St. Joseph, Missouri 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

039
FXUS63 KEAX 152324
AFDEAX

Area Forecast Discussion
National Weather Service Kansas City/Pleasant Hill MO
624 PM CDT Sat Aug 15 2026

.KEY MESSAGES...

- Additional thunderstorm chances tonight into Sunday,
  generally along and north of the Missouri River, with strong
  winds and locally heavy rainfall being the primary threats.

- Some relief from the heat is expected heading into next week.

&&

.DISCUSSION...
Issued at 225 PM CDT Sat Aug 15 2026

Broad 500-hPa ridging remains across across the majority of the
CONUS, although the ridge has flattened out just a bit over the
previous 24 hours or so. Several shortwaves can be noted moving
through the upper-level flow, with the most notable ripple being
located over eastern NE, northeastern KS, northwestern MO, and
western IA. This shortwave is providing enough synoptic level
forcing to produce some light showers across northern MO early
this afternoon. While not super impactful, the showers, and
associated cloud cover, are working to keep temperatures from
climbing towards the previously forecasted mid-to-upper 90s. As
such, have capped afternoon high temperatures to the upper 80s
and low-90s north of the Missouri River. While dew points are in
the low-to-mid 70s, heat indices north of the Missouri River are
only expected to climb into the upper 90s and low-100s this
afternoon, so the Heat Advisory has been cancelled. South of the
showers and cloud cover, temperatures are still on track to
reach the mid-to-upper 90s with heat indices around and above
105F, so the Extreme Heat Warning remains in effect through 9 PM
this evening.

At the surface, a stationary front remain positioned across
northeastern KS and northern MO. This will be the focus point
for any potential convection this evening and overnight. In a
similar fashion to previous nights, most CAMs depict convection
blossoming across eastern KS and northern MO as the LLJ
interacts with the boundary. Expectation is for storms to
develop between 02Z and 05Z and last through much of the
overnight. Assuming storms are able to form(50-70% chance along
and north of the Missouri River), they will have 2500-3500 J/kg
of MUCAPE to work with. However, deep layer shear values are
only expected to be on the order of 15-20 kts, so organized
convection may be a bit more difficult to come by. This does not
mean severe weather is impossible as storms may still be able
to produce downbursts as they pulse up and down, so strong to
damaging winds are possible tonight. PWATs also remain on the
order of 2-2.5", which will allow storms to be very efficient
rainfall producers and may lead to locally heavy rainfall
beneath the strongest cores. This presents a flash flooding
threat, particularly if storms are able to train over the same
areas.

The front will begin to slide south overnight tonight, pushing
through the KC Metro early tomorrow morning. Most of the hi-res
guidance suggests that the front will exit the southern portion
of the CWA by mid-to-late morning tomorrow bringing much needed
relief from the heat and humidity. However, with the front
progressing through the area, there will likely be a gradient
in high temperatures, with low-90s possible across the southern
portion of the CWA to low-80s further north. A few elevated
showers and storms are possible (25-35% chance) across the area
Sunday afternoon, but no severe weather is anticipated.

Monday will see the coolest temperatures in quite some time with
highs topping out in the mid-80s. Precipitation chances are also
near zero on Monday for the first time in a while with the cold
front having fully exited the area. However, this brief benign
pattern will be short lived as another shortwave moves across
the Northern and Central Plains on Tuesday with an associated
surface front dropping south towards the area. Differences in
timing, placement, and intensity of the shortwave still exist
between model suites (both deterministic and ensemble). However,
a general consensus seems to be present regarding the
environment ahead of the system, with 2000-3000 J/kg of MUCAPE
and 25-35 kts of deep layer shear ahead of the surface front.
This parameter space points to a potential for organized
convection and the chance for severe weather. This thinking is
reflected in the SPC Day 4 outlook, which has the northern third
of the area in a Slight Risk (Level 2 of 5) for severe weather.

Model guidance diverges through the remainder of next week,
however, it seems as though most point towards a northwest flow
pattern setting up across the northern and central Plains, which
may lead to a more active stretch of weather.

&&

.AVIATION /00Z TAFS THROUGH 00Z MONDAY/...
Issued at 616 PM CDT Sat Aug 15 2026

Mostly VFR conditions are expected over the TAF period. A few
hours of variable winds are expected at the beginning of TAF
period before settling out of the north before dawn. Isolated
to scattered thunderstorms may develop north of the Missouri River
late this evening...PROB30 for -TSRA mentioned only at KSTJ due
to low confidence in the southern extent of overnight
convection. Closer to sunrise, a second round of thunderstorms
will be possible, again primarily in northeastern Kansas and
northern Missouri. A second PROB30 is included in the KSTJ
TAF...confidence in placement is not high enough for mention in
KMCI TAF. Chances for convection will be reevaluated for the
06Z issuance, at which point additional mentions of TSRA may be
required.

&&

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

&&

$$

DISCUSSION...Carothers
AVIATION...Macko