St. Joseph, Missouri 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

023
FXUS63 KEAX 061122
AFDEAX

Area Forecast Discussion
National Weather Service Kansas City/Pleasant Hill MO
622 AM CDT Sun Sep 6 2026

...12z Aviation Update...

.KEY MESSAGES...

- Hazardous / prolonged heat continues, with broader relief mid-late
week.

  - Extreme Heat Warning remains in effect through 8 PM for
    Kansas City Metro and immediately surrounding counties.

  - Additional short-duration heat headlines may be possible
    Tuesday as renewed heat briefly surges back across Missouri.

- A SPC Marginal Risk (Level 1 of 5) for severe storms across
  much of the area. Main concerns for damaging wind gusts and
  hail.

&&

.DISCUSSION...
Issued at 334 AM CDT Sun Sep 6 2026

Summary:

The large scale pattern evolution across CONUS remains a generally
broken record, with continued high confidence in its evolution over
the next few days. Just peek the LREF 500mb spreads for confirmation
in that regard. The existing Omega Block pattern will finally begin
to break down later today and into the work week, but substantial
and widespread relief from the existing heat is unlikely before mid-
week. In fact, a brief resurgence of heat is expected Tuesday. In
the more immediate, chances for showers and storms remain today,
including the potential for a few strong to severe and even some
localized heavy rainfall.

Heat and Eventual Relief:

With the mid-level ridge entrenched over central CONUS, the immediate
area unsurprisingly remains very quiet at the moment. The advertised
cool front has made its way into and across much of the CWA, as seen
by the light E to NE winds. Unfortunately for western areas of the
CWA though is that notable relief (cooler temps and lower dew
points) remain displaced further east. In fact, there is actually a
ribbon of enhanced dew points across the state currently with the
drier airmass yet back into Illinois. This will help, to some
degree, set the table for shower/storm chances later today, but more
on that in a minute.

The large surface high responsible for the easterly winds will
continue to drop into the Great Lakes Region, but given its position,
remains unexpected to push much additional relief across the state
as it should effectively stall in/around the Kansas-Missouri border.
This will result in temperatures today ranging from the upper 80s to
low 90s in NE Missouri to more of the same mid-upper 90s to around
100 for western and central Missouri and heat index values
approaching 105 to 110. Monday temps may be a couple degrees cooler,
but still seasonally well above normal, as the easterly winds
struggle to provide much tangible temperatures or dew point relief
beyond eastern Missouri. As the Omega Block breaks down, the mid-
level ridge shifts back eastward and begins to flatten, heat does
briefly surge back on Tuesday when 850mb temps peak. That may yield
yet one more day in the mid-upper 90s to 100 for much of the CWA.
Given the above, Extreme Heat Warnings remain for areas around/south
of Highway 36 through today/Sunday and in/around the Kansas City
metro through Tuesday. An additional short duration headline for
areas outside of the Kansas City metro counties may be considered
for Tuesday.

By Wednesday, the western CONUS cutoff low will have tracked into
the Canadian Plains, flattening the mid-level ridge. Its attendant
surface low will have pushed a cold front across the Northern to
Central Plains, likely to approach northern Missouri by Wednesday
morning. There remains a little uncertainty in timing and how
quickly it pushes southward across the state, which may result in a
bifurcated CWA when it comes to highs Wednesday. Regardless, by
Thursday more seasonable temperatures are anticipated for most,
while southern areas toward central Missouri may remain a few
degrees above normal. Southerly winds return to end the week into
the weekend, likely to bounce temperatures back warmer a few degrees
but not to the extent we have experienced of late.

Shower and Storm Chances:

For today, an interesting evolution in CAM guidance overnight and
early this morning. HRRR/RAP guidance has tended to scale back the
area coverage and potential for air-mass convection this afternoon.
Now largely relegating those opportunities just W and SW of the CWA.
This appears to be at least partially in response to anticipated
cloud cover overspreading the area from existing Nebraska
convection, which would temper peak mixing. Recent HRRR runs depict
more cloud cover over eastern Kansas than is reality, areas
in/around KC Metro may yet see some air mass thunderstorms. Any such
storms would be within an environment characterized by weak wind
profiles and sizable inverted-V (large DCAPE) profiles. This should
yield a primary threat for strong to damaging winds from
evaporatively enhanced downdrafts and brief non-severe hail during
peak heating. Additionally, the aforementioned Nebraska convection
is expected to continue into Iowa and given the position of the mid-
level ridge axis and CAPE gradient, may drift down into northern
Missouri. Recent CAM trends suggest much of the activity remains in
Iowa given the more E to ESE deep layer sheer/steering profiles, but
cannot rule it out especially should a cold pool/outflow move into
the area. Damaging winds would likely remain the primary threat, but
depicted better deep (speed) shear could allow for a severe hail
threat as well. There is an SPC Day 1 Marginal Risk for severe
storms given all of the above. There is also a WPC Excessive
Rainfall Slight Risk that noses into NW Missouri, which would rely
on slow moving and/or training area of storms.

Another opportunity for precipitation moves through the area mid-
week, with the cold frontal passage. While shear profiles appear
supportive of organized convection, frontal strength and timing will
play a factor in any strong/severe potential. For now, suffice it to
say additional shower and storm chances are anticipated during this
time frame.

&&

.AVIATION /12Z TAFS THROUGH 12Z MONDAY/...
Issued at 617 AM CDT Sun Sep 6 2026

VFR conditions prevail to begin the TAF period, but the
potential for non-VFR conditions enters the conversation this
afternoon / after around 20z and may continue to around 06z
before subsiding. Guidance continues to grapple with the
coverage of any air mass type storms, but has suggested those
chances are primarily relegated W and SW of the TAF sites. This
would would turn primary chances for thunderstorms to
progression of current activity or outflows from Nebraska (and
eventually Iowa). Given the lingering uncertainty in coverage,
have opted for PROB30 mentions at all sties. Otherwise winds
remain out of the E to SE up to around 10 kts daytime and
through the remainder of the period.

&&

.EAX WATCHES/WARNINGS/ADVISORIES...
MO...Extreme Heat Warning until 8 PM CDT Tuesday for MOZ028-029-037-
     043-053.
     Extreme Heat Warning until 8 PM CDT this evening for
     MOZ020>022-030-031-038>040-044>046-054.
KS...Extreme Heat Warning until 8 PM CDT Tuesday for KSZ025-057-060-
     103>105.
     Extreme Heat Warning until 8 PM CDT this evening for KSZ102.

&&

$$

DISCUSSION...Curtis
SHORT TERM...
LONG TERM...
AVIATION...Curtis