St. Joseph, Missouri 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

617
FXUS63 KEAX 162341
AFDEAX

Area Forecast Discussion
National Weather Service Kansas City/Pleasant Hill MO
641 PM CDT Wed Sep 16 2026

.KEY MESSAGES...

- Fog potential tonight into Thursday morning, mainly near and north
  of Highway 36

- Seasonally hot and humid conditions for areas around/south of Missouri
  River and I-70 through Friday. Including highs into the 90s
  and heat index values into the low 100s possible.

- Multiple rounds of showers and storms possible over the weekend.

- Cooler, more seasonable to seasonably cool temperatures begin
  to overspread the region later Sunday and into next week.
  Highs falling into the 70s.

&&

.SHORT TERM /THROUGH FRIDAY NIGHT/...
Issued at 317 PM CDT Wed Sep 16 2026

A tale of two regions for the forecast area today. Morning showers
and generic thunderstorm activity for much of the area near and
north of I-70 has largely subsided and given way to a northward
lifting warm front and clearing skies. As such, this yields starkly
different days from Northern Missouri to Central Missouri. Expect
highs underneath areas with lingering cloud cover to struggle to do
much more than the upper 70s to low 80s, while areas further south
will be dictated by just how much sunshine and mixing depth can be
achieved. Given the 850mb warm nose >20 deg C. Initial forecasts
suggested the ~90 deg F line to be around the east-west portions of
the Missouri River. Given recent trends and observations that is
more likely to be a tier of counties northward, regardless, cooler
north to warm to hot and humid as you work southward across the area
today.

Tonight, potential for additional showers and storms has tended to
trend northward among the short-term guidance suites. While the
surface front may not fully lift out of Missouri and into Iowa, it
should be enough to keep activity into Iowa. Storm chances into the
overnight will be driven predominantly by LLJ/isentropic ascent
overriding the surface/near-surface front. Even if some activity
clips the far northern portions of Missouri, the activity should be
on the more progressive side with a notable lack of above surface
boundary for storms to train along and migrating LLJ. Most recent
CAM runs result in initial convection around 06z near and east of
Des Moines along the I-80 corridor and drifting eastward through the
overnight. Did briefly consider lining up with DMX/DVN a new Flood
Watch for tonight, and while much of the area has seen
plentiful/saturating rainfall with confidence increasing in the
location, have opted against. Otherwise, potential for some fog in
the vicinity of the surface front and northward given moist low
levels and light to nil winds tonight and have added as much into
the forecast.

Thursday sees a surface high drop into the Northern Plains, which
will help retreat the surface boundary back southward. There is some
uncertainty in just how far south it will be able to retreat. The
850mb thermal ridge will remain overhead across the area, so the
importance of the surface boundary ties to cloud cover and mixing
depth potential. In general it will set up another day where
Northern Missouri will feel drastically different than areas near
and south of I-70. Northern areas could also see a few showers or
general thunder as weak isentropic lift continues as well, but in
similar fashion to today should weaken as the day progresses.
Concurrent, the large scale pattern begins to see a bit more change
as western CONUS mid-level cutoff low/trough begins to move more
inland and a shortwave disturbance lifts out of Sonora/Mexico.

The waffling surface boundary/warm front will see another northward
surge Friday as surface low develops and pushes off the Colorado
Front Range. By this point the Norther Plains surface high will have
pushed eastward and may keep shower/storm chances ongoing for NE
portions of the CWA. This will also again potentially yield a
dramatic difference in conditions across the CWA itself. A more
active overall pattern for the area then prevails into the
weekend...

&&

.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
Issued at 317 PM CDT Wed Sep 16 2026

We could see another opportunity for storms over the weekend as the
upper-level trough in the Pacific Northwest tries to push into our
area but it will be fighting the upper-level ridge over the SE US. A
surface low over the Central Plains will bring another cold front to
our area but with the battle between the upper-level trough and
ridge, that front will potentially stall out over our forecast area
bringing the potential for multiple rounds of rain Saturday and
Sunday night. The ridge begins to flatten out early next week and
there is high confidence the cold front will move off to the SE on
Monday with the 25th to 75th percentile ensemble spread indicating
high temperatures in the 70s.

&&

.AVIATION /00Z TAFS THROUGH 00Z FRIDAY/...
Issued at 634 PM CDT Wed Sep 16 2026

For the metro terminals, looking ahead at quiet VFR conditions
through the TAF period. A cold front will meander south overnight,
gradually shifting light winds from southerly to northwesterly, but
precipitation and low cigs will remain well north of the area so
little impact is expected. At KSTJ, fog looks increasingly
likely around sunrise, particularly between 12-14z. Could see
VIS below airport minimums (as low as 1/2SM) before conditions
begin to improve around 14z.

&&

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

&&

$$

SHORT TERM...Curtis
LONG TERM...IPC
AVIATION...Shaw