St. Joseph, Missouri 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

464
FXUS63 KEAX 192046
AFDEAX

Area Forecast Discussion
National Weather Service Kansas City/Pleasant Hill MO
346 PM CDT Sat Sep 19 2026

.KEY MESSAGES...

- Showers and thunderstorms likely (30-50%) areawide tonight and
tomorrow morning, with highest likelihood (60-75%) across eastern
KS/western MO. Primary hazards include heavy rainfall, hail, and
severe winds.

- Lingering probabilities (30-50%) for showers/storms tomorrow
afternoon and evening; higher potential exists further south and
east.

- Temperatures cool into next week.

&&

.DISCUSSION...
Issued at 344 PM CDT Sat Sep 19 2026

Areawide, temperatures have climbed into the low/mid 90s amidst
daytime heating and ample warm/moist transport from the southwest on
the back edge of a low-level ridge. Presently, a weak band of
showers/storms have begun to pop up along the slowly advancing cold
front situated right at the intersection of the IA/NE/MO state
lines. This cold front, along with a slowly encroaching
shortwave situated over central Kansas, will be the main story
for the short term forecast period.

As the cold front continues slowly pushing southeastward, it will
encounter an airmass with ample instability (2000-2500 J/kg MUCAPE)
and increasing shear (30-35 kts). With ascent along the cold front
exacerbated by the oncoming shortwave and its associated vorticity
advection/height falls, the potential for thunderstorm development
across eastern Kansas and western Missouri this evening continues to
look likely (60-75%). Looking to specific hazards with these
thunderstorms, the signal continues to trend towards severe
wind/hail, with steepening mid-level lapse rates out ahead of the
cold front and elevated DCAPE ~1000 J/kg. However, the greater
opportunity for larger hail resides further towards the southwest of
the forecast area, as storms initiate along the boundary amidst
higher CAPE and effective bulk shear. The larger focus for severe
threats going into the evening will be towards severe wind as storms
congeal and become more elevated/cold pool dominant as they push
east/northeast. There continues to be an additional risk for heavy
rainfall creating localized hydro concerns, but overnight activity
looks to remain progressive enough that even 6 hourly accumulations
look to remain below flash flood guidance across the area. However,
the environment still remains favorable for efficient rainfall in
the strongest storms (PWATs ~2"), and any training thunderstorms
could increase hydro concerns with continued rainfall accumulations,
especially if the cold front slows/stalls over time.

Speaking of the front potentially slowing/stalling... Recent model
guidance has trended towards slowing down the forward progression of
the cold front overnight into tomorrow morning, with storms
lingering through at least the late morning. Severe potential
decreases through the overnight period, but stronger storms could
still pose a wind/hail risk with elevated CAPE and continued
steepening lapse rates with the front. Potential activity tomorrow
afternoon/evening will depend on the location of the cold frontal
boundary in relation to further shortwave perturbations in the
atmospheric flow, as there looks to be some lingering instability in
the atmosphere that could be invigorated with synoptic ascent and
organized by sufficient shear. Recent CAM guidance has not been
incredibly helpful in agreeing on one particular solution over the
other, with scenarios ranging from quiet weather to a complex of
thunderstorms pushing through the forecast area by the late
afternoon/early evening depending on the placement of the synoptic-
scale features. With continued uncertainty in the exact position of
these mechanisms, have elected to once again lower and broaden PoPs
across the area tomorrow afternoon/evening, with the potential
existing for scattered showers/storms but uncertainty remaining
higher in exact timing/location.

Any remnant activity from Sunday will gradually phase out by Monday
evening as the cold front continues to push towards the southeast
out of the forecast area. At the synoptic scale, predominantly
northerly flow on the backside of a retreating upper trough will
introduce much cooler and drier conditions through the early half of
next week, with daytime highs and overnight lows cooling down to the
60s and 50s, respectively. By the later half of next week, ridging
looks to build back across the southern half of the CONUS, with
guidance progressively indicating warmer and wetter conditions with
the intrusion of shortwave perturbations in the upper-level flow off
the Rockies.

&&

.AVIATION /18Z TAFS THROUGH 18Z SUNDAY/...
Issued at 1244 PM CDT Sat Sep 19 2026

Presently VFR at all terminals. Currently seeing gusts of 20-25
kts starting to spread northward from enhanced daytime mixing,
so have included prevailing lines for those gusts to persist
through sundown (2-3z) at downtown terminals. Primary concern
is TSRA impacting terminals this evening, with FROPA shifting
winds out of the north and lowering cloud ceilings. Have a
general timing of 1-10z for -SHRA, with narrower timing of 1-5z
for TSRA impacts across western terminals. Activity is
projected to spread eastward through the overnight, with lower
certainty in continued weather generally north of KIXD tomorrow.
However, with FROPA fully realized by 10z, guidance has
indicated degrading ceilings from north to south. Have included
mentions of these lowering cloud ceilings to low MVFR at the end
of the forecast period, with high IFR possible.

&&

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

&&

$$

DISCUSSION...SPG
AVIATION...SPG