St. Joseph, Missouri 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

902
FXUS63 KEAX 170456
AFDEAX

Area Forecast Discussion
National Weather Service Kansas City/Pleasant Hill MO
1156 PM CDT Thu Jul 16 2026

.KEY MESSAGES...

- Scattered showers and thunderstorms continue this afternoon
  and evening. Heavy downpours and gusty winds are anticipated,
  but severe weather is unlikely.

- Heat and humidity continue for the next several days.
  Temperatures and heat indices elevate through the weekend.

&&

.DISCUSSION...
Issued at 113 PM CDT Thu Jul 16 2026

Routine summer time programming continues for the region as high
temperatures today reach just about seasonal normals although
clouds and showers may slow the thermal ascent. A high over low
block continues to dominate the pattern over the central CONUS.
General southerly flow across the center of the country propels
a gradual, yet continual, increase in warm air and moisture
across the area.

Moisture transport is expected to expand northward today which when
coupled with increased warm air advection and diurnally enhanced
instability is likely to generate some air mass thunderstorms this
afternoon and evening. Some subtle vorticity advection aloft and
slight low level convergence will create just enough lift to
initiate convective development. Shear and mid level lapse rates are
fairly meager which curtails expectation of robust convection;
however, abnormally high PWAT values of 2-2.5 inches (>90
Percentile) do present an opportune environment for isolated heavy
rain showers. These downpours could result in rainfall rates of 1-2
inches per hour, with locally higher rate possible, which may lead
to some flash flooding and pooling from runoff. Storm motions are
also quite slow which may exacerbate impacts of heavy rainfall.
Storms are expected to be fairly pulse like with updrafts
developing and raining out fairly quickly. Unfortunately,
coverage of these storms is expected to be scattered so some may
receive all of the rain and some none. The good news is those
that receive the rain should experience a temporary cooldown
from the heat as highs reach the 90s for most and heat index
values reach 95-100 degrees. However, it is likely that post
storm conditions will feel more muggy and uncomfortable as
fresh rainfall evaporates. Rain chances through the rest of the
week look fairly marginal. There is some indication for
potential MCS activity mainly over the eastern parts of the
region early Friday morning; however, much of the activity is
expected to remain further east.

As the week rolls on ridging continues to dominate. The low over the
US/MEX border shrinks and meanders southward. This continues the
flow of warm air and moisture into the region steadily raising highs
into the mid to upper 90s by the weekend. Heat indices raise in kind
with expectations of around 100F by the weekend peaking around 100-
105F Monday. Current guidance suggests a 70+ percent chance of
exceeding 100F heat indicies and a 25 percent chances of advisory
level heat indicies on Sunday and Monday.

More of the same is expected in the extended forecast. Additional
rain chances return with a passing system early Tuesday morning, but
again, the main activity is expected to remain further east.
Extended guidance does show a potential for a break from the heat
mid next week as a dramatic push of cooler air is anticipated
to move southward from interior Canada. This looks to
significantly alter the pattern over the CONUS. However, with
such notable impact expected at this forecast scale, it is
important to account for potential deviations as those will
significantly affect the long term outlook.

&&

.AVIATION /06Z TAFS THROUGH 06Z SATURDAY/...
Issued at 1149 PM CDT Thu Jul 16 2026

Patchy fog is expected along and south of I-70 tonight into
early Friday morning. Scattered cumulus is expected to develop
after 15Z, with the potential for a few isolated storms driven
by diurnal heating after 18Z. These storms should weaken through
the evening, but increasing low level jet may keep a few storms
going through the evening hours.

&&

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

&&

$$

DISCUSSION...Pesel
AVIATION...BT