St. Joseph, Missouri 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

559
FXUS63 KEAX 120740
AFDEAX

Area Forecast Discussion
National Weather Service Kansas City/Pleasant Hill MO
240 AM CDT Mon Oct 12 2026

.KEY MESSAGES...

- Dry, breezy weather and enhanced fire weather concerns are
  expected today.

- Near, or above, record heat continues today and Tuesday.

- Strong to severe storms are possible Tuesday
  afternoon/evening. The primary threats are damaging winds and
  marginally severe hail.

- Shower/storm chances increase (75-95%) Tuesday evening into
  Wednesday morning, lasting through Thursday.

- Temperatures cool down into the upper 50s and low 60s by the
  end of the week.

&&

.DISCUSSION...
Issued at 240 AM CDT Mon Oct 12 2026

A 500-hPa analysis shows mid-level ridging present over the
central CONUS, with a high amplitude trough situated over the
western CONUS and a shortwave along the East Coast. This pattern
will continue to support near, or above, record temperatures
today, with highs expected to be in the upper 80s and low 90s.
At the surface, a frontal boundary is draped from the Upper
Great Lakes back to a low pressure system that is developing in
northeast CO and the NE panhandle. A broad area of high pressure
is situated over the Gulf Coast. A tight pressure gradient
between these two surface features will allow breezy (10-15 mph)
southwesterly winds to continue through the early morning hours
this morning across northern MO and northeastern KS with gusts
up to 25 mph possible at times. The low pressure system is
expected to move northeast through the day today, further
tightening the pressure gradient and allowing winds to increase
to 15-20 mph by the afternoon with gusts up to 35 mph. While the
winds alone create elevated fire weather concerns given the dry
antecedent conditions, afternoon RHs will only fall to the
35-50% range, so Red Flag Criteria is not expected to be met
today.

As the low pressure system moves towards the Upper Great Lakes
today, it will push a cold front across NE and IA. This front is
expected to reach northwest MO this evening/overnight. The nose
of a 30-35 kt LLJ will reach into southeastern NE and
northwestern MO overnight, which may provide enough lift for a
few showers to form along or behind the front through the early
morning hours.

The progression of the front is expected to slow on Tuesday,
with the front becoming nearly stationary across northern MO.
Model guidance remain in poor agreement on where exactly this
stall will happen, resulting in large spreads in forecast
temperatures on Tuesday. However, the general consensus is for
areas south of the front to be in the low 90s (making Tuesday
the hottest day of this heat wave), while areas north of the
front will see temperatures in the low-to-mid 80s. Southerly
surface flow will also continue on Tuesday bringing Gulf
moisture into the region. Dew points are expected to climb into
the upper 60s and low 70s by Tuesday afternoon, which will
actually bring heat indices in the upper 90s to near 100F into
play, which is mind-boggling for mid-October.

Another result of the influx of boundary layer moisture will be
the development of 1000-2000 J/kg of MLCAPE south of the frontal
boundary Tuesday afternoon/evening. This will come in
conjunction with 40-50 kts of deep layer shear. To the west, a
mid-level trough will slide east over the Great Basin and lee
cyclogenesis will occur in southeastern CO. With better synoptic
support focused to the west of the local area, CAM guidance
indicates that convective initiation should occur across central
KS and areas south by mid-afternoon. The local area will be
capped through much of the afternoon, however, the combination
of diurnal heating and increasing synoptic support should allow
the cap to erode through the day and convection appears likely
along the frontal boundary by late afternoon/early evening. Mid-
level lapse rates are not overly impressive (6.5-7 C/km),
however, given the parameter space previously outlined, strong
to severe storms appear possible, with the primary threats being
damaging winds and hail up to 1" in diameter. This thinking
aligns with the SPC Day 2 outlook, which outlines eastern KS and
western MO in a Slight (Level 2 of 5) Risk with the remainder
of northern MO in a Marginal (Level 1 of 5) Risk.

Continued ascent along the frontal boundary Tuesday night will
lead to the development of widespread showers and storms by
early Wednesday morning, lasting into Thursday. The presence of
this precipitation makes the convective forecast for Wednesday
a little uncertain. Model guidance indicates that at least some
instability will be present, with shear values remaining
elevated, so it seems as though at least some severe threat
exists Wednesday afternoon/evening, though, the best parameter
space should be on the southern periphery of the showers. SPC
has outlined the far southern portion of the CWA in a Day 3
Marginal (Level 1 of 5) Risk, which matches this thinking.

Though model guidance diverges on the handling of the upper
trough beyond Thursday, there is agreement that a cold front
will sweep across the Central Plains Thursday afternoon/evening
and high pressure will build in from the northwest bringing a
cool down to the region. The current forecast calls for highs
in the upper 50s and low 60s on Friday and Saturday with low
falling into the 30s on Friday night.

&&

.AVIATION /06Z TAFS THROUGH 06Z TUESDAY/...
Issued at 1039 PM CDT Sun Oct 11 2026

VFR will continue through the next 24 hours, with breezy
conditions remaining the primary aviation concern. South winds
around 10 to 15 kt with occasional gusts to 20 kt or so will
continue overnight. Southwesterly LLWS will prevail at STJ,
where surface speeds/gusts may be more reduced overnight. Winds
will increase and become persistently gusty on Monday, with
directions becoming slightly more southwesterly. Gusts to 30 kt
are possible at times during the afternoon. Winds should slow to
around 10 to 15 kt after 00z Tuesday.

&&

.EAX WATCHES/WARNINGS/ADVISORIES...
MO...None.
KS...None.

&&

$$

DISCUSSION...Carothers
AVIATION...CMS