Old Jamestown, Missouri 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

066
FXUS63 KLSX 111058
AFDLSX

Area Forecast Discussion
National Weather Service St Louis MO
558 AM CDT Sun Oct 11 2026

.KEY MESSAGES...

- Near-record warmth is expected through Tuesday.

- A quasi-stationary front brings multiple chances for showers
  and thunderstorms Tuesday night through Thursday.

- A stronger cold front brings cooler and drier weather for the
  weekend.

&&

.SHORT TERM /THROUGH MONDAY/...
Issued at 248 AM CDT Sun Oct 11 2026

Above normal temperatures are expected today, warming even further
for the start of the work week. High temperatures will approach
record levels Monday.

IR satellite shows the remnants of Isaias rotating northeast
over Tennessee and into Kentucky early this morning. The western
edge of the cirrus shield runs near the Mississippi River with
latest imagery showing more aggressive eastward progression
since 03z. Skies were mainly clear westward over the remainder
of Missouri and far west-central Illinois. Light winds and dry
conditions will allow efficient cooling tonight, especially
where skies remain clear. How quickly the cirrus moves east is
the lingering question, as RAP soundings show gradual drying
with moisture centered around 300mb. Where skies clear, river
steam fog is likely with adjacent roadways briefly, and locally
impacted by lower visibility (around 1SM) in short distances.
Much of it erodes by 13z this morning.

An upper level ridge begins to amplify ahead of a digging western
trough today into Monday. Light surface flow begins to turn west to
southwest later today with modest warm air advection. Warm air
advection intensifies behind a warm front Sunday night into Monday
as the ridge becomes stacked over the northern Gulf and strengthens
to around 594dam. Strong, southwesterly 850mb flow draws warm air
(15-20C) into the Plains that is 2-2.5 standard deviations above
normal (near the 100th percentile), then spreads eastward into the
Mid-Mississippi Valley. RAP soundings show deep mixing at or just
above the 850mb level with higher moisture remaining west until
Tuesday. Considering the dry antecedent conditions and deep mixing,
temperatures should respond quickly during the afternoon periods
today and especially Monday afternoon with near-record highs (see
climate section).

Highs today will be in the mid-80s to low-90s and tonight`s lows
will be in the 60s. Monday`s highs climb into the low to mid-90s
with Monday night`s lows only in the mid-60s to low-70s.

&&

.LONG TERM /MONDAY NIGHT THROUGH SATURDAY/...
Issued at 248 AM CDT Sun Oct 11 2026

Near-record highs are expected once again Tuesday, all ahead of an
approaching cold front that is expected to stall in the region. The
stalled front becomes the focus for active weather through midweek,
until a stronger cold front brings much cooler and drier conditions
by the end of the week.

The two primary features to watch are the ridge over the northern
Gulf and the western trough. The Gulf ridge maintains its influence
over the Midwest Tuesday, as we await the arrival of a cold front to
the north. Latest trends continue to slow the cold front with LREF
surface temperature spreads of 3-4 degrees through Tuesday
afternoon. GFS MOS guidance is quite bullish and likely overdone
with temperatures well into the 90s and even touching 100 at KSTL,
especially with higher dewpoints (mid/upper 60s) drawn in from the
southwest. However, that`s not to say it won`t be near records, as
the lower resolution of the ECMWF ensembles paint low-90s across
much of the region. Highs will likely reach near records once again.

This pattern begins to break through midweek as surface high
pressure slides east across the northern CONUS Wednesday through
Friday. The front becomes sandwiched between the northern surface
high and ridging over the southeast CONUS. Meanwhile, the evolution
of the upper pattern is far less certain as long range global
guidance have two very different solutions. Both show a Canadian
trough tracking southeastward, which has polar origin. Where the two
diverge is how they handle the cutoff trough to the west. ECMWF
maintains the cutoff low before retrograding it westward later in
the week, while the GFS show the low consolidating with the Canadian
trough and phasing with the northern stream as is slingshots to the
northeast. LREF temperature spreads of around 10 degrees result from
this uncertainty in the pattern`s evolution. What looks somewhat
promising is the chance for measurable rainfall considering the
recently dry and warm stretch. Though global ensembles show a
large spread in amounts with episodic waves of scattered showers
and thunderstorms. PWATs are 3-4 standard deviations above
normal, running around 2 inches. Fortunately, the front is more
so quasi- stationary and wavers some as this all transpires. I`d
expect efficient rainfall production, though specific locations
with higher totals will adjust day-to-day until the front
clears the area.

By late week, a strengthening surface high aids to push the front
through with much cooler air filling in behind it. We may even see
temperatures dip slightly below normal next weekend with a
decrease in LREF IQR spreads (around 5-7 degrees), indicating
at least decent confidence in cooler, drier trends heading into
Friday through next weekend. Highs then looks to be 20-30
degrees cooler (50s/60s) by Saturday with mid-30s to low-40s
Saturday/Sunday mornings. This could be the first potential for
frost, especially for cooler, outlying locations.

&&

.AVIATION /06Z TAFS THROUGH 00Z TUESDAY/...
Issued at 547 AM CDT Sun Oct 11 2026

High clouds have cleared the terminals early this morning,
resulting in localized steam fog around KCPS and KSUS.
Visibility around the two sites will be highly variable until
sunrise, when it is expected to erode fairly rapidly.

Light and variable winds gradually increase and turn out of the
southwest through today. VFR conditions will persist thereafter.

&&

.CLIMATE...
Issued at 257 AM CDT Sun Oct 11 2026

Very warm temperatures are expected over the next several days.
This will challenge daily record highs and record warm lows on
multiple occasions. The daily records threatened are shown
below.

Record High Temperatures:

October 11:
KSTL: 94/1963
KCOU: 89/1962
KUIN: 88/1962

October 12:
KSTL: 89/1890
KCOU: 94/1899
KUIN: 90/2024

October 13:
KSTL: 90/1899
KCOU: 95/1899
KUIN: 87/1975

Record High Minimum Temperatures:

October 12:
KSTL: 70/1997
KCOU: 69/1928
KUIN: 70/1928

October 13:
KSTL: 69/2008
KCOU: 69/1899
KUIN: 65/1935

October 14:
KSTL: 70/1899
KCOU: 67/2017
KUIN: 67/1920

In addition, all time monthly record high temperatures are
within range of being broken. The following are the October
monthly high temperature records at each site:

October Record High:
KSTL: 94 most recently on Oct 1, 2019
KCOU: 96 on Oct 7, 1939
KUIN: 96 on Oct 7, 1939

&&

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

&&

$$

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