St. Joseph, Missouri 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

843
FXUS63 KEAX 121704
AFDEAX

Area Forecast Discussion
National Weather Service Kansas City/Pleasant Hill MO
1204 PM CDT Wed Aug 12 2026

.KEY MESSAGES...

- Potential for morning thunderstorms across northern Missouri.
  If the storms are able to develop, strong storms would be
  capable of producing damaging winds and possibly hail.

- Hot and humid conditions are expected to continue late this
  week into the weekend. An excessive heat warning is in effect
  along and south of the Missouri River, with a heat advisory
  highway 36 and south. The heat advisory is in effect through
  Thursday evening and the Excessive Heat Warning runs through
  Friday evening.

&&

.DISCUSSION...
Issued at 320 AM CDT Wed Aug 12 2026

MCS across north central Nebraska as of 08Z is expected to build
east with an ever so slight south drift as the 850-300 mb mean wind
is largely west to east. Atmosphere ahead of this complex is primed
with nearly 4000 J/kg of MU CAPE and 35 -45 knots of effective
shear. The focus of the MCS is largely expected to remain north
across Iowa; however, storms developing along the outflow could
build into northern Missouri this morning.  Forecast soundings
across northern Missouri show a dry sub cloud layer leading to 1500-
1700 J/kg of downdraft CAPE suggesting damaging wind potential with
anything that is able to develop this far south.

Behind the departing MCS, expect atmosphere to recover with
southwest flow feeding into the region from Texas. With that said,
some hi-res CAMs suggest that outflow may linger across the region
potentially leading to cooler high temperatures than in the forecast
if this becomes reality. For now, have forecast highs returning into
the 90s with dew points in the 70s leading to heat indices of 105-
110 F across much the area.  At this point, heat headlines look
reasonable.

Low pressure across western KS is expected to promote easterly winds
across Nebraska.  The upslope along with short wave ejecting from
the desert southwest is expected to lead to lat afternoon
thunderstorm development across the western High Plains.  Models are
offering a variety of solutions on how these storms evolve, but
northern Missouri could get clipped by any complex that develops.
The severity would be dependent on how well the atmosphere is able
to recover throughout the day today.  The convection may also push
stationary boundary across central Iowa southward, potentially as
far as northern Missouri.

Low level jet is expected to develop again from eastern Texas to
western/ central Missouri.  While the dry air just above the surface
would limit convective potential, the low level jet will keep the
atmosphere quasi-mixed keeping overnight lows mild once again.  This
will set the stage for another mild day Thursday into Friday south
of the boundary as the long standing low pressure across the western
High Plains slowly drifts north. As the low builds north, it is
expected to strengthen, and the associated cold front could be the
focus of showers and thunderstorms with the potential for more
seasonal temperatures returning to the region early next week.

&&

.AVIATION /18Z TAFS THROUGH 18Z THURSDAY/...
Issued at 1201 PM CDT Wed Aug 12 2026

Generally VFR thru the period with low potential for MVFR CIGs
across northern MO early Thursday morning. Winds KMKC and
northward expected to fluctuate late afternoon/early
evening...opted for few hours of VRB as winds move from SW to N
to E before settling back out of the SSE later tonight.

&&

.EAX WATCHES/WARNINGS/ADVISORIES...
MO...Extreme Heat Warning until 8 PM CDT Friday for MOZ028>033-
     037>040-043>046-053-054.
     Heat Advisory until 8 PM CDT Thursday for MOZ011>017-020>025.
KS...Extreme Heat Warning until 8 PM CDT Friday for KSZ025-057-060-
     103>105.
     Heat Advisory until 8 PM CDT Thursday for KSZ102.

&&

$$

DISCUSSION...BT
AVIATION...Macko