St. Joseph, Missouri 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

100
FXUS63 KEAX 192345
AFDEAX

Area Forecast Discussion
National Weather Service Kansas City/Pleasant Hill MO
645 PM CDT Wed Aug 19 2026

.KEY MESSAGES...

* Isolated to scattered storms possibly this afternoon into the
  evening hours. Best chances for storms are along and north of
  highway 36, though evolution remains somewhat unclear.

* Patchy fog possible tonight in areas that see rainfall this
  evening.

* Near seasonal temperatures expected late this week into the
  weekend, but could see periodic chances of storms as waves
  pass through in northwest flow aloft.

&&

.DISCUSSION...
Issued at 223 PM CDT Wed Aug 19 2026

Complicated near term forecast with a cluster of storms across
eastern Nebraska diving southeast.  These storms have developed an
MCV, which may keep the trajectory southeast; however, 850-300 mb
mean wind is more west to east, and complex may try to develop
farther east with time.  Have started to see signs of development
along outflow- convergence boundary in the vicinity of highway 34.
This activity should largely move west to east following the
mean flow and the CAP gradient/ but may try to build south with
time as the boundary moves south. Along the boundary, there is
the potential for a funnel cloud or two, especially if storms
are able to root along the slow moving boundary.

Abundant cloud cover has limited instability across much of Missouri
today, but partial clearing after 1730Z may lead to increasing
instability along and north of highway 36.  Elevated CAPE values of
1500-2000 J/kg and effective shear of 40-45 knots may still create a
severe weather threat with large hail and damaging winds being the
primary threats across northern Missouri through the 20-02Z time
frame.  Storm movement should be sufficient (25-35 knots) that flash
flooding threat should be fairly limited with the exception of slow
moving storms that are tied to the outflow boundary.

With all the said, if storms are able to develop in what looks to be
a weakly capped environment across eastern Kansas, storms may
try to build farther south and east though instability may be
fairly limited.

Weak surface ridge across southern Minnesota is expected to build
south towards southern Iowa overnight.  This will lead to light
northeast winds and the potential for fog to develop in areas that
see rain this evening. Greatest likelihood will be across
northern Missouri.

Weak flow may limit mixing tomorrow morning and patchy fog may
linger a bit longer than one might think. Surface ridge is gradually
expected to shift east tomorrow and with more clearing, expect
temperatures to warm closer to seasonal norms for this time of year.

Shortwave dropping down in northwest flow could lead to additional
thunderstorms across the Upper Midwest on Friday.  Upper level ridge
across the western US strengthens this weekend, though periodic
ridge riders lead to periodic pops through the weekend.

&&

.AVIATION /00Z TAFS THROUGH 00Z FRIDAY/...
Issued at 645 PM CDT Wed Aug 19 2026

A boundary from storms to the north is progressing through the
terminals which may bring some northerly gusts through over the
next couple of hours. Winds then become light and variable
through the overnight as MVFR CIGs settle in. BR/FG is expected
to develop during the overnight with relatively minor VIS
impacts across the area although CIGs are expected to sink to
IFR levels. Should CIGs not lower or sky coverage remain less
dense, VIS impacts may be more significant. VIS impacts across
STJ where more RA/TSRA occurred is expected to be lower. CIGs
and VIS improve after sunrise tomorrow with SCT MVFR CIGs
expected after mid morning. Winds remain light and variable
through most of the period.

&&

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

&&

$$

DISCUSSION...BT
AVIATION...Pesel