St. Joseph, Missouri 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

977
FXUS63 KEAX 261136
AFDEAX

Area Forecast Discussion
National Weather Service Kansas City/Pleasant Hill MO
636 AM CDT Sun Apr 26 2026

...Updated 12z Aviation...

.KEY MESSAGES...

- Conditional Threat for Severe Storms Late Afternoon Sunday

- Strong to Severe Storm Clusters Expected Sunday Evening Through
  Overnight

- Additional Severe Threat Continues Into Monday; Uncertain Evolution

- Flooding Issues Possible With Heavy Rainfall Sunday Night through
  Monday Night

&&

.DISCUSSION...
Issued at 431 AM CDT Sun Apr 26 2026

Subtle H5 ridge axis across the area will shift eastward through the
morning hours and will give way to mid-level height falls by the
afternoon as a primary trough axis begins to lift out of the desert
southwest today. Stronger dCVA will begin to occur across the
Central and Southern High Plains this afternoon which will provide
the lift needed to deepen the surface cyclone currently positioned
over the Texas Panhandle. Cold front that triggered convection over
Central Kansas has stalled overnight positioned from northwest of
Wichita to just west of Des Moines. This is progged to remain
stalled while the surface cyclone deepens today, with southerly
surface flow increasing through the afternoon. WAA will steadily
allow temperatures to climb into the mid and upper 70s this
afternoon, and increasing moisture transport will send dewpoints
into the mid 60s. However stronger mixing will be possible this
afternoon that could take dewpoints back down into the lower 60s
after the 20z time frame. The first wave for vort maxima to traverse
from eastern Kansas into the lower Missouri River Valley will be
after 16z late this morning into the early afternoon. The HRRR and
other CAMs have developed a few cells along with this forcing,
though struggle to sustain them likely due to the fact that they
move away from the cold front. Deep layer shear will be pushing 40-
50kts by the afternoon as mid-level flow steadily increases, which
may foster better organization of storms. Increasing theta-e
deficits from the surface to the top of the convective boundary
layer may promote potential for stronger showers or storms in the
late afternoon to produce damaging wind gusts if the updrafts become
tall enough. Elongated hodographs perhaps could foster hail embryo
growth if a persistent updraft is able to develop, but may be
limited if forcing is not persistent enough. But if a storm is able
to overcome weaker lift, could see hail diameter above 2 inches in
the most robust storms. The severe threat for convection between 20z-
00z late this afternoon is uncertain though, with fairly skinny CAPE
profiles as this first wave moves through.

Stronger deep convective initiation is expected across Central Kansas
late this afternoon through early evening, closer the cold front.
MUCAPE values per 00z HREF mean will push above 2000 J/kg from
Interstate 135 corridor eastward to western Missouri. Deepening
surface cyclone will back surface winds over central Kansas curving
the low-level hodograph, while mid and upper-level jet streak moves
ahead extending the upper portions of the hodograph. This
environment should be enough to promote supercell development east
of Interstate 135. However for our counties in extreme eastern
Kansas, a supercell storm mode may be hard to achieve, especially
with the primary deep convection initiation occurring much further
west. While the background environment could support a supercell
mode into eastern Kansas and far western Missouri, the more likely
scenario will be for discrete convection over Central Kansas to
congeal and grow upscale through the evening as the low-level jet
intensifies, potentially pushing above 50 kts. The 00z and 06z HRRR
have shown upscale growth after 00z this evening, with a few bowing
segments suggestive of damaging wind. The low-level hodographs in
model soundings show a drastic increase in cyclonic curvature as the
low-level jet kicks in, with SRH values in the 0-1km layer possibly
pushing above 350 m^2/s^2. Hodographs are elongated from 3km and
above which will help updrafts persist and provide potential for
cold pools to balance. It may actually be possible for some of these
segments to take on a hybrid storm mode that could feature some
supercell characteristics to them that would actually foster larger
hail growth, still above 2 inches in diameter, and with the wind
threat, could even foster a setup for wind driven hail. Main
question with late evening activity is if there would be enough CAPE
in the hail growth zone, but, if one of these segments develops a
stronger mesocyclone, could overcome any thermodynamic issues to
develop large hail. As for the tornado threat, the low-level shear
is expected to be there, as well as overall SRH values. However, the
storm mode and location of initial deep convection will play large a
role. Cold pool propagation may result in storm motions that would
make vorticity ingest more crosswise than streamwise, which would
limit tornado potential, but still provide enough for large hail. 0-
3 km bulk shear magnitude should steadily increase above 30 kts
heading into the overnight hours, and if it aligns perpendicular
with any segment, may lend itself to favorable mesovortex
generation. We will also need to monitor the 0-3km MLCAPE profile
though, as this could be a limiting factor in any QLCS spin up
activity. Another conditional tornado scenario with a bowing segment
would be the development of a strong rear inflow jet that develops a
bookend vortex and deeper mesocyclone. With the background kinematic
environment, this is may not be out of the question, just depends on
how long things can stay in balance before any outflow pushes out.
The primary bowing segments move into eastern Missouri between 10-
12z Monday morning. Additional development of elevated convection
may be possible on the backside of the system though, with another
mid-level vort maxima pushing through, and perhaps the cold front
still around with the surface low pushing into eastern Kansas. The
HRRR at least has developed new convection into the middle of Monday
morning, though thermodynamically may not have much to work with.

