St. Joseph, Missouri 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

401
FXUS63 KEAX 031046
AFDEAX

Area Forecast Discussion
National Weather Service Kansas City/Pleasant Hill MO
546 AM CDT Mon Aug 3 2026

...Updated 12z Aviation...

.KEY MESSAGES...

- Warming Trend Starts

- Showers and Thunderstorms Start Tuesday Night, Become Widespread
  Wednesday

- Fluctuating Pattern End of Week

&&

.DISCUSSION...
Issued at 355 AM CDT Mon Aug 3 2026

Mid and upper-level ridge axis is still present from the Kansas High
Plains into Upper Midwest this morning, but upstream we are seeing
signs of deamplification as a stronger short-wave trough exits the
Pacific Northwest and heads for the Northern Plains and Canadian
Prairie Provinces. The stronger dAVA over the lower Missouri River
Valley the past few days has shifted toward the Ohio River Valley
and Tennessee Valley, and has forced the surface anticyclone center
eastward. Multiple short-wave perturbations over the Rockies has
provided enough dCVA and lift that has resulted in surface
cyclogenesis, with recent objective analysis having this centered
over eastern Wyoming this morning. The stronger mid-level support
will start to shift northeastward into the Northern Plains, which
will limit surface pressure falls for the forecast area, at least
for today. However the 594dam H5 high over the desert southwest is
also expected to deamplify over the next 24 hours. Expecting short-
wave activity to generate cyclonic vorticity into Colorado and the
Front Range through the evening, providing another area of surface
pressure falls which will extend southward from the cyclone
currently deepening over Wyoming. For the lower Missouri River
Valley, this sets lower tropospheric flow southwesterly, increasing
the strength of WAA this afternoon and will help boost temperatures
into the upper 80s across most of the areas, and a few locations may
potentially hit the 90F mark this afternoon. Moisture return today
will be fairly modest, and without any stronger mid-level lift over
the area, should help keep conditions dry for today. Western
Missouri and eastern Kansas may see an uptick in winds later in the
afternoon, but the stronger pressure gradient remains progged over
the Central Plains.

Tuesday, short-wave H5 trough moves a stronger lobe of vorticity
across the northern Plains, with mid-level height falls deamplifying
the ridge axis across the area. Additional mid-level vorticity
generates over the Rockies in Colorado, and this dCVA will help
promote surface pressure falls from the Front Range to the Central
Plains, while the cyclone over eastern Wyoming moves into the
northern Plains along with the primary short-wave trough axis. This
movement will also push a cold front into the Central Plains through
most of Tuesday afternoon. During this time in the afternoon, most
of the forcing remains well west and northwest of the forecast area.
However, flow from 850mb to the surface will become more southerly
through the afternoon, transporting a higher theta-e airmass into
the lower Missouri River Valley. Expecting temperatures to hit the
90s across much of the area, with steadily increasing dewpoints. The
afternoon still looks to remain dry for most of the area, but as the
cold front moves east-southeast along surface pressure falls
spreading across the Plains, convergence will increase eventually
bringing providing the lift needed for shower activity. Current
ensemble guidance pinpoints the highest probabilities for rain showers
in northern Missouri by late Tuesday Night. If there is enough CAPE,
a few rumbles of thunder may occur with this activity. The stronger
deep layer shear on Tuesday should remain over the central Plains,
which will limit the ability for activity to organize on Tuesday in
far northern Missouri.

Wednesday, another short-wave trough and enhanced mid-level vort max
is currently progged to dig further south, especially in the GFS
solution which will provide more lift along with the surface cyclone
and cold front moving toward the area. With continued south and
southeasterly flow near the surface, theta-e transport will
continue, and as the day progresses should see shower activity
spread across most of the forecast area. With the stronger mid-level
flow on Wednesday afternoon and evening, deep layer shear values
increase, with 0-6km bulk shear values potentially hitting near 40kt
especially close to thermal boundary. This will provide the support
needed to help storm activity organize, and may help produce
stronger to marginally severe storms. This morning`s SWODY3 outlook
places much of the area in a marginal risk (level 1 of 5). The
source of uncertainty is how much destabilization will be able to
occur Wednesday afternoon and early evening. With a lot of activity
expected over the Plains, we may end of with mid and upper-level
cloud cover, limiting insolation and the ability for the boundary
layer to destabilize. In addition, with deeper moisture transport,
model soundings are not showing any kind of EML development,
therefore, keeping lapse rates marginal as the forcing move through
the area on Wednesday. If stronger updrafts are able to develop, a
few severe wind gusts would be the primary threat, along hail around
quarter size. In addition to severe concerns, the moist column will
also provide support for deep warm cloud processes, and efficient
rainfall production. Current PWAT values are progged around 1.75 to
1.80 inches across much of the area, which could present hydro
issues especially in developed in areas. Rain shower activity likely
continues into Thursday, as more H5 disturbances roll through
providing broadscale lift across lower Missouri River Valley.
Activity begins to dwindle Thursday evening as the stronger mid-
level support then moves into the Great Lakes Region.

For the weekend, the weather pattern still appears to fairly
unsettled. Another H5 ridge and strong high attempts to develop over
the desert southwest which may force H5 height falls into the
Central CONUS, but remains in competition with stronger flow over
the Northern Plains and Canadian Prairie Provinces which may try to
send forcing further southward into the forecast area. Ensemble
guidance is still spread with respect to precipitation potential
heading into the weekend, resulting spreading 15 to 20 percent
probabilities across nearly the entire weekend. This also maintains
uncertainty with the temperatures forecast heading into the
weekend, with inner-quartile spread amongst NBM members and other
ensembles suites fairly large.

&&

.AVIATION /12Z TAFS THROUGH 12Z TUESDAY/...
Issued at 544 AM CDT Mon Aug 3 2026

Fog has developed in the Missouri River Valley, and in central
Missouri from Cooper County northward to the IA-MO state line.
Fog is also occurring at STJ in the river valley. The fog will
mix out after sunrise. VFR conditions will prevail for the
remainder of the afternoon.

&&

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

&&

$$

DISCUSSION...Krull
SHORT TERM...73
LONG TERM...73
AVIATION...Krull