIES...
MO...Flood Watch through Saturday morning for MOZ072>075-084-085-
     099.
IL...Flood Watch through Saturday morning for ILZ079.

&&

$$

SHORT TERM...Maples
LONG TERM...Maples
AVIATION...Kimble