St. Joseph, Missouri 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

945
FXUS63 KEAX 151118
AFDEAX

Area Forecast Discussion
National Weather Service Kansas City/Pleasant Hill MO
618 AM CDT Sat Aug 15 2026

.KEY MESSAGES...

- A Flood Watch is in effect through Saturday morning for
  counties in north-central and northeastern Missouri. Training
  storm clusters will be capable of producing heavy downpours
  that may lead to flash flooding.

- Hazardous heat continues today. An Extreme Heat Warning is in
  effect until 9 PM for areas generally along and south of the
  Missouri River. A Heat Advisory is in effect until 9 PM for
  areas in the vicinity of the US-36 corridor.

- Additional thunderstorm chances Saturday night into Sunday,
  generally between the IA/MO state line and the Missouri River.

- Some relief from the heat is expected heading into next week.

&&

.DISCUSSION...
Issued at 116 AM CDT Sat Aug 15 2026

Convection is ongoing north of the Missouri River following the
intensification of a now 30-40 kt low-level jet against the
stationary boundary draped across portions of northern MO and
eastern KS. Recent mesoanalysis depicts 2500-3000 J/kg MLCAPE across
the CWA with a gradient of PWATs between 2.0 and 2.5 from the I-70
corridor up through the IA/MO border, respectively. Storms clusters
are already showing the tendency to congeal and train in an
environment lacking adequate deep-layer shear. Additional
development is expected as the low-level jet continues to provide
lift in the frontal zone overnight, increasing potential for
training roughly along and north of US-36. A severe threat does
still exist, albeit marginal, with isolated strong wind gusts
possible, but flash flooding remains the main concern as we progress
through the overnight with continued training and weak upper-level
flow. Backbuilding will cease as the low-level jet decays later this
morning. Weakening showers and storms may linger briefly after
sunrise before coming to an end mid/late morning.

The stationary boundary will hold over northern MO/southern IA for
much of today as the ridge begins to slide east. Hot and humid
conditions are once again expected with heat products in effect
until late this evening for areas generally in the vicinity of US-36
and south. Any lingering cloud cover could limit temperatures today,
especially across northern MO. Max heat indices could sit around
105F south of the river with heat indices around 100F further north,
but this forecast will be sensitive to the persistence of cloud
cover.

The stationary front is expected to sag south late Saturday night
into early Sunday morning, bringing storm chances to the region once
again. Northern MO once again appears to have the greatest
likelihood of storms (50-70% chance), though there is a 20-30%
chance into far east-central KS and central MO. There are questions
regarding the cold front behind the stationary front that is set to
move through the area sometime between early Sunday morning and late
Sunday night. Some guidance projects the passage to occur by
sunrise, leading to cooler conditions (high temperatures in the
low/mid 80s) areawide, while others suggest a slower progression
that leads to the temperature gradient dividing the CWA (low 80s in
the north versus low 90s in the south). Needless to say, there is
considerable timing uncertainty having significant implications for
Sunday`s temperature forecast.

&&

.AVIATION /12Z TAFS THROUGH 12Z SUNDAY/...
Issued at 612 AM CDT Sat Aug 15 2026

VFR conditions are expected through the day with southerly winds
5-10 kts. Chances for showers and storms increase after 00Z and
continue into the overnight. Brie reductions in flight
conditions are possible with this activity. Additionally, there
is a low probability (<20%) for MVFR ceilings and visibility
late in the forecast. Given it`s in the last 6 hours of the
forecast and low chance of occurring, have left mention out for
now.

&&

.EAX WATCHES/WARNINGS/ADVISORIES...
MO...Extreme Heat Warning until 9 PM CDT this evening for
     MOZ028>033-037>040-043>046-053-054.
     Flood Watch until 10 AM CDT this morning for MOZ003>008-
     013>017-022>025.
KS...Extreme Heat Warning until 9 PM CDT this evening for KSZ025-
     057-060-103>105.

&&

$$

DISCUSSION...Macko
AVIATION...CDB