St. Joseph, Missouri 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

672
FXUS63 KEAX 132042
AFDEAX

Area Forecast Discussion
National Weather Service Kansas City/Pleasant Hill MO
342 PM CDT Tue Oct 13 2026

.KEY MESSAGES...

- Strong/Severe thunderstorms expected during the evening/early
  overnight tonight. Initial hazards include large hail and
  damaging winds before evolving into a damaging wind threat.

- Excessive rainfall also expected during the evening/overnight,
  with a Flood Watch encompassing the KC Metro and areas
  south/southeast of I-70.

- Continued chances for precipitation during the day Wednesday
  and into Thursday.

- Temperatures cool down Friday and Saturday, with increasing
  likelihood to meet frost/freeze criteria across northern MO
  (40-60%).

&&

.DISCUSSION...
Issued at 333 PM CDT Tue Oct 13 2026

The cold front from yesterday afternoon has slowly progressed
southeastward, and has stalled out from Salina, KS northeastward to
about Peoria, IL. South of this boundary, temperatures have climbed
into the high 80s/low 90s, with dewpoints residing in the low 70s.
This has increased instability along/south of the boundary to about
2000-2500 J/kg, with effective bulk shear residing around 35-40 kts.
This unstable, sheared airmass will see influence from a shortwave
and strengthening LLJ later into the evening, providing synoptic-
scale lift and invigorating the development of organized
thunderstorms. CAM guidance throughout the day has indicated an
initial discrete mode with storms as they fire up along the
boundary, before congealing into an MCS by the overnight period.
More recent guidance has been varied with the exact trajectory of
the MCS during the overnight period, but generally has placed it
along/south of the I-70 corridor, following the boundary/CAPE
gradient. With initial discrete storm modes, there is an associated
hazard for large hail/damaging winds. There is an additional concern
for isolated tornadoes, especially if storms develop near/along the
boundary or within the proximity of the LLJ. After these initial
discrete storm modes, damaging wind will become the primary hazard
with the congealing MCS.

An additional concern with storms overnight will be excessive heavy
rainfall. PWATs of ~1.7 inches has developed across north-central MO
throughout the day, with guidance indicating PWATs of up to 2 inches
by the evening. Additionally, moisture transport resides just
parallel/at a slight angle to the surface boundary, with a moist
vertical profile in place. Although storms will remain progressive
through the evening with strong cloud layer winds and
upshear/downshear vectors, efficient storms training over the same
locations will enhance concerns for flooding through the overnight,
especially with dry antecedent conditions making it harder for soils
to saturate right away. The current Flood Watch was expanded
northward to include counties within the KC Metro area, as guidance
has also increasingly trended towards higher rainfall accumulations
during the overnight period (~2-4 inches in the HREF LPMM by early
Wednesday).

The severe threat is expected to diminish through the overnight as
the environment becomes more capped and synoptic scale forcing
diminishes. Continued moist advection over the boundary will keep
light rain across the forecast area during the early morning, before
it looks to also diminish by the afternoon as the boundary sags
further south. CAMs have been varied with their resolutions of
activity during the day tomorrow, with recent runs either placing
additional scattered showers/storms across the area while others
keep the forecast area dry for most of the day into the evening.
Currently, PoPs for the day reside around 30-50% to account for the
additional moist advection over the boundary. The primary corridor
for continued severe hazards during the day tomorrow resides south
of the boundary, which looks to remain just south of our forecast
area. With uncertainty regarding the evolution of an ongoing
flooding concern, have chosen not to extend the Flood Watch in time
across the forecast area, with greater opportunities for excessive
rainfall continuing to the south and west of the forecast area.

By early Thursday, the upper-level trough over the Intermountain
West will lift towards the Great Lakes, and continue precipitation
chances through synoptic-scale ascent with dCVA and strong low-level
WAA. There are indications of an excessive rainfall threat with this
next round of precipitation, with HREF LPMMs coming in a bit hot in
swaths of high accumulations during that timeframe (~1-3 inches).
However, this threat looks to be relatively short-lived as the
trough quickly lifts towards the Great Lakes by the evening. As this
trough and its attendant surface low lift off towards the
northeast, a cold front will sweep southeast across the forecast
area and synoptic high-pressure will build in from the west.
The cold frontal passage will help bring down temperatures to
more seasonable temperatures, with high temperatures in the high
50s/low 60s during the daytime. Building high pressure behind
the surface low will enhance the pressure gradient going into
Friday, and lead to breezy conditions not too dissimilar from
this past Monday (gusts up to 30- 35 mph possible). Building
high pressure will also lead to synoptic- scale subsidence,
keeping conditions dry going into the weekend. Enhanced
radiational cooling under clear skies will allow temperatures to
drop into the 30s overnight, putting areas of northern
MO/northeastern KS under their first frost conditions since late
March. As surface high pressure slides off towards the Ohio
Valley and mid-level ridging builds in from the west, northerly
winds will turn out of the south, prompting a warm up of high
temperatures into the 70s throughout the weekend. Model guidance
increasingly deviates in the synoptic pattern by the start of
next week, leading to decreased confidence in the potential for
precipitation by Monday. However, continued southerly flow and
the positioning of the ridge axis over the central CONUS
maintains thoughts that temperatures will continue to warm
through the end of the forecast period.

&&

.AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/...
Issued at 1233 PM CDT Tue Oct 13 2026

VFR through at least 0z tonight. Anticipating SHRA/TSRA to
impact terminals overnight, with the primary window for TS being
around 0-4z. Afterwards, anticipating the presence of -SHRA/SHRA
through at least 14-16z tomorrow. Boundary currently situated
over the KC Metro area will sag southward through the night,
shifting winds out of the north. With the passage of the
boundary, residual moisture from precipitation, and cooling
temperatures, expecting the degradation of visibilities/ceilings
to IFR late in the period.

&&

.EAX WATCHES/WARNINGS/ADVISORIES...
MO...Flood Watch from 7 PM CDT this evening through Wednesday
     morning for MOZ028-029-037-043>045-053-054.
KS...Flood Watch from 7 PM CDT this evening through Wednesday
     morning for KSZ057-060-103>105.

&&

$$

DISCUSSION...SPG
AVIATION...SPG