Old Jamestown, Missouri 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

473
FXUS63 KLSX 302331
AFDLSX

Area Forecast Discussion
National Weather Service St Louis MO
631 PM CDT Thu Jul 30 2026

.KEY MESSAGES...

- Showers and thunderstorms become likely late tonight into
  Friday. A few thunderstorms could be strong to severe with
  damaging winds and locally heavy rainfall Friday afternoon and
  evening. A brief tornado is possible, though the threat is
  highly conditional.

- A few showers linger into Saturday with cooler than normal
  temperatures expected through the weekend.

&&

.SHORT TERM /THROUGH FRIDAY NIGHT/...
Issued at 253 PM CDT Thu Jul 30 2026

Clouds have struggled to expand eastward as they run into height
rises east of the Mississippi River this afternoon. Pleasant weather
continues with partly to mostly sunny skies and temperatures falling
from the 80s into the 70s through this evening. Precipitation
chances increase from west to east after midnight as showers and
thunderstorms approach the region from eastern NE/KS.

The nocturnal LLJ is expected to intensify late this evening and
overnight. The nose of the jet is pointed near the NE/KS border,
where showers and thunderstorms are expected to organize and track
east-southeast along the northern periphery of the upper ridge.
Fortunately, thunderstorms are moving into the area during diurnal
minimums with remnant activity expected to weaken. Gusty winds may
precede thunderstorms as outflow outpaces convective activity
through early Friday morning. Early day showers and thunderstorms
lend uncertainty to the severe thunderstorm potential Friday
afternoon into Friday evening. The spatial and temporal window is
short with cloud debris potentially limiting afternoon instability.
If clouds give way to sunshine, instability could be reinvigorated
to around 3000 J/kg along and just ahead of the front. This is,
unfortunately, where there is narrow overlap in low level SRH of 200-
300 m/s2 with 21z FRI hodographs showing support for rotating
thunderstorms. On the other side of the coin, if cloud cover and
showers keep surface conditions cooler, instability will fail to
recover to levels needed to deepen updrafts with a low threat for a
brief, weak tornado. For that reason, hail is likely to be hard to
come by with weak to marginal mid-level lapse rates. PWATs of 2-2.5"
are above the 99th percentile with 1-2" plausible at most locations.
LPMM suggest localized amount of 3+ inches are possible over
northeast Missouri, though thunderstorms are more progressive and
not necessarily oriented to support long duration training. Gusty
winds are the primary threat. If severe weather develops, the best
potential will be 3PM-9PM.

Friday`s temperatures will span the 80s. The fall-like system
rotates southeastward through the region Saturday with northerly
flow at the back side of the exiting system. Cloud cover and
lingering showers will hold much of the area in the 70s. By
climatological standards, these temperatures run around the 5th
percentile with near-record min max (coolest highs) in the low 70s.
Low will be in the 60s to low-70s tonight and Friday night.

&&

.LONG TERM /SATURDAY THROUGH THURSDAY/...
Issued at 253 PM CDT Thu Jul 30 2026

Cooler than normal conditions are expected to continue through the
later half of the weekend as the upper level system slowly moves
eastward. There are subtle indications that an isolated showers
linger into Sunday. This will depend on how quickly this shortwave
joins a second shortwave north of the Great Lakes and is finally
ejected northeast. The upper level ridge axis begins to lean
eastward from Monday through midweek with gradual moderation to the
airmass. Below normal temperatures rise to near seasonal normals
through midweek. NBM blended guidance plots a smattering of low-end
PoPs across the southeast section of the CWA Monday and Tuesday,
though the spread of potential is uncertain toward the tail end of
the period with the progression of the upper level trough
determining the extent of precipitation potential through early week.

&&

.AVIATION /00Z TAFS THROUGH 06Z SATURDAY/...
Issued at 615 PM CDT Thu Jul 30 2026

Dry, VFR conditions prevail across the region at this hour, and
will remain in place through a majority of the night. A
developing convective system across central Nebraska will dive
southeast through the night, arriving in central Missouri around
sunrise on Friday. Most depictions of the system feature weak
thunderstorms at the worst by the time it arrives, hence the
PROB30 TSRA groups at KCOU and KJEF. As the decaying system
moves further east, confidence in thunderstorms is pretty low.
Lower CIGs will also accompany this activity, with the best
chance for MVFR to instances of IFR ceilings existing at KUIN
where the upper-level wave will be strongest.

After a period of more tranquil conditions at the terminals
through the late morning into the afternoon, convection will
reinvigorate in the vicinity of the upper-level wave and
threaten scattered thunderstorms through the late afternoon into
the evening from west to east. Gusty winds of 40-50kts are
possible with the strongest thunderstorms, though no confidence
exists on exact terminal impacts at this time. Convection
strength and coverage wanes with sunset and largely ends by 06Z
Saturday.


&&

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

&&

$$

SHORT TERM...Maples
LONG TERM...Maples
AVIATION...MRB