This then leads to a messy setup for Monday afternoon and evening
mainly across Central Missouri. With the surface cyclone still
moving through, lift will still be present through Monday. The big
question is how will overnight activity linger into the afternoon.
Will there be any remnant outflow boundaries that promote strong
differential heating? Might an MCV develop somewhere in the region
that ignites another round of convection? Another potential scenario
is that overnight activity lasts through sunrise, and is able to tap
into new instability and re-intensify, which could allow storms to
become severe again. The background kinematic environment will still
remain quite robust re-invigorating activity, even if convection
becomes elevated. Overall, the better parameter space for Monday
afternoon is along and east of the Mississippi River Valley, where
the center of this morning`s issuance of SWODY2 has the level 3
enhanced risk. While it is hard to pinpoint specific hazards, the
main message is that severe weather may not be done Monday
afternoon, at least until the cold front clears the area.

Hydrology:

PWATs across the area will range from 1.30 to 1.50 inches while the
primary forcing moves through. Warm rain processes and potential for
tall-skinny CAPE profiles may lend itself to efficient rain rates
Sunday Night through Monday Night. There is still uncertainty with
the track of heaviest axis of QPF, but HREF LPMMs have been hinting
at pockets of 3-4 inches of rainfall along the Missouri River,
while mean QPF values sit around 2 inches. Current Flash Flood
Guidance for 3 hours of QPF is generally in the ballpark of 2 to 2.5
inches of rainfall, which could be achieved. Further, the event
from Thursday 4/23/2026 may still have the soil heavily saturated in
a few spots, along with a few rivers/streams that are still running
at elevated levels. While storm motions may be fast and progressive,
persistent forcing overnight into Monday morning may lead to new
development and training between Interstate 70 and Hwy. 36,
presenting potential for Flash Flooding. A Flash Flood Watch has
been issued for this general area. An expansion may become
necessary if we see any shift in the heaviest QPF axis, and perhaps
the 12z HREF will be able to provide more insight into the hydro
issues that will be possible.

&&

.AVIATION /12Z TAFS THROUGH 12Z MONDAY/...
Issued at 633 AM CDT Sun Apr 26 2026

Isolated to scattered showers/storms possible this afternoon,
and fluctuating ceilings between low-end VFR and MVFR expected
as low pressure strengthens. Strong storms are expected to
develop in central Kansas later this afternoon, and eventually
congeal into a cluster of storms. These are likely to arrive
around the KS-MO state line between 00-03z. Additional
development is possible behind this. Ceilings will be low-end
MVFR, with down pours potentially resulting in periods of IFR
visibility.

&&

.EAX WATCHES/WARNINGS/ADVISORIES...
MO...Flood Watch from this evening through Monday evening for
     MOZ011>014-020>025-028>033-037>040.
KS...Flood Watch from this evening through Monday evening for
     KSZ025-102>105.

&&

$$

DISCUSSION...Krull
AVIATION...Krull