St. Joseph, Missouri 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

744
FXUS63 KEAX 121101
AFDEAX

Area Forecast Discussion
National Weather Service Kansas City/Pleasant Hill MO
601 AM CDT Tue May 12 2026

.KEY MESSAGES...

- Chance (15-25%) for storms Tuesday. Some of these may be strong to
  severe Tuesday afternoon-evening.

- Warming temperatures through the rest of the week with 90 degree
  highs possible Friday - Sunday.

- Unsettled weather this weekend into next week with multiple
  chances for showers and storms.

&&

.DISCUSSION...
Issued at 220 AM CDT Tue May 12 2026

A strong shortwave trough, currently moving through North Dakota and
into Minnesota, will dive southeastward through the western
Great Lakes later today. This wave will push a cold front
southward into/through the forecast area this afternoon and this
evening. Southerly to southwesterly surface and low-level flow
ahead of the front will advect moisture northward such that by
this afternoon we may see dewpoints climb into the mid to upper
50 degree range. This will help lead to modest instability with
mean MUCAPE values ranging from 1000 to 1500 J/kg in our western
zones with lower values further northeast, removed from the
slightly better lower-level moisture availability. Strong mid
and upper-level winds, associated with the shortwave trough,
will help lead to fairly strong deep-layer shear, with with
40-50kts of 0-6km shear available. If we had better moisture
available, this would be a potentially volatile northwest flow
supercell setup. But as it is, there`s some uncertainty over
whether we can get storms to even develop. With strongly veered
surface winds, convergence along the front is limited,
particularly during peak heating. This decreases confidence that
anything will even initiate. Given all this, have limited PoPs
to just slight/isolated mention along the southward advancing
front this afternoon and evening. Forecast soundings show steep
low-level lapse rates with inverted-V like appearance. This
suggest potential for some strong downdrafts in the strongest
storms. Steep mid-level lapse rates may also lead to severe hail
in the strongest storms as well. This is all conditional on if
storms can develop in this fairly marginal setup.

Temperatures cool slightly for Wednesday as a cooler and drier
airmass moves into the region. But for the later half of the
week, a warming trend continues to look likely with highs
climbing into the upper 80s to possibly lower 90s for Friday and
through the weekend. There is a fair amount of uncertainty with
these temperatures as it also looks unsettled with multiple
chances for precipitation that could inhibit temperatures from
reaching their potential. The region should see persistent
southerly flow with moisture streaming northward from a wide-
open Gulf. The moisture will help lead to better/ stronger
instability Friday-Sunday. At the same time, the region will be
in between the polar jet to the north and the subtropical jet
to our south, leading to fairly weak mid/upper level flow and
limiting available shear. This essentially looks like a summer-
time pattern with potential for afternoon storms and possibly an
MCS rolling through. From a probabilistic perspective, for the
72 hours ending 12Z Monday, there is generally a 25-40% chance
for at least an inch of rain. There is also roughly a 10-15%
chance for at least 2". These aren`t high probabilities by any
means, but it points to the potential at least, for a wet
weekend. It isn`t until late in the forecast/early next work
week, that a stronger upper-level system moves through and
pushes a cooler and drier airmass into the area that the
precipitation chances diminish.

&&

.AVIATION /12Z TAFS THROUGH 12Z WEDNESDAY/...
Issued at 601 AM CDT Tue May 12 2026

VFR conditions expected through the forecast. Southwesterly
winds will increase several hours after sunrise with between 25
and 30kts. A cold front will move through the area this
afternoon and evening, with a small chance for showers and
storms for mainly the KC terminals and southward. Chances
continue to look small enough to keep any mention out of the
forecast. Rather, continued mention of a mid-level cloud deck
moving through associated with the front. Winds become
northwesterly this evening behind the front with winds generally
10kts and less from 00Z onward through the overnight.

&&

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

&&

$$

DISCUSSION...CDB
AVIATION...CDB