Old Jamestown, Missouri 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

734
FXUS63 KLSX 271945
AFDLSX

Area Forecast Discussion
National Weather Service St Louis MO
245 PM CDT Tue Oct 27 2026

.KEY MESSAGES...

- Warm and dry conditions continue through at least Thursday and for
  most locations Friday.

- Rain chances begin to nudge in from the north as soon as
  Friday. Rain chances then increase over the weekend into
  early next week.

&&

.SHORT TERM /THROUGH WEDNESDAY/...
Issued at 244 PM CDT Tue Oct 27 2026

Benign conditions continue through midweek with temperatures
moderating back to near 80 degrees Wednesday.

An upper level shortwave trough is passing over the Mississippi
Valley today, resulting in a steady stream of broken to overcast
high clouds. A majority of the forecast area has failed to reach 70
degrees by noon with a slow, gradual climb into the low to mid-70s
before cooling this evening.

As today`s shortwave departs northeast tonight, mid/upper southwest
flow turns westerly and scours out saturation within the 700-300MB
layer. Upper level 500MB vort charts show additional weak vort lobes
embedded within the west-southwestwerly flow over the Mid-
Mississippi Valley. However, surface/mid-level ridging that extends
from the Mid-Atlantic, westward through the southern Plains,
maintains dry conditions with modest mid-level warming. Mostly clear
skies and mid-level temperature moderation will aid in returning
surface temperatures to near 80 degrees Wednesday afternoon. These
trends continue into Wednesday night with lows roughly 3-5 degrees
warmer than Tuesday night, ranging from the low-50s to near 60
degrees.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH TUESDAY/...
Issued at 244 PM CDT Tue Oct 27 2026

Mild and dry conditions will slowly give way to cooler, more
seasonable temperatures over the weekend into next week. Rain chances
remain low through Thursday with chances increasing over parts of
the region as soon as Friday. More widespread potential arrives over
the weekend into next week.

A more vigorous upper level shortwave and surface low moves west to
east over the southern Canadian Provinces through the midweek period.
This system will send a cold front southeastward through the Upper
Midwest Thursday. Despite the breakdown in the upper level ridge,
surface/mid-level ridging over the eastern U.S. maintains its
influence with southerly flow encountering the slowing front near
the MO/IA border. The stalling front results in some spread with
respect to cloud cover, low rain chances (<20 percent), and
consequently high temperatures. What spread does exist is not
terribly large (5 degrees) and within a narrow corridor across the
far northern sections of the CWA. Aside from KUIN, Thursday`s NBM
temperatures have quietly inched within 5 degrees of record highs
(86 at KSTL and KCOU). Forecast highs (low-80s) give some pause with
recent bias correction leaning a little too warm. Even at the 80
degree threshold, HREF probabilities range 30-45 percent along/south
of I-70. Records are unlikely in this setup, but warm temperatures
and their persistence through late October remain notable.

As we progress from Friday into the weekend, rain chances gradually
increase, but model spread follow suit. Global guidance differs in
the a number of regional/small scale features, such as the eastern
ridge, speed/strength of a southern Plains surface low, and timing.
Higher moisture initially pools along and south of the stalled
boundary late Thursday into early Friday vorticity advecting out of
the southern Plains and hugging the northern side of the upper
ridge. Rain chances (30 percent) extend as far south as I-70 and
increase to near 70 percent over far northeast MO. Aerial extent of
the PoPs may be too broad as model sounding quickly dry further
south with most location remaining dry and mild.

A broad trough digs into the southwest CONUS over the weekend into
early next week, which ejects additional disturbances northeastward
into the central U.S. Rain chance continue to increase next weekend
into early next week. The best chances for widespread, soaking rain
favor late Sunday and early next week. Cooler, near normal
temperatures are favored to return.

&&

.AVIATION /12Z TAFS THROUGH 18Z WEDNESDAY/...
Issued at 1157 AM CDT Tue Oct 27 2026

VFR conditions persist under broken high clouds this afternoon.
Clouds gradually clear tonight into Wednesday, accompanied by
light, southerly surface flow.

&&

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

&&

$$

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