St. Joseph, Missouri 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

889
FXUS63 KEAX 142330
AFDEAX

Area Forecast Discussion
National Weather Service Kansas City/Pleasant Hill MO
630 PM CDT Fri Aug 14 2026

.KEY MESSAGES...

- Dangerous heat continues for most areas today and Saturday.
  An Extreme Heat Warning remains in effect for areas generally
  along and south of the Missouri River today. A Heat Advisory
  remains in effect for area north of the warning through the
  Highway 36 corridor.

- Thunderstorm chances continue with the most likely corridor from
  the Missouri River northward to the IA/MO state line.

- Some relief to the heat is likely next week, in the wake of a
  cold front.

&&

.DISCUSSION...
Issued at 230 PM CDT Fri Aug 14 2026

The synoptic pattern of late remains largely unchanged with
500-hPa ridging across the central CONUS. An MCV located over
eastern NE and western IA can be seen in satellite imagery and
is reflected by a weak shortwave moving through the flow. At the
surface, a stationary front remains parked across northern MO
with hot and humid conditions to the south of the boundary.
Cloud cover and scattered showers have been present through much
of the day thus far across northern MO and are tied to forcing
from the MCV and shortwave. This has helped to limit
temperatures along and north of US-36. Cloud cover has also been
present over central MO, however, a clearing trend has been
noted over the past several hours and expectation is for
temperatures to climb into the mid-to-upper 90s this afternoon
with dew points in the mid-70s. This will result in heat indices
once again making a run towards 110F and thus the Extreme Heat
Warning and Heat Advisory remain in effect through 9 PM
Saturday. With the showers across northern MO, it is possible
that areas in the Heat Advisory may remain below criteria today,
however, hot and humid conditions are expected again tomorrow,
so opted to leave the advisory in effect.

The MCV is expected to track eastward across IA this afternoon
and into the overnight hours, inciting convection in central and
eastern IA this evening. Current expectation is for this
convection to follow the CAPE gradient east-southeastward
through IA, which would largely keep storms to the north of the
area. However, many of the CAMs depict storms initiating off of
the stationary front in northeastern MO as the forcing
associated with the shortwave moves through. As such, have
opted to include a 20-40% chance of storms across northeastern
MO through the evening and overnight hours to account for this.

If storms are able to form, they would have 2000-3000 J/kg of
MUCAPE (1000-2000 J/kg of MLCAPE south of the stationary front)
and 25-35 kts of deep layer shear to work with, so it is not
out of the question to see organized convection overnight
tonight across northeastern MO. The primary threats would be
strong winds and quarter-size hail, however, with a surface
boundary in play, a tornado or two cannot be ruled out where
surface vorticity is maximized. Another note of concern stems
from the 2-2.5" PWATs across northern MO. This, along with deep
warm cloud layers, will allow storms to be very efficient
rainfall producers and may lead to flash flooding, particularly
if storms train along the stationary front. All of this to say,
that any convection that is able to form across northern MO this
evening and overnight will be worth keeping an eye on.

Saturday will see more of the same with the stationary front
remaining stalled across northern MO, allowing extreme heat to
build across central MO (heat indices of 105-110F). The front
will once again be a focal point for convection Saturday
afternoon and evening as another weak shortwave moves overhead.
With 2500-3500 J/kg of MLCAPE available, the primary limiting
factor for organized convection will be deep layer shear values
of 15-20 kts. As such the primary concerns on Saturday are
locally heavy rainfall (PWATs remain in the 2-2.5" range) and
gusty winds. Timing remains a bit uncertain at this point, but
the most optimal window looks to be tied to peak heating from
mid-afternoon through the evening hours.

The stationary boundary will finally begin moving southward as a
cold front on Sunday. While Sunday will still be hot and humid
ahead of the front, this will bring much needed relief from the
oppressive conditions to the area by Monday. No heat products
have been issued for Sunday at this time as the timing of the
frontal passage will dictate how high the heat indices will get,
however, a Heat Advisory or Extreme Heat Warning may be needed
along and south of the Missouri River with future forecast
cycles.

Uncertainty in the forecast climbs as model guidance diverges
into next week. The ECMWF and its ensemble want to build another
ridge over the central CONUS while the GFS and GEFS depict a
string of shortwaves through next week, which would result in
cooler and wetter conditions. Suffice it to say, the forecast
will need to be monitored over the coming days to see if the
relief from the heat and humidity will last or if another heat
wave may be on the way.

&&

.AVIATION /00Z TAFS THROUGH 00Z SUNDAY/...
Issued at 623 PM CDT Fri Aug 14 2026

VFR conditions currently present at all terminals. Through the
afternoon, light showers have begun to crop up around the
forecast area. However, with drier low-levels and
elevated/isolated nature of showers, not confident in
prevailing weather at terminals presently. Anticipating TSRA to
develop across northern Missouri overnight, with some guidance
indicating impacts to KSTJ. Have elected to place a PROB30 for
-TSRA at KSTJ with this in mind around 3-6z. Winds presently
 out of the east/southeast at terminals, which are expected to
 shift southwesterly through the forecast period. Ceilings
 remain elevated, and are expected to rise through the forecast
 period.


&&

.EAX WATCHES/WARNINGS/ADVISORIES...
MO...Extreme Heat Warning until 9 PM CDT Saturday for MOZ028>033-
     037>040-043>046-053-054.
     Heat Advisory until 9 PM CDT Saturday for MOZ011>015-020>025.
KS...Extreme Heat Warning until 9 PM CDT Saturday for KSZ025-057-
     060-103>105.
     Heat Advisory until 9 PM CDT Saturday for KSZ102.

&&

$$

DISCUSSION...Carothers
AVIATION...SPG