St. Joseph, Missouri 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

040
FXUS63 KEAX 021126
AFDEAX

Area Forecast Discussion
National Weather Service Kansas City/Pleasant Hill MO
626 AM CDT Thu Jul 2 2026

...Updated Aviation Discussion...

.KEY MESSAGES...

* Hazardous heat continues. Heat indices in the 100-105 F range are
  expected through Friday. An Extreme Heat Warning Remains in effect
  until Friday evening.

* Low chances (~20-30%) for showers and storms through the end of
  the week, mainly across north and northwest Missouri in the
  evening and overnight hours.

* Scattered storms possible (40-50% chance) Saturday, July 4th, in
  the afternoon and evening. There is a Marginal Risk (Level 1 of 5)
  of severe weather.

* Off-and-on rain chances (20-30%) continue into early next week
  with slightly cooler temperatures (low 90s) and lower heat
  indices (95-100 F).

&&

.DISCUSSION...
Issued at 323 AM CDT Thu Jul 2 2026

Ridge influence will remain the status quo for at least another
couple of days while the upper-level trough in the West attempts to
suppress the oppressive heat regime in the central and eastern
portions of the CONUS. Guidance points to a collapse of this ridge
over the weekend following a series of shortwaves ejected by the
western trough. Zonal flow will return for a number of days, and
while the precise number of days is unclear, the expectation is for
ridging to rebuild over the Four Corners around midweek next week.

The Extreme Heat Warning will remain in effect through Friday
evening. While heat indices have likely topped out already,
confidence remains high in widespread 100-105 heat indices and poor
overnight recovery with minimum heat indices in or near the 75-85 F
range. EFI continues to show that the ongoing heat event is unusual
compared to reforecast climatology. The latest ENF forecast for 24-
hour mean temperature on July 2, for example, produced an EFI of 56%
(previous runs for the same date had EFIs between 52-61%). Per EFI,
we are indeed in the midst of an anomalous heat event. As we move
past the weekend, we`ll begin to fall out of the "unusual" category.
That said, it will still be toasty (temperatures in the low 90s and
heat indices in the 95-100 F range).

Precipitation chances also gradually increase as we turn our
attention toward the weekend. The upper-level trough mentioned
earlier has been continuously sending shortwave disturbances
sprawling across the Great Plains, helping support convection on the
periphery of the ridge. So far, the vast majority of this activity
has remained north, but with the synoptic pattern expected to
flatten out in the coming days, shortwave disturbances traversing
the flow will be less likely to experience northeastward
"deflections" due to the upper-level ridge. This becomes most
apparent late Friday/early Saturday as a shortwave ejected over the
Northern Rockies intensifies across the Upper Midwest, helping
stifle the ridge and bring zonal flow back to the Central Plains.
Though probabilities remain low (only a 20-30% chance at this time),
this impulse will bring the first opportunity for scattered showers
and storms late Friday evening into early Saturday morning. While
there will be plenty of instability available, forecast soundings
depict quite an impressive capping inversion. Moreover, the lack of
shear locally will limit organized updraft development/sustenance.

A second, slightly higher probability (40-50%) for scattered
showers/storms comes Saturday afternoon/evening as a
shortwave/vortmax runs across the Plains. Ample instability will
once again be available, with forecast soundings now showing a
gradual erosion of the cap over the course of the day. Deep-
layer shear also looks to improve in the late evening/overnight
hours. While the parameter space appears to be conducive of
convection, the modes of ascent are unclear beyond PVA
associated with the shortwave. Focus for convection looks to
come down to mesoscale features not yet apparent...perhaps a
residual outflow boundary left from storms in the morning? In
that case, uncertainty for the Saturday evening threat is
compounded by the uncertainty associated with the morning
threat.

Off-and-on rain chances will continue through the early
part of next week, but since the forecast is especially low
confidence at this range, this has yielded only about a 20-30%
chance on any given day.

&&

.AVIATION /12Z TAFS THROUGH 12Z FRIDAY/...
Issued at 620 AM CDT Thu Jul 2 2026

High clouds are streaming over northwestern Missouri and
northeastern Kansas. Winds gusts will pick up early afternoon
around 18-22kts and then relax with sunset. There is a low
chance for a shower or storm in far northwestern Missouri today
and this evening.

&&

.EAX WATCHES/WARNINGS/ADVISORIES...
MO...Extreme Heat Warning until 9 PM CDT Friday for MOZ001>008-
     011>017-020>025-028>033-037>040-043>046-053-054.
KS...Extreme Heat Warning until 9 PM CDT Friday for KSZ025-057-060-
     102>105.

&&

$$

DISCUSSION...Macko
AVIATION...Wilson