St. Joseph, Missouri 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

241
FXUS63 KEAX 212301
AFDEAX

Area Forecast Discussion
National Weather Service Kansas City/Pleasant Hill MO
601 PM CDT Tue Apr 21 2026

.KEY MESSAGES...

* Above normal temperatures and breezy south southwesterly winds are
  expected today through Thursday.

  - Windiest day Thursday with gusts in the mid-upper 30s mph likely

* Showers and thunderstorms return to the forecast Thursday, as
  early as the afternoon but with greater chances into the evening
  and overnight hours.

  - Strong to severe storms and locally moderate to heavy
    rainfall will be possible. Damaging winds and hail appear to
    be the primary thunderstorm threats.

* Unsettled/active weather across the wider area likely
  continues into the weekend and early work week, especially
  Sunday PM into Monday AM.

&&

.DISCUSSION...
Issued at 256 PM CDT Tue Apr 21 2026

Looking at the big picture, overall quiet conditions tended to
prevail across the immediate area with mid-upper level NW flow
continuing to prevail. A shortwave riding through this flow is noted
on GOES WV imagery, with most pronounced lift/indications crossing
Lake Michigan. This too is reflected on radar with storms initially
going up in that area and in the vicinity of surface boundary and
ribbon of moisture. Hi-res guidance has tended to ease off "lighting
up" the convergence area/moisture ribbon back to the SW, leaving the
area dry. That said, should bit deeper lift be achieved back
toward/along the eastern Iowa/Missouri border, a thunderstorm or two
may yet be possible into the early evening. Shear profiles are not
terribly supportive of any organization, so expectation would be
pulsey storms mostly capable of non-severe hail and wind. But,
again, probabilities here are quite low given recent hi-res trends.

Wednesday sees mid-upper level ridging build across central CONUS in
response to large mid-upper trough moving onshore and into the
Intermountain West. This keeps overall conditions quiet, but likely
at least a cloudier start to the day with increasing low-level
moisture return. Said cloud cover likely keeps temperatures down a
couple degrees versus today as well. Otherwise, areas well to the
north (Iowa/Nebraska) will be notably warmer with clear skies and
the 850mb thermal ridge nosing into those areas.

Thursday will see active weather and storm chances return to the
area as the previously mentioned western trough begins to move out
into the High Plains. Areas of Lee Cyclogenesis coupled with the SE
CONUS surface high will yield another breezy/windy day with SW wind
gusts likely into the mid-upper 30s mph for much of the area. Aside
from the low level WAA and moisture advection, the area too will see
deeper moisture begin to return. While not extreme, forecast PWats
of >1.25 inches push toward 90-95 percent of season climatology via
GFS/Euro ensembles. More on that in a second. Warm sector
environment tends to be a bit messy with expected cloud cover and
some expectation of elevated shower/non-severe storm potential
Thursday morning along the leading edge of strong WAA push and
deeper moisture return. How much does the environment then
destabilize ahead of the front later in the day/evening? Great
question. Prevailing sentiment is that with relatively tight T/Td
spreads in place, >1000-1500 J/kg MUCAPE may be able to be achieved
within moderate lapse in the profile. Further west closer to the
front (central/eastern Kansas), better chances for clearing yield a
ribbon of MUCAPE values >2000-2500 J/kg nosing northward. Overall
wind profiles yield mean winds mostly parallel to the surface front
and limited opportunity for discrete organization to move off of and
remain discrete. Conceptually, this tends to yield convection
quickly lining out along/just ahead of the front and being ushered
eastward. Concerns would initially be for hail and wind, then
transitioning to wind and heavy rain. Deep wind profiles/orientation
tend not to appear supportive of prolonged strong/severe MCS
capability, but possible local scale evolutions yield a longer
sustained strong/severe bowing segment. The depicted front is
progressive through the area, which should limit water issues, but
areas that see a couple/few storms stream over may see some
localized water issues with efficient rainfall (longer/skinnier CAPE
profiles) and the increasing PWats. Timing wise, guidance points
towards an evening into early overnight event for much of the area,
with initial storms going up over central/eastern Kansas
around/after 5-6pm and then translating E to SE.

Mid-upper level pattern takes on more of an Omega Block look as the
western CONUS mid-upper trough develops into a cutoff low near/along
the US-Canadian border and amplifies a narrow area of ridging over
the Great Lakes. This looks to keep the area on the cool side of the
pattern and relatively active, including multiple shortwaves and a
stalled front lifting back northward. Temperatures Friday, through
the weekend, and into next week ease back a handful degrees, around
or just above seasonal norms this time of the year. This also tends
to place Sunday into Monday as the highest confidence shower/storm
windows as a stronger shortwave trough moves through the southern
stream and induces pronounced Cyclogenesis. Model discrepancy in
N/S placement and potentially gunky environment ahead of the
surface low limits confidence in details for strong/severe
potential, but would be the next opportunity.

&&

.AVIATION /00Z TAFS THROUGH 00Z THURSDAY/...
Issued at 558 PM CDT Tue Apr 21 2026

Gusty south winds are expected through much of the period.
Exception to this may be when cloud cover across southeastern KS
into Oklahoma builds north into the region. Models suggest
ceilings will initially be VFR, but gradually build towards MVFR
overnight and continue into Wednesday morning. There is some
question how quickly these ceilings scatter out Wednesday
afternoon. For now, went with an optomistic 18Z.

&&

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

&&

$$

DISCUSSION...Curtis
AVIATION...BT