St. Joseph, Missouri 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

675
FXUS63 KEAX 212329
AFDEAX

Area Forecast Discussion
National Weather Service Kansas City/Pleasant Hill MO
629 PM CDT Fri Aug 21 2026

...00z Aviation Update...

.KEY MESSAGES...

* Low confidence forecast tonight with scattered showers and
  thunderstorms across central into eastern Kansas.  Stronger storms
  would be capable of producing damaging winds and possibly large
  hail.

* Cooler and drier conditions Saturday into Sunday, with periodic
  storm chances returning as early as Sunday night.

&&

.DISCUSSION...
Issued at 241 PM CDT Fri Aug 21 2026

18Z sounding from OAX shows steep mid level lapse rates from 700-500
mb leading to elevated instability.  Dry layer below 600 mb leading
to reservoir of downdraft CAPE of 1000-1500 J/kg. Cluster of
storms that developed in north central Nebraska has somewhat
maintained their strength working to the southeast toward the
I-80 corridor. Low confidence forecast for tonight as back door
cold front associated with low pressure center near the Great
Lakes slides south. Instability is largely controlled by the
lifting level, but if we are able to get a near surface based
storm, there would be enough instability (3000-3500 J/kg) to
create the potential for large hail especially with 40-45 knots
of effective shear. If storms remain more elevated, the greatest
severe threat would be damaging winds owing to the dry air
below 600 mb.

Models offer a variety of solutions with these storms this evening.
It appears the atmosphere is at least weakly capped (cin 50-100
J/kg) across northwest Missouri, with an increasing cap farther
south.  It is unclear have long the storms would be able to maintain
themselves, but some solutions suggest storms trying to build
southeast through the evening hours along and west of the Missouri
River Valley.

Lee troughing across eastern Colorado is expected to become better
organized tonight into a weak low pressure center that develops in
western Kansas.  A weak low level jet extending from central
Oklahoma through central KS into western Nebraska is expected to
lead to strong theate-e advection and additional thunderstorm
development tonight. These storms are expected to move southeast
overnight in northwest flow aloft building into central and
eastern KS overnight. It appears these storms may primarily
remain west of the forecast area, but eastern KS into far
western Missouri may get brushed by any activity with the
potential of large hail and damaging winds with any storm that
is able to sustain itself this far east.

Cooler and drier conditions are expected to build south across the
region Saturday and continue into Sunday as Canadian high pressure
noses into the region.  Long standing ridge across the western US
has periodic ridge riders that may lead to periodic chances of
showers and thunderstorms.  The first wave moves through the region
Sunday night, with additional storms possible Wednesday morning.

&&

.AVIATION /00Z TAFS THROUGH 00Z SUNDAY/...
Issued at 624 PM CDT Fri Aug 21 2026

Have gone with VFR conditions across the sites, but not without
a small asterisk. Before that though, conditions should largely
see light to variable winds this evening and into the overnight
before gradually settling out of the NE. Even so, winds to
remain on the lighter side under 10 mph. Periods cloud cover
through much of the period, but should reside around / above
15 kft. Now for the asterisk... there should be convective
activity west of the area through central into eastern Kansas
late overnight tonight and Saturday morning. Guidance keeps
majority of activity west of the terminals, but a few do suggest
scattered shower/storm potential. Confidence was not great
enough to put any mentions in at this time, but trends will
continue to be monitored for any needed amendments or addition
to 06z issuance.

&&

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

&&

$$

DISCUSSION...BT
SHORT TERM...
LONG TERM...
AVIATION...Curtis