St. Joseph, Missouri 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

886
FXUS63 KEAX 221740
AFDEAX

Area Forecast Discussion
National Weather Service Kansas City/Pleasant Hill MO
1240 PM CDT Wed Jul 22 2026

.KEY MESSAGES...

- Cooler conditions through Friday, with high temperatures in
  the upper 70s to mid-80s.

- Several rounds of rainfall chances through the end of the
  week, with widespread rain chances peaking at 70-90% Thursday
  night into Friday. Heavy rainfall and flooding is a concern,
  with a Slight (Level 2 of 4) Risk of Excessive Rainfall
  Thursday night into Friday.

- Temperatures return to the 90s this weekend, with 100+ degree
  heat indices potentially making a comeback as well.

&&

.DISCUSSION...
Issued at 1240 PM CDT Wed Jul 22 2026

Clouds and a few light showers over northwest Missouri this
morning from a decaying MCS over Nebraska crossing over into our
area. Northerly winds are advecting in drier, milder conditions
making it feel very pleasant outside. Looking at the broader
upper-level pattern, ridging over the northern Rockies and
Inter-Mountain West has led to northwesterly flow over the
Northern Plains into eastern Kansas and Missouri today.
Shortwaves riding down the east side of this ridge will lead to
a fairly active pattern through the end of the week.

Today, expect light showers to stay confined to northwest
Missouri near and north of St Joe. Many echoes on radar may not
reach the ground due to fairly dry air in the boundary layer
toward the surface. Temperatures will stay seasonably mild this
afternoon with highs in upper 70s north to mid 80s across our
far southern counties. May still see some areas with higher
humidity, mainly near agricultural fields, leading to slightly
higher heat indices. The greater impact today is from smoke as
the jet pulls smoke from wildfires across the Pacific Northwest
and northwest Canada into the central US leading to mostly just
hazy skies. Could see air quality degrade again overnight
tonight as the nocturnal inversion sets up potentially pulling
some of that smoke down toward the surface.

Another shortwave riding down the east side of the persistent
ridge to our west will develop showers and storms over south-
central Nebraska and north-central Kansas later tonight bringing
mostly just showers into our area Thursday morning. The CAMs are
in fairly good agreement in coverage and timing of these showers
with soundings showing almost no instability as they arrive
around 7-8AM Thursday morning. These do look likely to linger
through the morning into at least the early afternoon, so have
brought down temperatures a few degrees from earlier forecasts.
Depending on how long cloud cover and showers linger, we could
still be too warm. Rainfall amounts on Thursday should be mostly
light, around 0.25" or less.

Thursday night into Friday we`ll see a more substantial
shortwave move in, aiding in the amplification of the low-level
jet oriented across eastern Kansas into western Missouri. This
will advect in a greater amount of moisture as this system
arrives with PWATs increasing to around 2" by Friday morning,
increasing to around 2.4" by Friday afternoon. Both these values
are significantly higher than even the 90th percentile for
climatology indicating rainfall from this system will be very
efficient with widespread rainfall totals around 1.5 to 2 inches
likely across much of northern Missouri Thursday night into
Friday. The NBM shows a swath of 50-60% chance for rainfall
amounts in excess of 2 inches from just north of St Joe along
and north of highway 36. WPC has most of our area under a
"Slight Risk" (level 2 of 4) for excessive rainfall Thursday
night into Friday.

Going into the weekend, temperatures will start to climb once
more as southwesterly flow continues across our area with the
western ridge shifting eastward building into the Central
Plains. Expect a return of very hot and humid conditions with
heat indices getting back above 100 degrees starting Saturday
across our southern counties. This will spread across our entire
area on Sunday with heat indices of 100 to 115 possible Sunday
and Monday. I guess we are getting close to August... Monday
night into Tuesday a nocturnal MCS may bring some relief with
the return of northwesterly flow.

&&

.AVIATION /18Z TAFS THROUGH 18Z THURSDAY/...
Issued at 1148 AM CDT Wed Jul 22 2026

VFR conditions should prevail through the TAF period. Winds out
of the north-northeast this morning will be shifting more
easterly overnight tonight with rain moving into the KC Metro
terminals starting around 13Z. Lesser chance (30%) at KSTJ
starting around 13Z as well. -SHRA to continue on and off
through at least 18Z Thursday with a slim chance (15%) for
-TSRA.

&&

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

&&

$$

DISCUSSION...McCoy
AVIATION...McCoy