Old Jamestown, Missouri 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

870
FXUS63 KLSX 100439
AFDLSX

Area Forecast Discussion
National Weather Service St Louis MO
1039 PM CST Mon Nov 9 2026

.KEY MESSAGES...

- Above average temperatures through midweek with cooler, near-
  normal temperatures returning for the second half of the week.

- Isolated to scattered showers are possible (30-50% chance) on
  Wednesday, mainly along and east of the Mississippi River.

&&

.SHORT TERM /THROUGH TUESDAY NIGHT/...
Issued at 1221 PM CST Mon Nov 9 2026

The upper-level ridge is expected to gradually degrade as it is
nudged eastward by a shortwave trough. This will revert much of
the region back to a zonal flow regime as a surface cold front
sinks into far northern Missouri overnight tonight. As this
boundary is expected to stall and drift no further south than
the I-70 corridor, conditions for the vast majority of the area
will likely be very similar to those noted today with high
temperatures in the upper 60s and even low 70s. On the other
hand (or side of the cold front, if you will), temperatures are
more likely to peak in the mid 60s. Confidence is high (>95%) in
maximum temperatures above 60F across the entire forecast area
on Tuesday with many locations anticipated to exceed normal high
temperatures by 5-10 degF, even on the cool side of the
boundary.

Dry low/mid level conditions should continue to impede cloud
cover, even in the vicinity of the surface front. Radiational
cooling overnight could reintroduce some patchy fog, primarily
in river valleys, but the shallower temperature gradient should
limit any widespread development.

&&

.LONG TERM /WEDNESDAY THROUGH MONDAY/...
Issued at 1221 PM CST Mon Nov 9 2026

An Alberta Clipper system will surge southeastward on Wednesday,
ushering the stalled boundary through the region as a cold
front. A downward trend in the likelihood and coverage of
precipitation across eastern MO/western IL has been noted in the
guidance. This is likely a consequence of several factors,
including poor low-/mid-level moisture return given deep layer
westerly flow in advance of this system as well as the
timing/trajectory of the cyclone. Although isolated/scattered
showers cannot be ruled out, they do seem to be more highly
favored to the north and east. As such, PoPs were lowered
slightly...now roughly 30-50% along and east of the Mississippi
River and 15-30% to the west.

Behind this system, cooler temperatures will spread across the
Midwest behind this system while a longwave trough deepens over
the eastern third of the CONUS. As northwesterly flow settles in
aloft and the offset longwave ingests various shortwaves, much
cooler temperatures (highs in the 40s/low 50s and lows in the
mid-20s to mid-30s) will infiltrate the region with continued,
low-end potential for occasional light showers/drizzle late week.
Not too dissimilar to Wednesday, these precipitation chances
are greatest over the eastern portions of the forecast area
where greater upper-level support exists. At the very least,the
end of the work week looks cloudier than it started.

Though specifics on the timing and extent are yet to be fully
understood, another warm-up appears in store sometime this
weekend into early next week with height rises well-agreed upon
in ensemble clusters. Ensemble probabilities of high
temperatures greater than 60F increase from 25-45% on Sunday to
60-75% by Wednesday. While signs do seem to point to another
stretch of above normal temperatures, it`s not fully clear when
exactly these conditions will take root.

&&

.AVIATION /00Z TAFS THROUGH 06Z WEDNESDAY/...
Issued at 1038 PM CST Mon Nov 9 2026

As has been the case the last several days, the primary concern this
TAF period will be the development of river valley fog. Conditions
are not expected to be as favorable for fog as previous nights, but
at least some impacts are forecast at KSUS, KCPS, and KJEF early
Tuesday morning. Fog will dissipate through around 13 or 14z.
Otherwise, VFR flight conditions and light winds will prevail.

&&

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

&&

$$

SHORT TERM...WFO EAX
LONG TERM...WFO EAX
AVIATION...Pfahler