St. Joseph, Missouri 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

484
FXUS63 KEAX 221111
AFDEAX

Area Forecast Discussion
National Weather Service Kansas City/Pleasant Hill MO
611 AM CDT Fri May 22 2026

.KEY MESSAGES...

* Rain chances to increase (40-60%) throughout the morning and early
  afternoon, mainly west of US-65.

* Saturday afternoon, showers and storms may develop along a cold
  front. The best chances (30-60%) for showers and storms look to
  reside across the southeastern portions of the CWA. Severe storms
  are not expected at this time.

* Warmer and drier for the remainder of the holiday weekend
  before rain chances return next week.

&&

.SHORT TERM /THROUGH SUNDAY NIGHT/...
Issued at 404 AM CDT Fri May 22 2026

Early overnight showers struggled to overcome low-level dry air,
leaving the vast majority of us dry so far early this morning. Just
a few hours ago, MRMS RALA imagery depicted collapsing elevated
showers in our southern Missouri counties with increasing shower
development across southeast Kansas and northeast Oklahoma in an
area of low-level frontogenic forcing. CAMs continue to show a
resident layer of dry air near the surface, though a moistening
trend is noted as we move through the morning hours. As such, CAMs
keep most of the CWA dry until sunrise, around which point showers
will begin to cross into the southern fringes of the area ahead of
the surface warm front. WAA driven showers are expected to increase
in areal coverage through the remainder of the morning and early
afternoon hours, primarily west of the US-65 corridor. With the
surface front anticipated to come to a near halt early Friday
afternoon, the northern and eastward extent of showers will likely
be limited. Instability is by and large weak across the region,
which will reduce storm potential to the occasional rumble of
thunder. Further north in eastern Nebraska, modest instability
develops by the late afternoon hours, which may be sufficiently
conducive for storm development. CAMs indicate that these storms
would move off to the east during the evening and overnight hours
but ultimately losing steam with time. Consequently, storm concerns
remain low, but far northeastern Kansas and northwestern Missouri
could see a brief shower or storm late this evening (20-40% chance).
In terms of rainfall accumulations, ensemble probabilities of >
0.25" range from 50-80% south of I-70 and 30-40% north of I-70. East
of US-65, the likelihood of receiving accumulations in excess of
0.25" is less than 10%. Generally speaking, higher rainfall
accumulations are greatest further south where isentropic ascent is
strongest and where PWATs approach/exceed 1.5".

Overnight Friday into Saturday morning, the weakening warm front is
expected to finally pass through the area. Not long thereafter comes
the cold front, however, which will keep low-end chances for showers
in the forecast for much of the day on Saturday. The greatest
probabilities for shower and storm develop reside in the
southeastern portions of the CWA where some weak to modest
instability may be able materialize during the afternoon. Organized
convection is unlikely with poor shear profiles, thus keeping strong
to severe storm concerns at bay. Moreover, storm potential will also
be dependent on the location of the cold front, as it could very
well be off to the southeast by the time adequate instability
arrives. Needless to say, Saturday continues to look like a very
conditional, sub-severe threat.

As high pressure begins to settle in on Sunday, the remainder of the
holiday weekend is expected to be calm. This brief reprieve will
allow for ample sunshine and warmer temperatures in the low/mid 80s
area wide.

&&

.LONG TERM /MONDAY THROUGH THURSDAY/...
Issued at 404 AM CDT Fri May 22 2026

An interesting synoptic scale pattern is in store for the extended
forecast period. Early next week, upper-level ridging is expected to
intensify over the Plains while a trough deepens along the West
Coast and another low-pressure system slows over New England. Medium
range guidance depicts the trough further west ejecting a series of
shortwaves into the Southern Rockies, inducing lee cyclogenesis
midweek. This lee cyclone, detached from upper-level flow
reminiscent of omega blocking, could hover over the Southern Plains
for several days mid/late week before degrading. It is expected that
this unusual setup will lead to a wet and unsettled weather pattern
for much of next week, though uncertainty is prolific this far
out.

&&

.AVIATION /12Z TAFS THROUGH 12Z SATURDAY/...
Issued at 558 AM CDT Fri May 22 2026

VFR conditions are expected to hold just a bit longer this
morning as showers attempt to creep north. Shower coverage is
anticipated to increase by mid-morning, dropping CIGs below IFR.
The likelihood of showers declines considerably as we progress
through the afternoon hours, though some lingering rain is
possible. CIGs should improve to MVFR early this afternoon with
VFR CIGs expected late afternoon. TSRA is possible across
northwestern Missouri late this evening, but with low confidence
in coverage and timing, a PROB30 was not included in the TAF
for KSTJ at this time. In the last few hours of the TAF period,
CIGs are expected to fall once again, leading to MVFR and IFR
conditions.


&&

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

&&

$$

SHORT TERM...Macko
LONG TERM...Macko
AVIATION...Macko