St. Joseph, Missouri 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

942
FXUS63 KEAX 201118
AFDEAX

Area Forecast Discussion
National Weather Service Kansas City/Pleasant Hill MO
618 AM CDT Sat Jun 20 2026

.KEY MESSAGES...

- Lingering light rains and isolated rumbles of thunder this morning

- Severe storms possible late tonight through Sunday. Heavy rain
  with flood potential is forecast. A Flood Watch is in effect.

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 206 AM CDT Sat Jun 20 2026

GOES Sounder data shows a bubble of higher precipitable waters over
eastern KS/OK this hour, which also lines up with a theta-e ridge
axis as well as convergence 925 mb winds over that area and into
west central MO. Some showers with occasional rumbles of thunder are
within this axis. Rain rates are not that impressive at this point,
so not worried about hydro concerns at this point.

Forcing for those showers should fade as we get to daybreak, with
less convergent low-level winds. Cannot rule out an isolated shower,
as we do have a weak wind shift depicted from NE KS ESE to central
MO. Of more interest will be expected development of an MCS over NE
later this morning. This system develops at the northern edge of a
Plains upper-level ridge and is expected to ride east southeast from
the location in the WNW flow aloft. It should move into our region
near daybreak Sunday. Ahead of that system, the airmass will be very
juicy for this time of year. 99th+ percentile for precipitable
waters, with readings near 2 inches possible. Given that airmass,
would not be surprised to see some showers/storms develop ahead of
the MCS. Thus will start off with isolated to widely scattered storm
potential 00Z Sunday but ramp up to categorical chances (80+
percent) after 06Z and through daybreak.

Again, the rainrates should be impressive. 00Z HREF shows a 10%
chance for 3"+ rainfall in a 3-hour period from 9-12Z, with a large
area of 50-70% chances for 1"+ rainfall in that same period. The
ECMWF Extreme Forecast Index continues to show an impressive
east/west band of anomalous QPF with a high shift of tails,
indicitive of rainfall outside of climo max in the database.

Above discussion focuses on what`s expected to be the main threat
with these storms...the heavy rainfall. That said though, with a
warm frontal boundary in the area, we could see a corridor of
tornado potential, with better low-level shear, as well as some
stronger wind gusts as the cold pool from the MCS pushes through. A
lot of factors to consider with this system.

&&

.LONG TERM /SUNDAY THROUGH FRIDAY/...
Issued at 206 AM CDT Sat Jun 20 2026

After that MCS moves through the region early Sunday, we anticipate
a trailing outflow boundary for new storms to develop along. Given
the continued moist airmass in and the potential some training
storms could develop across our southern forecast area, we decided
to expand the Flood Watch to include all of our counties.

One other thing to note, we could see some gusty wind potential a
couple of ways Sunday. Sometimes in the wake of an MCS, you get a
wake low to form. Interesting that HREF wind gusts show easterly
winds behind the MCS, with speeds 25-40 kts. Would not be surprised
if they are stronger than that in isolated pockets, but something to
watch for. South of that track, we`ll also have some 25-35 kt low-
level jet winds across central MO. Cloud cover should limit these
winds from mixing down, but if we see more breaks in the clouds than
anticipated, then some gusty conditions are possible in central MO
as well.

Between the Saturday night and Sunday rains, we should see a swath
of 2-3" in northern MO (with locally higher amounts)...then another
swath of 2-3" where that training sets up and a gap of 1-2" totals
in between.

After the rains Sunday, we should see a relatively dry period Monday
through Wednesday. A few models spit out isolated diurnal showers
Tue, but NBM keeps pops silent below 15 percent. Slightly more
members show showers Wednesday afternoon, so NBM introduces isolated
chances for the KC Metro area. Coverage looks a bit better to close
out the work week, as general troughiness resides over the region.

After Saturday being our warmest day and night, with readings near
normal, the rest of the 7-day forecast looks to be just below
normal.

&&

.AVIATION /12Z TAFS THROUGH 12Z SUNDAY/...
Issued at 617 AM CDT Sat Jun 20 2026

High pressure over the region this morning will bring light and
variable winds this morning. An approaching storm system will
switch those winds to easterly by early afternoon. We`ll see
some widely scattered storms this evening before a more solid
line of storms moves in from the west. This line likely will
have stronger west winds initially than what is in this set of
TAF`s, but then as storms continue to daybreak Sunday easterly
winds should dominate again. Will keep this set of TAF`s simpler
for now, given those storms are in the outlook period.

&&

.EAX WATCHES/WARNINGS/ADVISORIES...
MO...Flood Watch from this evening through Sunday evening for
     MOZ001>008-011>017-020>025-028>033-037>040-043>046-053-
     054.
KS...Flood Watch from this evening through Sunday evening for
     KSZ025-057-060-102>105.

&&

$$

SHORT TERM...Sharp
LONG TERM...Sharp
AVIATION...Sharp