Old Jamestown, Missouri 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

324
FXUS63 KLSX 081938
AFDLSX

Area Forecast Discussion
National Weather Service St Louis MO
238 PM CDT Thu Oct 8 2026

.KEY MESSAGES...

- Near-record warmth and predominantly dry weather is forecast into
  early next week.

- The remnants of Tropical Cyclone Isaias bring slightly
  "cooler" temperatures Saturday and Sunday due to clouds, as
  well as chances of light rain in southeast Missouri and
  southwest Illinois.

&&

.SHORT TERM /THROUGH FRIDAY NIGHT/...
Issued at 232 PM CDT Thu Oct 8 2026

Another mostly clear night is forecast across the area, with
exception of parts of northeast Missouri and west-central
Illinois where an increase in midlevel clouds is expected. The
combination of a clear sky, light/variable winds, and seasonably
low dewpoints (~25th percentile) will promote favorable
conditions for radiational cooling across much of the area.
This is especially true across southeast Missouri into southwest
and south-central Illinois near the surface ridge axis.
Guidance for several days has had a distinct warm bias, and this
should continue tonight in those aforementioned areas. Lows in
the upper 40s to low 50s are forecast in these regions, with
readings moderating into the mid 50s to low 60s as you travel
northwestward.

All remains on track for unseasonably warm temperatures again on
Friday with the mid/upper level ridge amplifying across the
region and 850-hPa temperatures climbing back above +18C (~99th
percentile of climatology). Plenty of sunshine is also
expected, which will also help temperatures warm efficiently.
Highs are forecast to be mostly in the mid to upper 80s, though
a few spots may top out right near 90 degrees. Daily records
may be threatened at both St. Louis (89F/1938) and Columbia
(91F/1893), with Quincy likely coming up at least a few degrees
short (89F/1938).

Milder low temperatures are forecast Friday night as mid/upper level
clouds begin to increase after midnight in advance of the remnants
of Hurricane Isaias. If these clouds are a bit later than forecast
though, parts of southeast Missouri into south-central Illinois
again may be cooler than forecast. Southerly winds are expected to
be very light in those areas, particularly in river valleys where
winds tend to decouple easier.

&&

.LONG TERM /SATURDAY THROUGH THURSDAY/...
Issued at 232 PM CDT Thu Oct 8 2026

(Saturday - Sunday)

The remnants of Hurricane Isaias have shifted slightly east across
the Tennessee Valley this weekend. Consequently, the chances for a
widespread, soaking rainfall have dropped across our southeast
Missouri and southwest Illinois counties. The exact track of the low
looks to come down to internal dynamics, with individual vorticity
maxima rotating cyclonically around the broader midlevel
circulation. Predicting specific internal dynamics are near
impossible 24+ hours out, so there still may be a wobble
longitudinally. A farther west (east) track would increase
(decrease) the chances of light rain. As alluded to above, the
latest track from the National Hurricane Center is slightly east.
Probabilities for 0.25+" and 0.50+" have dropped significantly
on the latest LREF, now generally below 10-20%. In fact,
chances for as low as 0.10" have fallen as low as 15-30% even
along the southeastern CWA border. While some light rain still
seems likely in southeast Missouri and southwest Illinois, a
vast majority of the area will stay dry. There will be at least
some thickening mid/high level clouds moving northward on
Saturday. These clouds should "cool" temperatures this weekend
back into the low to mid 80s for most locations.


(Sunday Night - Monday Night)

After a brief lull in the near-record warmth due to cloud cover
associated with the remnants of Hurricane Isaias, it looks to return
on Monday. The air mass still appears to be more impressive compared
to Friday, with 500-hPa heights from the NAEFS above the 95th
percentile of climatology and 850-hPa temperatures close to +20C
(near record for the date). Surface winds also should turn more
out of the southwest, which is more favorable for downslope
winds off of the Ozark Plateau. Daily record high temperatures
certainly look to be in jeopardy, with even the monthly record
in St. Louis (94F on 10/11/1963) potentially under threat. Low
temperatures are also expected to be on the upswing due to
increasing surface winds and more cloud cover (especially Monday
night). Readings are forecast to only drop back into the 60s
each night for most locations.


(Tuesday - Next Thursday)

Forecast spread increases for mid week, mainly due to uncertainty
with the evolution of a cold front. This boundary is likely to move
through at least parts of the area on Tuesday before wavering back
north as a warm front later in the week. Confidence in temperatures
is quite low due to the wavering front and uncertainty in its
exact location. The inter-quartile range from the NBM is around
15 degrees each day, helping illustrate the high spread in high
temperatures. Chances of showers (and some thunderstorms) also
increases during this period as low-level moisture convergence
strengthens along with multiple midlevel impulses moving along
the crest of the ridge axis.

&&

.AVIATION /18Z TAFS THROUGH 00Z SATURDAY/...
Issued at 1212 PM CDT Thu Oct 8 2026

Dry and VFR conditions are expected through tonight. There is a
low threat of river valley fog, but temperatures will be warmer
tonight with some light southerly winds also possible. Winds
will increase closer to 10 mph out of the south by late Friday
morning.

&&

.CLIMATE...
Issued at 219 PM CDT Wed Oct 7 2026

Record high temperatures are possible between Friday 10/9 and Monday
10/12. Here are current records at each of our 3 official climate
stations:

                    KSTL            KCOU            KUIN
Friday 10/9       89/1938         91/1893         89/1938
Saturday 10/10    92/1963         92/1963         89/1963
Sunday 10/11      94/1963         89/1962         88/1962
Monday 10/12      90/2024         94/1899         88/1975

&&

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

&&

$$

SHORT TERM...Gosselin
LONG TERM...Gosselin
AVIATION...Gosselin
CLIMATE...Gosselin