St. Joseph, Missouri 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

444
FXUS63 KEAX 172340
AFDEAX

Area Forecast Discussion
National Weather Service Kansas City/Pleasant Hill MO
640 PM CDT Sun May 17 2026

.KEY MESSAGES...

- Active weather pattern continues this week.

- Strong to severe storms will be possible early Monday morning as
complex of storms builds south weakening with time.  Main threats
will be damaging straight line winds and a short lived tornadoes-
especially across northwest Missouri.

- Additional severe storms are expected Monday night into Tuesday
morning as a cold front builds south across the region.  Large hail,
damaging winds, tornadoes and flooding are all possible with this
round of thunderstorms.

&&

.DISCUSSION...
Issued at 258 PM CDT Sun May 17 2026

A very active stretch of weather is expected to continue across the
region with a slow moving cold front expected to be the focus for
rounds of thunderstorm development.  Early this afternoon, a pair of
supercells developed near the front in north central Nebraska
lifting northeast into southeast South Dakota along the front.  Warn
on forecast and CAMs are largely in decent agreement that storms
will try to build south with time, though there is a bit of a cap
that developing updrafts will have to work around.  Convergence on
along the front is expected to increase this evening as 30-50 knot
low level jet develops in the open warm sector from central Texas
into central and eastern Kansas. Subtle short wave across northern
Kansas this afternoon is expected to lift northeast and aid in
thunderstorm development along the front this evening. Storms will
be developing in a fairly volatile environment with 2000-2500 J/kg
of ML CAPE and 30-40 knots of bulk shear.  As storms evolve into a
line/ complex, they are expected to leave the cold front behind
extending from central-eastern KS into central Iowa. 0-3 km helicity
is currently 200-300 m2/s2, but as the low level jet increases, 0-1
km helicity is expected to increase over 300 m2/s2. Therefore, as
the developing MCS builds south into northwest Missouri expect a
tornado threat along with damaging wind threat. As MCS builds south
of highway 36, expected storms to become outflow dominant with
strait line winds becoming the primary threat and weakening in time
as the complex works farther south.

Upper level jet streak is expected to round the base of the upper
level trough tonight and eject into the plains tomorrow aiding to
strong wind shear.  Remaining front may reorient slightly as main
shortwave in upper level trough rounds the base of the trough and
surface low develops in western KS progressing northeast along the
front throughout the day.  Volatile environment is expected to
develop on Monday ahead of the front with 3500-4000 J/kg of SB CAPE
and 0-6 km effective shear of 30-35 knots. Storms are expected to
develop along the front in eastern KS quickly growing upscale into a
cyclone/developing MCS that is expected to build southeast through
the evening hours.  All hazards are expected with this complex of
storms including damaging winds, large hail, flooding and tornadoes.

Have expanded the flood watch across north central Missouri south,
and may need to continue the trend tonight to include the KC metro,
but didn`t get too aggressive since the storms tonight are expected
to be fairly progressive with expected rainfall expected to be an
inch or less in most locations.  With that said though, flash flood
guidance is very low in locations that received copious amounts of
rain last night.  Precipitable water ahead of the front is expected
to climb to 1.75-2.00" and with deep warm cloud processes.

Cooler and drier conditions are expected in the wake of the frontal
passage Tuesday into Wednesday; however, additional precipitation is
possible late week as a trough develops across the Northern
Plains.

&&

.AVIATION /00Z TAFS THROUGH 00Z TUESDAY/...
Issued at 633 PM CDT Sun May 17 2026

Deteriorating flight conditions through the overnight. Breezy
low VFR conditions continue for the next few hours before
degrading through the night as a thunderstorm complex moves
through.

Gusty southerly winds continue ahead of the line of
thunderstorms that is expected to enter the region around 05-06Z
in vicinity of KSTJ. The line is expected to progress SE
through the remaining terminals over the following 6 hours. High
winds and heavy rainfall are the primary hazards with this line
of storms. Gusty winds around 25-30 knots continue after storms
more through persisting through the remainder of the period.
CIGs lower to low MVFR ahead of storms with borderline MVFR/IFR
conditions continuing through the end of the period.

&&

.EAX WATCHES/WARNINGS/ADVISORIES...
MO...Flood Watch from 1 AM CDT Monday through Tuesday morning for
     MOZ020>022.
     Flood Watch through Tuesday morning for MOZ001>007-011>016-023-
     024.
KS...Flood Watch from 1 AM CDT Monday through Tuesday morning for
     KSZ025-102.

&&

$$

DISCUSSION...BT
AVIATION...Pesel