St. Joseph, Missouri 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

957
FXUS63 KEAX 190953
AFDEAX

Area Forecast Discussion
National Weather Service Kansas City/Pleasant Hill MO
453 AM CDT Sun Jul 19 2026

.KEY MESSAGES...

- Isolated to scattered showers and non-severe thunderstorms
  this afternoon, especially between Highway 36 and Highway 50
  (35-55% chances). Heavy downpours will be possible with any
  storms that stay over the same areas for more than an hour.

- Heat Advisory in effect for northeast Kansas and portions of
  western and central Missouri from 1 PM to 9 PM on Monday, with
  anticipated heat indices of 100-110 degrees.

- Monday night into Tuesday will see a 20-40% chance of storms
  in north-central Missouri as a line of storms advances south
  along an incoming cold front.

- Additional chances for showers and thunderstorms are forecast
  Wednesday night into Thursday morning (15-50% chance) and
  Thursday night into Friday morning (35-60% chance).

&&

.DISCUSSION...
Issued at 330 AM CDT Sun Jul 19 2026

Current Conditions & Synoptic Overview:
Surface high pressure sits over the Great Lakes area early this
morning, with a quasi-stationary cold front draped across
northern Missouri, generally along a line from Nebraska City, NE
through Chillicothe, MO towards Effingham, IL as of 3AM Sunday.
Ridging at 500mb and above is broad across the central CONUS,
but 00Z upper air data shows there are two semi-distinct yet weak
centers of high pressure within the flow at 700mb and below.
One area of 700mb high pressure is centered over central
Nebraska, and the other is over the Gulf Coast near Houston. As
a consequence of this, Missouri is within a deformation zone,
with a line of weakly organized showers and storms visible on
radar across southern Missouri early this morning where the LLJ
is enhancing isentropic ascent.

Today:
Isolated to scattered convection will continue through the
remainder of the early morning hours, especially the far
southwest portion of the forecast area. As the nocturnal LLJ
wanes, precip chances begin to wane south of Highway 50. PoPs
begin to increase again after noon as instability increases,
with the weak convergence along the front expected to be enough
to re-initiate scattered showers and storms. If storms are able
to develop organized cold pools, there could be additional
development along any outflow that results, increasing overall
coverage. There is also a risk of heavy downpours and localized
flooding with any mature/longer-lived storms, though widespread
heavy rainfall is not expected due to the scattered nature of
the storms. Highest PoPs (35-55%) this afternoon are expected
between the US Highway 36 and US Highway 50 corridors, which is
where the front is expected to generally remain parked. However,
would not be surprised to see an isolated diurnally-driven pop-
up shower or two outside of this area, so most of the area has
at least a 15% PoP for this afternoon.

Otherwise, highs in the low to mid-90s this afternoon, with heat
indices in the 90s behind the front in north-central Missouri
and 100-105 degrees elsewhere. Areas near Kirksville will begin
to get caught in the western periphery of the smoke plume
that`s been plaguing the upper Great Lakes region from wildfires
in the Boundary Waters of northern Minnesota into this
afternoon/evening as well. This could lead to temporarily
decreased air quality indices and hazier skies, but no
significant impacts are expected from the smoke, and smoke will
not reach as far west as the Kansas City metro.

Heat Advisory Monday, Still Hot Most Places Tuesday Too:
Southwesterly 850mb winds bring warmer, moister air into the
southern and western portions of the forecast area on Monday,
with the stationary front expected to pivot and lift northeast
as a warm front during the day on Monday. Temperatures should
rise further into the mid- to upper 90s behind this front, with
dew points increasing into the low to even mid-70s. This brings
our heat indices as high as 105-110 in the western and southern
portions of the area, where a Heat Advisory has been issued from
1 PM to 9 PM on Monday. Much of the area is in a Major Heat Risk
(Level 3 of 4) category, indicating that the expected level of
heat affects anyone without effective cooling or adequate
hydration.

While the Heat Advisory does not currently continue through
Monday night or into Tuesday, we will be monitoring for the need
to extend the Advisory in time for areas south of I-70, where
heat indices are expected to be between 100-110 degrees again on
Tuesday. Current confidence is not high enough in heat index
values and placement of potential 105-110 degree heat indices
to extend into Tuesday as a result of questions about the
influence of convection on Monday night into Tuesday and the
speed at which the cold front will move through the area on
Tuesday. However, as confidence increases in the speed and
placement of the frontal passage on Tuesday and the impact of
those features on individual locations` temperatures, we will
continue to reassess whether additional Heat Advisory issuance
will be needed in our furthest south counties. It is also worth
noting that Monday night into Tuesday, ahead of the frontal
passage, that low temperatures will be quite toasty, only
cooling into the upper 70s overnight, so nighttime recovery from
the heat will be quite limited in most areas.

Storm Chances Monday Night Into Tuesday:
A shortwave trough will begin to cut into the northern extent of
our ridge on Monday and strengthen as it pushes southeast into
the upper Midwest, with an organized line of storms expected to
develop in Iowa by the evening hours and grow upscale along the
cold front during the overnight hours. Confidence that this
activity will develop as far south along the front as north-
central Missouri is generally low, with a 20-40% PoP confined to
the far northeast corner of the CWA, but the expected storm mode
for any development along the front is bowing clusters, which
would carry the risk of organized severe wind gusts. As such,
there is a sliver of north-central Missouri included in the
Marginal (Level 1 of 5) Risk for severe weather by SPC to
account for the scenario where storms expand south into Missouri
very late Monday night into early Tuesday morning.

Pattern Shift Midweek:
Once the initial shortwave trough impinges on the persistent
high pressure that`s been parked over the Intermountain West on
Monday, it opens the door for several additional pulses of
shortwave energy to move across the area through the remainder
of the week. There is still considerable uncertainty in how the
pattern will unfold after the first system of the week occurs,
but confidence is high that a northwesterly flow will advect
much cooler, drier air into the region. Temperatures appear to
be lowest on Thursday, with highs in the low to mid-80s and dew
points even in the upper 50s to low 60s! Refreshing, after the
hot and muggy conditions we start the week with.

Guidance continues to point towards one or more MCSs moving
through the region Wednesday-Friday, with a slight upward trend
in PoPs for Wednesday and Thursday nights compared to previous
forecast cycles. We have a 15-50% rain chance for Wednesday
night into Thursday morning in western Missouri/eastern Kansas
and a widespread 35-60% PoP on Thursday night into Friday
morning in association with this potential activity. Details
beyond that are limited, so stay tuned for updates as the
mesoscale details become more clear.

&&

.AVIATION /06Z TAFS THROUGH 06Z MONDAY/...
Issued at 1050 PM CDT Sat Jul 18 2026

VFR conditions are expected to prevail through 18Z/Sunday.
Scattered showers and thunderstorms are expected after 18Z
Sunday. Included prob 30 storm mention late tomorrow (20-24 Z)
for KC Metro sites. Storms are expected to weaken and dissipate
with sunset.

&&

.EAX WATCHES/WARNINGS/ADVISORIES...
MO...Heat Advisory from 7 PM to 9 PM CDT Monday for MOZ001-002-
     011>013-020>022-028>031-037>040-043>046-053-054.
KS...Heat Advisory from 7 PM to 9 PM CDT Monday for KSZ025-057-060-
     102>105.

&&

$$

DISCUSSION...Camden
AVIATION...BT