St. Joseph, Missouri 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

656
FXUS63 KEAX 091143
AFDEAX

Area Forecast Discussion
National Weather Service Kansas City/Pleasant Hill MO
643 AM CDT Wed Sep 9 2026

...12z Aviation Update...

.KEY MESSAGES...

- Hot conditions continue one more day for areas roughly near
  and south of I-70.

  - A Heat Advisory is in effect through 7pm this evening for a
    few counties south of I-70

- Scattered showers and storms drift southward today, including
  the potential for a few strong to severe storms near and south
  of the Missouri River this afternoon and evening. The main
  threat will be for strong and damaging wind gusts.

- Cooler/more seasonal temperatures fully overspread the area by
  Thursday and continues through the weekend and into next week.

&&

.DISCUSSION...
Issued at 336 AM CDT Wed Sep 9 2026

The mid-level ridge that has been in place across the central CONUS
for what seemed like an eternity has effectively flattened. This in
response to the former western portion of the Omega Block lifting NE
into the Northern Plains and Canadian Plains and a trailing mid-
level shortwave rounding its base. The surface low reflection of the
main mid-level feature has pushed a frontal boundary southward into
the region, and has begun to push into/through northern Missouri and
NE Kansas. Given the shallower nature of the boundary, shower and
storm activity is displaced north of the surface front, tied more
closely to the LLJ and 850mb front. While the low levels remain
quite dry, stabilization in the lowest levels and lack of
strong/robust storm cores should severely limit downbursts potential.
The overnight environment really is more conducive to a flooding
threat given the parallel shear/steering flow and moisture
transport. Fortunately, a more scattered nature limits truly short-
duration rainfall and most areas should be able to handle 2.5 to 5
inches of rainfall or more over 3 to 6 hr durations, via RFC FFG.
Areas that saw storms the other day, mainly western Missouri into
far eastern Kansas, may be on the lower end of that range. A slowing
trend to the frontal passage also increases flood potential a tinge.

As just mentioned, recent CAM guidance has continued to slow the
overall frontal progression, now potentially not to the east-west
portions of the Missouri River until 18z. This will potentially
cause a couple of main deviations from the initial forecast. First,
it may yield a window of highs into the mid-upper 90s (yes,
again...) for areas around the KC Metro southward. Northern portions
of that may only see a couple/few hrs of this heat before the front
and/or convection occurs, but southern areas may have a full day of
this. Including heat index values pushing around 105 again. Thus,
there will be a very small Heat Advisory for today. Right now, it
will NOT include the KC Metro considering it may be quite short
duration. The slower progression potentially pulls the strong/severe
storm threat back northward a bit. While SB/MUCAPE depictions are
not wholly different with muddled mid-level lapse rates in place,
the difference becomes more clear when you view point soundings.
Deep inverted-V soundings near/south of the front vs elevated nature
north of. Primarily it would increase the damaging wind gust /
downburst threat. Small hail would remain in play, but organized
storms appear difficult to come by with better shear profiles north,
but the thermodynamic profiles remain fairly poor. Initial storms
would tend to carry the greatest risk before increasing areal
coverage and training storms moisten the low levels. The SPC
Marginal Risk (Level 1 of 5) remains fairly well placed, maybe a
tinge south given recent trends, and is driven solely by wind.

By Wednesday night/overnight this activity shifts further south and
out of the immediate area. And with that... the prolonged heat
officially over for the entirety of the CWA. Highs fall back closer
to seasonal norms with forecast highs in the 80s tending to prevail
through the weekend and into early next week. The next opportunity
for precipitation moves through this weekend Friday night and again
Saturday night as a couple of mid-level shortwaves move through the
more zonal flow. Current deterministic depictions suggest the
potential for a couple rounds of thunderstorm activity. Right now,
highest confidence is just west into Kansas, but would drift into
the area from NW to SE and then W/SW to E/NE respectively. Of casual
note, depending on the evolution the next couple of cycles, this
could also include the potential for flooding potential by Saturday
night/overnight as current depictions show a developing surface low
and the warm frontal position possibly across northern Kansas and
into Missouri somewhere between Highway 36 and I-70 corridors. That
would be on top of anything received Friday night. Plenty of time to
evolve, but would be the next window to watch.

&&

.AVIATION /12Z TAFS THROUGH 12Z THURSDAY/...
Issued at 637 AM CDT Wed Sep 9 2026

A messy TAF period on tap across the sites. Given the scattered
off/on nature of the showers and isolated thunder, difficult to
pin down any kind of true prevailing SHRA/TSRA opportunities. As
such, have opted for mixture of TEMPO and PROB30 to try and
highlight the nature of and the best windows of opportunity.
After 00z, it is possible to have some renewed scattered
activity, but confidence was not high enough and already enough
lines in the TAF, honestly. Latter portions of the period will
see stratus settle in, but kept from dropping the IFR hammer,
MVFR instead, though it may be necessary in subsequent
issuances.


&&

.EAX WATCHES/WARNINGS/ADVISORIES...
MO...Heat Advisory from noon today to 7 PM CDT this evening for
     MOZ045-053-054.
KS...Heat Advisory from noon today to 7 PM CDT this evening for
     KSZ060.

&&

$$

DISCUSSION...Curtis
SHORT TERM...Carothers
LONG TERM...IPC
AVIATION...Curtis