St. Joseph, Missouri 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

218
FXUS63 KEAX 181919
AFDEAX

Area Forecast Discussion
National Weather Service Kansas City/Pleasant Hill MO
219 PM CDT Sat Jul 18 2026

.KEY MESSAGES...

- Isolated to widely scattered thunderstorms (15-30%) are
  forecast this afternoon and early tonight. Another chance
  (20-40%) of storms is forecast Sunday afternoon for locations
  near and south of I-70.

- Elevated heat and humidity levels are forecast today through
  Monday. Peak heat index values of 95-105 are forecast today
  and Sunday, followed by 100-110 values on Monday.

- Additional chances for showers and thunderstorms are forecast
  Wednesday night into Thursday morning (15-30% chance) and
  Thursday night into Friday morning (30-50% chance).

&&

.DISCUSSION...
Issued at 217 PM CDT Sat Jul 18 2026

Across the CONUS early this afternoon, expansive H5 ridging
exists across the Intermountain West and Four Corners region,
while troughing extends NW to SE across the northeast CONUS.
The local area is between these two features in a weak
baroclinic zone.

Isolated to widely scattered (15-30%) pulse convection will
continue to bubble up and down this afternoon. As a cold front
attempts to move into the area from the NE, slightly more
organized, gusty storms could develop this evening around the
Kirksville area, but shear values are very limited even here.
Sunday will see more of the same as the frontal boundary sags
further into NE MO, but convection will be greatest near and
south of I-70. With PWAT values still around 1.9-2.1", locally
heavy rain and flooding issues will be a concern.

Elevated temperature and humidity levels will continue through
early next week. High temperatures today and Sunday will reach
the lower 90s, but humidity levels will increase a bit on Sunday
as moisture pools ahead of the frontal boundary. Peak heat index
values will reach the upper 90s to lower 100s this afternoon,
but more widespread lower 100 values are expected Sunday.

The worst of the heat will be Monday as the ridge to our west
briefly builds east over the region. This will bring high
temperatures in the middle to upper 90s and peak heat index
values of 100-110 degrees are forecast. Will likely need a Heat
Advisory for the western half of the forecast area on Monday,
but will hold off for now due to uncertainty with the eastern
extent of the heat. The ridge will begin to retreat west from
the region on Tuesday. High temperatures will still range from
the mid/upper 90s to upper 80s/lower 90s from SW to NE
respectively. Dew point values will be drawing down on Tuesday,
so the need for additional heat headlines remains uncertain.

The middle to latter half of next week look to be a bit more
active as the region will still be under NW baroclinic flow.
With increasing LLJ activity over the Central Plains, extended
range model guidance is hinting at the potential for multiple
MCS`s to move through the area, first Wednesday PM/Thursday AM
and then again Thursday PM/Friday AM. There is still time for a
lot of adjustments to what is essentially a mesoscale event, so
the best thing to do is stay tuned for updates to the forecasts
in the coming days. Temperatures will be near typical late July
values in the middle to upper 80s for highs and the middle 60s
to lower 60s for lows.

&&

.AVIATION /18Z TAFS THROUGH 18Z SUNDAY/...
Issued at 1215 PM CDT Sat Jul 18 2026

SCT-BKN CU decks with bases between 2500-5000ft generally will
continue to bubble up this afternoon. Isolated showers and storms
will develop during the heat of the day (roughly 18-23z). Satellite
trends show quite a bit of agitated CU over the KC Metro and
southward, so opted to add PROB30 groups for TSRA to MCI, MKC, and
IXD for this period. Winds will be from the SW-WSW around 7-10 kts
this afternoon, becoming S tonight around 3-6 kts. Winds will back
to the S to SE after 16z Sunday, with more diurnal CU development
expected.

&&

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

&&

$$

DISCUSSION...Snyder
AVIATION...Snyder