St. Joseph, Missouri 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

485
FXUS63 KEAX 151054
AFDEAX

Area Forecast Discussion
National Weather Service Kansas City/Pleasant Hill MO
552 AM CDT Wed Jul 15 2026

.KEY MESSAGES...

- Temperatures will continue to gradually climb over the next
  several days, with highs in the middle 90s forecast this
  weekend and upper 90s on Monday.

- Showers and thunderstorms return on Thursday afternoon, with a
  40-60% chance of precipitation for areas south of Highway 36.
  These storms could pose a threat for locally heavy rainfall
  gusty winds.

- Heat index values will reach the upper 90s to lower 100s
  Friday through this weekend, peaking around 100 to 105 degrees
  on Monday.

&&

.DISCUSSION...
Issued at 117 AM CDT Wed Jul 15 2026

Mostly clear skies tonight with temperatures mostly in the 70s
as of 11pm. Northeast Kansas and northwest Missouri remain
under the influence of a broad ridge and surface High across
much of the central CONUS leading to the clear skies, light
winds, and quiet weather. Some patchy fog, locally dense at
times, is expected near and north of a line from STJ to MBY.

Today we start to see a shift in the upper-level pattern as the
trough over the southeastern US pinches off from the upper-
level flow and migrates westward undercutting the ridge over the
Central US. This will start to advect more moisture back into
southern Missouri on through the day. Some of our southern
counties will see this boost in humidity with dew points
hovering near 70 through the afternoon, leading to heat indices
rising in to the upper 90s. While storm activity should stay to
our south, we will see increasing cloud cover especially over
these southern counties through the afternoon and evening as
well.

Thursday the moisture plume lifts north bringing the richer dew
points north into more of our area. This will also bring storm
chances (40-60%) to most of our area, generally areas south of
Highway 36 Thursday afternoon. Increased instability from this
additional moisture will allow diurnal heating to pop-off
scattered showers and storms through the afternoon despite
little-to-no upper-level forcing. Forecast soundings show very
weak deep- layer shear suggesting storms will struggle to
organize into anything longer-lived. The main hazards will be
from locally heavy rainfall and isolated damaging winds from
collapsing storms (wet microbursts). The bigger hazard will be
locally heavy rainfall due to weak steering flow and PWAT values
approaching/exceeding 2" (90th percentile climo for mid-July).
Localized flash flooding appears very possible with storms
Thursday afternoon and evening. Good news is that the diurnal
nature of these storms should lend to the activity shutting down
toward dark Thursday evening, with below-mentionable PoPs after
sunset.

Later in the week, the subtropical ridge builds up out of the
Southeast. This will ramp up the low-level jet over central
Texas on Friday and pushing it back into western Missouri Friday
night into early Saturday. Additional moisture advection from
the Gulf will only lead to an even greater increase in dew
points and moisture across our area. Nocturnal amplification of
the low-level jet could potentially lead to nocturnal storm
chances starting Friday night through the weekend. Ensemble
guidance continues to downplay this potential, keeping PoPs
around 15% or less, likely due to uncertainty in the placement
of any potential nocturnal MCS development, but deterministic
guidance continues to show potential for these storms through
the weekend.

Monday looks to see the peak of the heat and humidity as ridging
briefly expands eastward into the forecast area. This will
bring high temperatures in the upper 90s, possibly touching 100
in urbanized areas, and peak heat index values near or just
above Heat Advisory criteria of 105. By Tuesday, the ridge will
retreat to the southwest as troughing increases over the eastern
CONUS, leading to temperatures cooling to more typical late
July values with comfortable humidity values.

&&

.AVIATION /12Z TAFS THROUGH 12Z THURSDAY/...
Issued at 552 AM CDT Wed Jul 15 2026

Shallow fog will continue to impact STJ before diminishing around
13z. SCT diurnal CU is expected to develop again this morning, with
bases around 4-5kft. As high pressure translates from north of the
region this morning and afternoon to southeast of the area tonight,
steady E-NE winds around 4-7 kts will become SE tonight around 3-5
kts under passing high cirrus.


&&

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

&&

$$

DISCUSSION...McCoy/Snyder
AVIATION...Snyder