Old Jamestown, Missouri 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

988
FXUS63 KLSX 201930
AFDLSX

Area Forecast Discussion
National Weather Service St Louis MO
230 PM CDT Tue Oct 20 2026

.KEY MESSAGES...

- Dry weather along with above normal temperatures are expected
  to continue through the week into this weekend.

&&

.SHORT TERM /THROUGH THURSDAY/...
Issued at 226 PM CDT Tue Oct 20 2026

There`s little change in the forecast this afternoon.  An upper
level ridge remains over the central CONUS sandwiched between
troughs over both coasts.  A sprawling surface ridge remains in
control of the weather across the Great Lakes, Midwest, and Ohio
Valley as well. The upper level omega block and surface ridge will
remain in place through the short-term which will continue our
stretch of uneventful weather. Temperatures across the forecast area
are 3-5 degrees warmer today than yesterday, and it should continue
to warm slowly tomorrow and Thursday due to good daytime insolation
and light south to southeasterly flow.

&&

.LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/...
Issued at 226 PM CDT Tue Oct 20 2026

The omega block begins shifting east Thursday night, and the western
trough moves over the Rockies by Friday evening.  Medium range
deterministic guidance shows the trough fracturing, and the
resulting northern stream short wave moves across southern Canada
and the northern Great Plains.  The cold front attached to the
surface reflection of the wave drifts through the Upper Midwest
Saturday, and slows down to become nearly stationary across southern
Minnesota, Michigan, and nothwest Iowa on Sunday.  Models then show
another upper level wave diving through southwest Canada Sunday
night and into the northern Plains Monday where it phases with the
left over southern stream energy.  The combined positively tilted
trough then digs southeast, which finally pushes the cold front
through the Mid Mississippi Valley on Tuesday.  All this adds up to
continuing dry and warm weather for the Mid Mississippi Valley at
least through the weekend south of the cold front, and probably for
Monday and Tuesday as well.  The LREF continues to show variance in
the strength and position of the northern stream trough
Friday/Saturday, and the combined trough Sunday through Tuesday. The
variance mostly affects locations well north of our forecast area
through the weekend.  Temperature IQRs in the LREF are only 3-4
degrees in our area through Sunday.  However, the IQR increases to
10 degrees across northeast Missouri and west central Illinois as
the combined trough and cold front approach the area on Monday. The
IQR spreads out to 10-15 degrees across the rest of the area on
Tuesday as the members of the LREF attempt to push the front
through.  The deterministic NBM shows highs dropping from the mid
and upper 70s on Sunday and Monday into the 60s Tuesday with the
front. However, confidence in the forecast remains low early next
week as guidance continues to have some issues with the placement of
the front.

&&

.AVIATION /18Z TAFS THROUGH 00Z THURSDAY/...
Issued at 1204 PM CDT Tue Oct 20 2026

VFR flight conditions and light/variable winds are expected to
continue through the period. Temperatures will be a few degrees
warmer on Wednesday morning which should lead to less fog than
either Monday or this morning. However, localized shallow fog is
still a possibility in river vallies and other low/sheltered
spots.

&&

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

&&

$$

SHORT TERM...Carney
LONG TERM...Carney
AVIATION...Carney