St. Joseph, Missouri 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

258
FXUS63 KEAX 220548
AFDEAX

Area Forecast Discussion
National Weather Service Kansas City/Pleasant Hill MO
1248 AM CDT Tue Sep 22 2026

.KEY MESSAGES...

- Fog and drizzle possible again this evening / tonight and into
  Tuesday morning. Best chances as you work north of Missouri
  River.

- Fall-like temperatures through the week.

- Rain chances begin to return late week, best chances western
  Missouri into Kansas

&&

.DISCUSSION...
Issued at 124 PM CDT Mon Sep 21 2026

Predominantly overcast skies prevailed across the area thus far
today, including pockets of lingering fog and drizzle to light rain.
By early afternoon, visibilities have improved to greater than 6
miles in most locations and stratus has begun to go more cellular in
nature. This is especially so in areas where higher level cloud
cover has understandably been non-existent or clearing out. Of
casual note, areas where mixing has been more robust, tending to be
south of I-70, have noted the potential within CAM soundings for
weak instability underneath the inversion to develop which could
lead to some very weakly convective light rain / showers. This
potential has most recently begun to be seen on KEAX radar along to
just on the SGF side of the CWA border, including around and east of
Clinton and south of Sedalia. Given that, do expect to see some
additional activity south of I-70 where more robust cellular action
is noted on visible satellite. Would not do much more than getting
the ground wet or ticking off up to a couple or few hundredths of an
inch of rain.

Deterministic and ensemble synoptic scale guidance have shown little
notable changes with recent runs. There remains fair to good
agreement on the general evolution of the synoptic pattern through
late week. This includes a weakly closed to open mid-level wave
drifting eastward across the Northern Plains today and Tuesday,
gradually developing into a messy Rex Block-like pattern, and
finally a closed low over and off the East Coast by late week into
next weekend. And on its heels will be ridging working back into the
central CONUS, but looks to struggle to make too much direct
progress over the area given the East Coast blockages. All the
while, a large surface high centered over the northern Great Lakes
into southern Ontario.

What does that all mean for the immediate area? Temperature wise, it
results in pretty persistent fall-like temperatures as NE to E
surface/near-surface flow prevails throughout the week. This results
in highs in the 60s/70s and lows generally in the upper 40s to 50s.
Coolest lows tending to be mid-week when cloud cover should be least
prevalent. Cloud cover and precipitation wise, yields lingering
periods of stratus and drizzle to light rain chances through Tuesday
with best chances over northern areas closer to the passing mid-
level wave. Followed by a dry mid-week as mid-level height rises,
the aforementioned ridging, slides into the central CONUS. Late week
is where the most uncertainty resides as the degree and position of
the blocking pattern over the East Coast will dictate how far east
precipitation chances creep and how quickly the area may see warming
temperatures. For now, not much change from previous forecast cycle
with the prevailing consensus keeping the mid-level ridge axis just
to the west of the area and embedded shortwaves rounding the ridge
into Nebraska/Iowa. Within the gridded forecast, this yields 20 to
40 percent PoPs beginning to creep into NW/W Missouri and NE Kansas
Thursday afternoon and evening and creeping eastward through Friday.
Takeaway being chances increase as you work toward W/NW Missouri and
into Kansas. Similar may occur into the weekend with deterministic
guidance showing additional shortwaves within the flow, possibly
attempting to flatten the ridge some. Understandably, aside from
PoPs, this also results in the most uncertainty in temperatures with
NBM spreads increasing to the 8 to 12 deg F range Saturday.

Regardless of all of the above, hope most are able to enjoy a
stretch of cooler temperatures after the stretch of late
summer/early fall heat.

&&

.AVIATION /06Z TAFS THROUGH 06Z WEDNESDAY/...
Issued at 1247 AM CDT Tue Sep 22 2026

Ceilings are currently MVFR but are expected to fall to IFR within
the next few hours around 9Z. Ceilings and visibility may drop to
LIFR before sunrise with the chance for patchy fog. Conditions are
expected to improve around 15Z, with P6SM visibility and MVFR
ceilings. Winds through the period are light out of the north
shifting to ENE around sunset Tuesday.

&&

.EAX WATCHES/WARNINGS/ADVISORIES...
MO...None.
KS...None.

&&

$$

DISCUSSION...Curtis
AVIATION...IPC