St. Joseph, Missouri 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

159
FXUS63 KEAX 220454
AFDEAX

Area Forecast Discussion
National Weather Service Kansas City/Pleasant Hill MO
1154 PM CDT Tue Jul 21 2026

...06Z Aviation Update...

.KEY MESSAGES...

- Cooler conditions over the next several days, with high temperatures
  in the upper 70s to the mid 80s.

- Some air quality degradation and haziness is possible midweek as
  smoke from wildfires is pulled into the region.

- Rain and storm chances return Wednesday and continue through Friday.
  Excessive rainfall leading to flooding is the main concern,
  especially Thursday evening into Friday.

&&

.DISCUSSION...
Issued at 205 PM CDT Tue Jul 21 2026

Cooler temperatures are in store for the next several days following
the passage of a cold front this morning. With flow shifting out of
the northwest, additional wildfire smoke from the Pacific Northwest,
British Columbia, and the Northwest Territories will be drawn in via
the jetstream. As clouds continue to dissipate over the course of
the afternoon, the sky may take on a hazy appearance as smoke is
carried southeastward. Air quality reductions will also be possible
as some of the smoke mixes down to the surface with an Adi of around
50 (yellow) late this afternoon and overnight into tomorrow.

Several shortwaves are expected to propel through the region in the
coming days, first during the late morning/early afternoon hours on
Wednesday. Mid-level moisture improves poleside of the ridge
late morning, just in time for the arrival of the vortmax.
Overall, though, northwestern Missouri still looks to be on the
"drier" side of the moisture gradient, especially in the lower
levels. Despite a boost in mid-level moisture, there`s not much
confidence in rain being able to overcome the much drier near-
surface layer. For now, only about a 10-20% chance of rain was
included in the forecast for tomorrow afternoon in far northwest
Missouri.

The next rainfall opportunity arrives late Wednesday evening into
early Thursday morning. Southwesterly flow along the upwind portion
of the ridge coupled with the low-level jet setting up over western
and central Kansas will allow tropical moisture to surge into the
Great Plains. While the best moisture returns are expected over
southern Nebraska, PWATs locally are hovering around 1.5-1.75" which
is roughly within the 75th to 90th percentile of climatology. Even
so, the heaviest rainfall will likely occur west and northwest of
our area of concern. Portions of far eastern Kansas and western
Missouri may be able to get about a tenth of an inch or so out of
this initial round, but the setup strongly favors considerable
rainfall elsewhere. That said, though it doesn`t look particularly
concerning or impactful at this time, there`s about a 40-50% chance
of seeing some rain during this period.

The more impactful and widespread round of rain and storms looks to
arrive Thursday night and continue into much of Friday. The setup is
not too dissimilar from that of the previous evening, however, the
positioning of these features looks to be much more conducive for a
heavy rainfall event. This is especially true with the low-level jet
axis which looks to orient itself in a manner such that tropical
moisture is injected directly into eastern Kansas and
western/central Missouri. PWATs are forecast between 2" and 2.25",
comfortably exceeding the 90th percentile of climatology with mid-
/low-level RH cresting around 95% Friday morning. Preliminary
assessment of forecast soundings late Friday morning/early Friday
afternoon also depict a deep warm cloud layer which raises
confidence in efficient rainfall, though this may be limited
somewhat by a general lack of instability. Storm motion and training
potential are other factors that will need to be closely monitored
in the coming days. Currently, it appears that storms will be able
to propagate just fast enough to remain progressive...though this
might not alleviate much of the concern for heavy rainfall/flooding
given the confidence surrounding efficient warm rain processes. WPC
has retained the Slight Risk (Level 2 of 4) for excessive rainfall
that could lead to flash flooding associated with storms Thursday
night into Friday. Maximum PoPs currently sit around 60-80%, peaking
in the overnight and early morning hours.

&&


.AVIATION /06Z TAFS THROUGH 06Z THURSDAY/...
Issued at 1154 PM CDT Tue Jul 21 2026

VFR conditions are expected through the forecast with light
northeast winds and just high-level clouds moving through.
Clouds will likely become thicker late in the forecast period,
but remain above 10-15K feet.

&&

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

&&

$$

DISCUSSION...Macko
AVIATION...CDB