Old Jamestown, Missouri 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

597
FXUS63 KLSX 301132
AFDLSX

Area Forecast Discussion
National Weather Service St Louis MO
632 AM CDT Fri Oct 30 2026

.KEY MESSAGES...

- Temperatures remain abnormally-warm through early next week.

- Showers and a few thunderstorms are expected at times through
  the weekend, mainly this morning and late Saturday into
  Sunday morning with plenty of dry time otherwise.

- Widespread, beneficial rainfall arrives next week.

&&

.SHORT TERM /THROUGH SATURDAY/...
Issued at 329 AM CDT Fri Oct 30 2026

Convection continues to percolate at this hour across northern
Missouri into west-central Illinois along a weak, stalled front
impinged by an equally-weak low-level jet centered in the
Plains. The thunderstorms are stalling where they form, leading
to locally- heavy rainfall. A few weaker showers extend south to
near the eastern I-70 corridor, but are more isolated and
further removed from any forcing. Aloft, weak ridging persists
but a longwave evident in mid-level water vapor imagery is
crawling north from Mexico into the southern Plains. The
presence of the front and resultant cloud cover and intermittent
convection will keep temperatures in check across northern
Missouri and west-central Illinois today. Further south, another
unseasonably-warm and largely dry day is in store. Short-range
guidance is in pretty fair agreement that sometime today, likely
in the afternoon, flow aloft gradually amplifies and becomes
more southwesterly ahead of the slow- moving trough from the
southern Plains. This change will result in increased rain
chances, mainly west of our forecast area, this afternoon and
evening. A few stray showers can`t be ruled out across central
and northeast Missouri associated with the diffluent flow aloft,
but most will stay dry into early Saturday.

By the morning hours of Halloween, weak, broad troughing aloft will
be overhead in the Mid-Mississippi Valley, promoting abundant cloud
cover that will inhibit temperatures noticeably compared to
previous days. Model soundings are quite stable and struggle to
saturate the low-levels, keeping a threat for any stronger
showers or thunderstorms at bay. Weak, nebulous isentropic
ascent is evident in most guidance, suggesting light rain
remains a threat for outdoor activities. That said, most
solutions suggest that what little ascent exists will maximize
late in the evening Saturday. While a completely-dry day is not
a guarantee, trick-or-treating won`t be a washout by any
standards and most areas will be largely dry until the ghosts
and goblins are inside for the night.

&&

.LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...
Issued at 329 AM CDT Fri Oct 30 2026

As the clocks roll back and the calendar turns forward to November,
the light rain associated with this initial weak wave tracks east
and exits the region early Sunday afternoon. Meanwhile, a deeply-
amplified trough comes onshore across the western CONUS. In between
these two waves, weak ridging aloft will promote a dry start to the
work week on Monday. The western wave makes quick eastward progress
and arrives in the Mid-Mississippi Valley by late Monday night,
according to a growing consensus of ensemble guidance. As it tracks
east, it will occlude, slow down, and draw copious Gulf moisture
poleward. As a result, precipitable water values are forecast above
the 99th climatological percentile across much of the region,
potentially setting records for early November. The strong forcing
and abundant moisture will all but certainly result in widespread,
beneficial rain for the region from very late Monday through at
least early Thursday. In this timeframe, there is an areawide 20-30%
chance for at least 1.00 inches of rain according to the NBM. The
highest totals (perhaps as high as 3.00 inches locally) appear to be
most likely across western Missouri where forcing and moisture
overlap is maximized in ensemble guidance.

Despite these favorable synoptic parameters, model soundings show
very limited instability and only marginal warm cloud depths for
more efficient rainfall. While I cannot rule out some instances of
heavier rain where multiple rounds impact the same place, that
should be the exception and not the rule in this event. As for a
severe thunderstorm risk, while shear parameters are understandably
more impressive with the strong wave, instability remains very
limited and jet-level dynamics are very unfavorable for large-scale
ascent. These factors greatly limit any strong convection, however
if more instability can be made available to this impressive shear
and forcing, we would have a much higher severe weather threat. That
scenario is currently highly unlikely.

Depending on the speed and structure of this trough, we may see
intermittent rain linger through most of the week. By Friday, most
depictions of the wave show it east of the region. Unfortunately for
those looking for another decided taste of Fall, near to slightly-
above normal temperatures stick around in its wake. The airmass that
follows our widespread rain, while cooler, is not really Arctic in
nature by any stretch. The polar jet remains locked across southern
Canada for the foreseeable future, keeping shots of cold air from
making any intrusions south. By the end of the week, above-normal
temperatures and drier conditions appear favored yet again going
into mid-November.

&&

.AVIATION /12Z TAFS THROUGH 18Z SATURDAY/...
Issued at 629 AM CDT Fri Oct 30 2026

Showers and thunderstorms largely evaded the terminals
overnight, but KUIN has been under a near-constant threat for
convection since midnight. This will continue through the
morning as a front lifts north through the region, gradually
ending early this afternoon. Fog at KSUS is also rapidly
improving and should be all but dissipated by sunrise.

VFR conditions are forecast today, though fog may redevelop in
the river valleys tonight. Rain chances increase for Saturday
evening, just beyond the current TAF period. Rain intensity
will likely be light, making widespread impacts unlikely.

&&

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

&&

$$

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