Old Jamestown, Missouri 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

676
FXUS63 KLSX 072308
AFDLSX

Area Forecast Discussion
National Weather Service St Louis MO
608 PM CDT Wed Oct 7 2026

.KEY MESSAGES...

- Dry weather with unseasonably warm temperatures are forecast
  through early next week.

- The remnants of Tropical Cyclone Isaias may bring (beneficial) rain
  to parts of southeast Missouri and southwest Illinois this
  weekend, but there remains a lot of uncertainty with its
  track.

&&

.SHORT TERM /THROUGH FRIDAY/...
Issued at 219 PM CDT Wed Oct 7 2026

The latest surface analysis shows a weak "cold" front moving
across northeast Missouri and west-central Illinois early this
afternoon. The term "cold" though is relative, as the air mass
behind it is not much cooler. Temperatures at 850 hPa Thursday
afternoon are only expected to be about 1C cooler than this
afternoon. Mixing tomorrow also does not look as deep as today
(closer to 850 hPa vs. 800 hPa). Therefore, highs should be
about 2-5F cooler on Thursday. However, those readings would
still be about 10 degrees above normal for the date. Lows both
tonight and Thursday night will also be a bit on the mild side,
but not as warm relative to normal due to light winds and a
mostly clear sky. Temperatures both nights are forecast to drop
into the 50s for most locations.

&&

.LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
Issued at 219 PM CDT Wed Oct 7 2026

(Friday - Friday Night)

The anomalous mid/upper level ridge flexes back northward on Friday,
with 850-hPa temperatures also climbing back toward +18C (>95th
percentile of climatology). High temperatures are therefore expected
to rebound right back into the mid to upper 80s, with some spots
potentially hitting the 90 degree mark. Daily record highs at both
St. Louis and Columbia may be threatened. Please see the CLIMATE
section below for more details. Some minor negating factors though
include winds more out of the south vs. southwest (not as much of a
downslope component, especially for St. Louis) and the potential at
least for some mid/high level cloud cover. The overall moderation
trend with respect to nighttime lows also is expected to continue,
mainly due to an increase in southerly flow at the surface. Low
temperatures Friday night are only expected to fall back into the
low to mid 60s (~10-12F above normal).


(Saturday - Sunday)

We continue to watch the track of Tropical Cyclone Isaias and its
path northward this weekend. The latest track from the National
Hurricane Center brings the center through west-central
Tennessee/western Kentucky. The edge of the 5-day cone is farther to
the west however. If the remnants of Isaias are more toward that
western edge, the chances for (beneficial) rain would increase
sharply across parts of southeast Missouri and southwest Illinois.
LREF probabilities for at least 1" of rain are in the 10-15% range,
though have been trending upward as the overall spread in both
the timing and the track have been on the downswing. We may know a
lot more about the track and impacts (if any) in our area as there
is a pretty clear delineation between guidance that more rapidly
strengthens Isaias (more toward the east) vs. weaker solutions (more
toward the west). Regardless, at least some modest "cooling" during
the daytime hours would be likely due to an increase in mid/high
level clouds on the outskirts of any remnants of Isaias, as well as
some weak to moderate low-level cold air advection from the
southeast. The spread in high temperatures each day is highest where
rain is more likely to impact the region. Across parts of southeast
Missouri and southwest Illinois, the inter-quartile range on the NBM
is closer to 10 degrees, but drops closer to 5 degrees for the
northwestern CWA.


(Sunday Night - Next Wednesday)

There is high confidence that unseasonably warm temperatures will
continue into early next week. In fact, another run at daily records
is quite possible areawide on Monday afternoon. Monday actually
probably has the best potential at low 90s, with GEFS/EPS mean 850-
hPa temperatures approaching +20C (~99th percentile). Winds also
should veer more to the southwest ahead of an approaching cold
front, which would promote downsloping. There is of course though
some uncertainty with the frontal timing given that this is 5 days
out, but the most likely window appears to be Monday night at this
point in time. Cooler temperatures are expected behind this front,
though readings likely will remain above normal for mid October.
Even the 25th percentile of the NBM is right near normal, so ~75% of
members have at or above normal values.

&&

.AVIATION /00Z TAFS THROUGH 06Z FRIDAY/...
Issued at 600 PM CDT Wed Oct 7 2026

Winds will become light and variable this evening and continue
through the TAF period. Confidence in fog development tonight is
still too low for mention in the TAFs, but will keep monitoring
tonight.

&&

.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...Jaja
CLIMATE...Gosselin