St. Joseph, Missouri 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

290
FXUS63 KEAX 041910
AFDEAX

Area Forecast Discussion
National Weather Service Kansas City/Pleasant Hill MO
210 PM CDT Fri Sep 4 2026

.KEY MESSAGES...

- Hazardous heat continues. An Extreme Heat Warning remains in
  effect areawide until 8 PM Saturday. Areas along and south of a
  line from St. Joseph, MO to Boonville, MO will remain under a
  Extreme Heat Warning until 8 PM Tuesday.

- Low-end chances (20-30%) for rain Sunday into Monday morning,
  generally across northern Missouri. Next rain chances arrive
  midweek.

&&

.DISCUSSION...
Issued at 201 PM CDT Fri Sep 4 2026

No significant changes to the forecast were made in this cycle.
Deterministic and ensemble guidance alike continue to be locked into
a persistent upper-level ridge through about midweek next week. As
such, heat has remained the primary forecast concern for the time
being. A trough over the Pacific Northwest will be one to watch as
the thermal ridge erodes and the trough slides to the east.
This may present a few opportunities for rain midweek next week
but more on that later...

12Z upper-air observations clearly portray the ridge sprawled over
the southern and central CONUS with a largely sedentary low over the
Pacific Northwest and another in the vicinity of Newfoundland and
Labrador. Our position relative to this Omega-block will allow
temperatures to once again soar into the mid/upper 90s areawide,
with high temperatures in our far south potentially reaching triple
digits and heat index values around 105. With little to no change in
the pattern on Saturday, expect similar conditions, just maybe a few
degrees warmer than today. Late Saturday night, a backdoor cold
front is expected to begin moving into the northeast portion of the
CWA and continue sliding south throughout the day on Sunday. It is
possible that some showers may be able to develop in the vicinity of
this boundary so have bumped PoPs into the 20-30% range across
northern Missouri and into the 10-20% range south of US-36 Sunday
afternoon and evening. Counties generally along and north of the
Grand River will have the Extreme Heat Warning end Saturday night as
slightly cooler conditions in the low/mid 90s are expected on Sunday
with the passage of the backdoor cold front and associated cloud
cover/rain chances. South of this corridor, little reprieve is
expected on Sunday as the front is not anticipated to move through
the south and western portions of the CWA until after peak heating
so the Extreme Heat Warning remains in effect along and south of the
Missouri River until Tuesday evening. More marginal conditions are
expected on Monday behind the backdoor cold front, but several
locations are still expected to reach hazardous heat thresholds,
especially those around the KC Metro area and in east-central KS and
west-central MO.

The deamplifying ridge will be hurried west ahead of the then
progressive PNW low sometime midweek. Currently, forecast
temperatures and heat index values on Wednesday would qualify for an
extension of the Extreme Heat Warning. However, there is substantial
uncertainty regarding the timing of the attendant cold front that is
set to sweep across the Plains. The most recent guidance suggests
that this could occur as early as Tuesday night or as late as
Wednesday night. Though an extension was considered during this
forecast cycle, uncertainty was far too high for one to be issued.
Trends will be monitored closely in the days ahead to make this
determination. Rain opportunities may also arrive with this cold
front, but again, there is a lack of precision when it comes to
timing so have retained about 20-30% 6-hourly PoPs from
Wednesday morning into Friday morning to account for
precipitation potential from the cold front as well as any
shortwaves that ripple through a comparatively more zonal
pattern.

&&

.AVIATION /18Z TAFS THROUGH 18Z SATURDAY/...
Issued at 1221 PM CDT Fri Sep 4 2026

VFR conditions will continue throughout the TAF period at each site.
Winds are expected to remain out of the SW around 10kts, with gusts
up to 15kts. Gusts will diminish throughout the evening, with a
directional shift out of the S. Clear skies are expected to
persist during the afternoon, with a slight increase in clouds
after sunset on Friday.

&&

.EAX WATCHES/WARNINGS/ADVISORIES...
MO...Extreme Heat Warning until 8 PM CDT Tuesday for MOZ020>022-
     028>031-037>040-043>046-053-054.
     Extreme Heat Warning until 8 PM CDT Saturday for MOZ001>008-
     011>017-023>025-032-033.
KS...Extreme Heat Warning until 8 PM CDT Tuesday for KSZ025-057-060-
     102>105.

&&

$$

DISCUSSION...Macko
AVIATION...Bjork