Old Jamestown, Missouri 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

533
FXUS63 KLSX 101204
AFDLSX

Area Forecast Discussion
National Weather Service St Louis MO
604 AM CST Tue Nov 10 2026

.KEY MESSAGES...

- Above average temperatures will give way to the coldest
  temperatures we have seen so far this season during the second
  half of the week.

- Winds will occasionally gust 25 to 35 mph Wednesday afternoon
  and evening.

- The chance of rain has further decreased on Wednesday with
  mainly dry conditions now expected into the upcoming weekend.

&&

.SHORT TERM /THROUGH WEDNESDAY/...
Issued at 228 AM CST Tue Nov 10 2026

A slightly tighter surface pressure gradient in the vicinity of a
cold front reaching northeastern MO/west-central IL early this
morning has kept temperatures around 5 to 10 F warmer than 24 hours
ago. Therefore, conditions will not be as favorable for prolific
river valley fog formation, but patchy (mainly radiation) fog is
likely through sunrise. The aforementioned cold front, remaining
devoid of precipitation and even clouds, will stall near the I-70
corridor today, but high temperatures CWA will again reach the upper
60s to mid-70s F with full insolation and negligible CAA north of
the front.

On Wednesday, an Alberta Clipper with an amplifying upper-level
shortwave trough will support a deepening surface cyclone tracking
eastward across the Midwest and a trailing cold front passing
through the CWA. The majority of precipitation will remain north of
the cyclone track well north of the CWA. Additional scattered
showers and thunderstorms are expected to develop along the cold
front as modest moisture and lapse rates increase during the
afternoon and evening, but a trend toward a quicker frontal passage
in latest model guidance makes it increasingly uncertain if this
development will occur in the CWA. For example, REFS probabilities
of measurable rainfall are less than 10 percent and much higher just
east of the CWA. High temperatures will only be slightly cooler on
Wednesday than today, but are anticipated to begin falling during
the late afternoon as low-level CAA strengthens. This CAA, combined
with a tight pressure gradient in the vicinity of the surface
cyclone and seasonably deep boundary layer mixing will also support
occasional northwesterly wind gusts of 25 to 35 mph during afternoon
and evening.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...
Issued at 228 AM CST Tue Nov 10 2026

A longwave trough will amplify over the eastern CONUS by Thursday
establishing cyclonic flow across the Mid-Mississippi River Valley.
In this flow, multiple shortwave troughs/vorticity maxima will pass
overhead with the most potent shortwave trough passing on Thursday,
favoring sporadic light showers/sprinkles and/or drizzle along/east
of the Mississippi River among extensive stratocumulus. These clouds
and reinforced CAA will result in high temperatures in the 40s to
low-50s F on Thursday. However, the core of this seasonably cool
airmass will arrive Friday into Saturday with the coldest
temperatures we have seen so far this season including highs in the
40s F and lows in the 20s F aided by an accompanying nearby surface
anticyclone.

Global model guidance remains in agreement that mid-level heights
will begin rising over the Mid-Mississippi River Valley Saturday and
Sunday as the longwave trough in the eastern CONUS progresses
eastward. The NBM temperature distribution contains an underlying
warming trend into next week, but the interquartile range inflates
to around 10 F owing to differences in how quickly the surface
anticyclone retreats and low-level flow can become more southerly.
Another point of uncertainty is the potential for a weakening upper-
level shortwave trough to propagate across the Central Plains into
the Mid or Lower Mississippi River Valley late Sunday into Monday.
It is not yet clear if this feature would provide any rain to the
CWA with the highest probabilities of measurable rainfall from
global ensemble model guidance currently to the west and southwest
but there could at least be increased cloud cover.

&&

.AVIATION /12Z TAFS THROUGH 18Z WEDNESDAY/...
Issued at 602 AM CST Tue Nov 10 2026

Surface observations show little indications of river vally fog
this morning, as we`d seen develop over the past few mornings.
Given the absence of fog at this time, it is ulikely that it
will develop to the extent or magnitude it has in recent days.

VFR conditions are expected through the period.

&&

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

&&

$$

SHORT TERM...Pfahler
LONG TERM...Pfahler
AVIATION...Maples