St. Joseph, Missouri 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

325
FXUS63 KEAX 282330
AFDEAX

Area Forecast Discussion
National Weather Service Kansas City/Pleasant Hill MO
630 PM CDT Mon Sep 28 2026

.KEY MESSAGES...

- Warmer and dry conditions expected through Tuesday for most.

- Several rounds of showers and storms are expected (>95% chance
  for accumulating rainfall) across the forecast area Tuesday
  night through Thursday night. Heavy rainfall and flooding
  will be possible.

&&

.DISCUSSION...
Issued at 221 PM CDT Mon Sep 28 2026

A quiet day has prevailed across the area thanks to the influences
of building mid-level ridging and lingering surface high pressure.
With the 850mb thermal ridge remaining displaced just to the west,
temperatures should largely  be similar / within a couple degrees of
yesterday in most cases. The greatest exception likely being NE
areas of the CWA and state where temps today will be more on the
order of 10 degrees warmer, but pleasant in the lwo-mid 70s, as
sunshine prevails in place of the fully overcast day Sunday.

The quiet / dry conditions will be pretty short lived though as the
well advertised shift to wet conditions takes place through the rest
of the week. The large scale synoptic pattern remains well
corroborated among the deterministic globals and their ensembles.
This being nor`easter remnants being ushered eastward, western CONUS
trough/cut-off low digging into SW US, and remnants of Hurricane
Polo beginning to lift northward across Baja California early this
week. With the building and eastward shifting mid-level ridging over
the central CONUS, deep Gulf moisture too will begin to stream
northward. All of which will prime the wider region for widespread
showers and storms and the potential for both river and areal
flooding. This is further reflected via deterministic PWats of >2.00
inches, which would be near or at record levels for this time of the
year, based on TOP sounding climatology and at 99th percentile or
MAX within GEFS/Euro Ensemble SA Tables by later Tuesday onward. On
the rainfall efficiency front, the deep influx of moisture
unsurprisingly aids in pushing warm cloud layer depths towards 4km,
hinting at potential for efficient rainfall via tropical/warm cloud
processes. Some limitation on rainfall rates though with likely
weaker instability due to the abundantly ongoing moist profiles,
which may shift the flooding potential away from typical warm season
flash flooding and toward slower onset areal and river flooding.
Anyways...

Initial precipitation chances move into the NW CWA later Tuesday as
a surface to low level boundary drifts southward out of the Northern
Plains. Nocturnal LLJ enhances chances through the over night, and
the boundary is expected to hang up over the Nebraska/Iowa areas
through Wednesday as cyclogenesis over the Southern High Plains
increases low level flow. This places the greatest initial heavy
rain and flood potential toward far NE Kansas and NW Missouri and up
through large portions of eastern Nebraska and western to central
Iowa through Wednesday. The NW CWA may just miss out on the heaviest
rainfall axis, and this uncertainty is reflected in 48hr NBM
25th/75th ranges of around 1.2 to 3.5 inches through Wednesday
night. And keep in mind, NBM will not capture the
potential/likely embedded higher amounts. Given the potential,
have coordinated an initial Flood Watch for said areas with
northern neighbors, beginning Tuesday night and through Thursday
night.

As the synoptic pattern evolves through mid-week, western
trough/Polo remnants lifting into the Plains, heavy rain location
begins to shift as well; along and ahead of the developing surface
cold front and further north along the deformation axis by Wednesday
night and Thursday. This transition is interesting in that it "may"
result in portions of the area, including the Kansas Cit Metro,
being gaped or surrounded by the heavier rainfall amounts. Of
course, this too remains a couple/few days out and subtle shifts in
tracks too will shift the heavy rain axis locations. Regardless, it
will rain area wide. Just the nuance of where the heavy rain risks
shift to after Wednesday. The 24hr NBM 25th/75th ranges are
unsurprisingly wide (in amount and over a very wide area), from
around 0.70 to 3.00 inches. Same NBM caveat as above. Generally
anticipate some expansion to the Flood Watch location over the
next couple forecast cycles as details continue to come into
increasing focus. Best odds may be over northern areas, where
deformation area may linger and soil moistures are most
saturated over the area.

Area looks to dry out later Friday and into the weekend, but both
deterministic and ensemble guidance hint at some low-end
opportunities for precipitation to linger over central Missouri
before more substantial drying (cold front) drops in from the north
Sunday.

&&

.AVIATION /00Z TAFS THROUGH 00Z WEDNESDAY/...
Issued at 625 PM CDT Mon Sep 28 2026

VFR conditions are expected through the period, with increasing
upper level clouds moving in from the west by Tuesday
afternoon. Light southeasterly winds tonight should become more
southerly by Tuesday morning, with sustained winds up to around
10 knots on Tuesday afternoon.


&&

.EAX WATCHES/WARNINGS/ADVISORIES...
MO...Flood Watch from late Tuesday night through late Thursday
     night for MOZ001>005-011-012.
KS...Flood Watch from late Tuesday night through late Thursday
     night for KSZ102.

&&

$$

DISCUSSION...Curtis
AVIATION...BMW