St. Joseph, Missouri 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

749
FXUS63 KEAX 232308
AFDEAX

Area Forecast Discussion
National Weather Service Kansas City/Pleasant Hill MO
608 PM CDT Wed Sep 23 2026

.KEY MESSAGES...

- Pleasant fall conditions continue. Highs remain around
  seasonal normals.

- Rain chances return Friday continuing through the weekend.

&&

.SHORT TERM /THROUGH THURSDAY NIGHT/...
Issued at 313 PM CDT Wed Sep 23 2026

Pleasant fall weather continues today with highs anticipated in the
mid to upper 70s for most. A building ridge gradually clears out
cloud cover resulting in relatively quiet looking skies. However,
satellite imagery combined with 500mb upper air analysis paints a
rather chaotic picture. The defining features are a pair of high
pressure systems, one over the Great Lakes, and a second along the
Gulf Coast. General troughing dominates the western CONUS. Analysis
depicts a large trough off Baja California coupled with a notable
shortwave across the northern Rockies. The interactions between
these pressure systems have been the main focus of the weather over
the past several days. The Gulf Coast high is building northward
across the central Plains bringing more stable air across the area.
This manifests as clearing clouds and increasing sunshine. RAP
analysis suggests a small low compressed in the 500mb flow between
the two highs which appears to create a small Rex block across the
Ohio River Valley. This would be a small hiccup that temporarily
slows the flow across the continent. Surface winds remain generally
from the east maintaining the flow of cooler and drier air across
the area keeping pleasant fall conditions around through Friday.

&&

.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
Issued at 313 PM CDT Wed Sep 23 2026

As we get into Friday and the weekend, the area will start to see
influence from the ongoing ridge pattern interacting with an
omega block. The omega block is formed due to a high pressure
system over the Great Lakes, along with low pressure in New
England and the Pacific Northwest. The interaction of these two
synoptic features will direct shortwaves over our region acting
as our source of lift, which will lead to a cloudy, rainy, and
gloomy weekend. The surface response to the ridging features
will cause a sharp temperature gradient over the area, with mid
80s to our south, and mid to upper 60s to our north.
Additionally, high pressure near the Gulf Coast will advect a
fetch of moisture across the Gulf, and into areas across the
Great Plains. Chances of precipitation are expected starting
Friday morning, with highest likelihood and amounts in our
northwestern counties. Progression of the shortwave eastward
will move precipitation chances across the entire area
throughout the whole day Saturday. Seasonable temperatures and
persistent cloud cover significantly reduce instability, and
limit severe weather chances. However, higher PWAT values of
1.5"-1.75" indicate that heavy downpours will be possible. Rain
and cloud cover are expected to diminish Sunday afternoon
through Sunday night as the system continues to progress.

As the shortwave moves out of the area Monday, the mid level
ridge remains over the area. There is still uncertainty about
how high temperatures may get. If the omega block holds onto
its strength, temperatures will remain seasonable, as it would
stifle warm air advection. On the other side, if the omega
block weakens, this would allow a warmer air mass to move
farther northward into our area, bringing temperatures into the
mid 80s. Ensembles have been leaning toward the omega block
breaking down and moving out of the region, making way for
another disturbance from the Pacific coast. This system would
come through the area Tuesday, bringing increased chances of
rain, and cooler temperatures.

&&

.AVIATION /00Z TAFS THROUGH 00Z FRIDAY/...
Issued at 605 PM CDT Wed Sep 23 2026

VFR conditions through the period with surface high pressure
centered over the western Great Lakes leading to winds from the
east prevailing. Will see an increase in upper level cloud cover
tomorrow ahead of the next disturbance. Considered BR near
sunrise for STJ, but with increasing high clouds, opted to leave
mention out for now.

&&

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

&&

$$

SHORT TERM...
LONG TERM...
AVIATION...BT