St. Joseph, Missouri 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

675
FXUS63 KEAX 151936
AFDEAX

Area Forecast Discussion
National Weather Service Kansas City/Pleasant Hill MO
236 PM CDT Tue Sep 15 2026

.KEY MESSAGES...

- Multiple rounds of rainfall anticipated across NE KS and NW MO
  through tomorrow morning. Heavy downpours are expected which
  may lead to flash flooding as well as river flooding. A Flood
  Watch is in effect for NW MO and NE KS (including the KC
  metro) from 1PM Tuesday through 1PM Wednesday.

- Wide range of temperatures anticipated NW MO and NE KS around
  80 and central MO in the mid 90s. There is the potential for
  some hazardous heat across central and southern MO and
  tomorrow and Thursday as heat index values approach
  100F-105F.

- Additional rounds of storms area expected this weekend which
  may lead to additional flooding.

&&

.DISCUSSION...
Issued at 231 PM CDT Tue Sep 15 2026

The main concern in the short term is the potential for heavy
rainfall late this afternoon through tomorrow morning potentially
leading to flash and river flooding. In addition there will be the
chance for a few strong storms late this afternoon through this
evening that will be capable of damaging winds and large hail. The
focus for these storms and the heavy rainfall will be a slow moving
cold frontal boundary. This boundary is slowly sagging into the
area, and is currently extending from Unionville to St Joseph early
this afternoon. This front is expected to continue to slowly sink
south through the afternoon. Light showers and cloud cover had
persisted north of this boundary creating an area of differential
heating where temperatures have achieved the low to mid 90s ahead of
the boundary and 70s north. The environment ahead of the front is
moderately unstable with MUCAPE values in the 2000-3000J/Kg range
however, the stronger effective shear lags behind the boundary. As
such, the main threat with strongest storms that develop late this
afternoon into the evening will be capable of localized damaging
winds and brief small hail. What is the biggest concern however, is
the threat for heavy rainfall that trains along and north of the
boundary this evening through the overnight. PWATs are near record
values Betteann 2.20"-2.40" so storms will be extremely efficient
with rainfall totals of 2-4" forecast for portions of northeastern
Kansas and NW Missouri. This will lead to a flood threat
particularly for areas of NE KS/NW MO that received 4-7" of rain
yesterday morning. As such a flood watch is in effect for these
areas through early tomorrow afternoon.

Storms are expected to continue through the overnight tonight fueled
by a southwesterly 30-35kt LLJ nosing into the area. The LLJ is
progged to weaken tomorrow morning allowing showers to dissipate.
Tomorrow afternoon into tomorrow morning the frontal boundary will
lift back north across the CWA as a warm front. Showers and
thunderstorms are expected with this feature as it lifts north with
the best chances for storms (25-35%) along and north of Highway 36
corridor. Highs tomorrow will range from the low to mid 90s south of
the Missouri River, where the warm front will pass earlier in the
day, to the mid 70s across northern Missouri where the warm front
won`t lift through until tomorrow night. Thursday into Thursday
night looks to remain mostly dry and warm with the war front north
of the area. Highs will range from the mid 80s to mid 90s. Heat
index values south of the Missouri River may approach 105 degrees
with a heat advisory possibly being necessary.

The upper-level ridge will shift slightly back toward the south-
central US, drying things out briefly Friday morning and lifting
high temperatures into the 90s. However, this will be short-lived,
as an upper-level trough and surface cold front move into our region
Friday night into Saturday, bringing rain along the front. PWAT
values from the GFS range from 1.5-2.0 inches for Saturday and
Sunday, which fall in the 90th percentile for climatology. This, on
top of the rain we could see earlier in the week, may increase the
risk of flooding, especially in NW MO. By Monday, the cold front
moves out and high pressure moves in bringing cooler and drier
weather with highs in the 70s.

&&

.AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/...
Issued at 1224 PM CDT Tue Sep 15 2026

VFR conds will prevail thru 23Z-00Z when mod tsra will move into
the into the terminals. Storms are expected to cont at the TAF
sites thru 13Z-15Z with reduced vis to 3-5SM. Cigs will remain
VFR thru 00Z when bkn cigs around 4kft are fcst (except STJ
which will become MVFR aft 23Z). We will then see a gradual
lowering of cigs thru the evening with cigs dropping into MVFR
around 03Z-05Z and into IFR btn 06Z-08Z. Winds to begin the TAF
pd will be out of the W around 10kts (except STJ which will
begin he TAF northerly) becmg northerly around 10kts aft 00Z.
By 03Z-05Z winds will shift to the east while remaining around
10kts.

&&

.EAX WATCHES/WARNINGS/ADVISORIES...
MO...Flood Watch through Wednesday afternoon for MOZ001>006-011>015-
     020>022-028-029-037.
KS...Flood Watch through Wednesday afternoon for KSZ025-102>105.

&&

$$

DISCUSSION...73/IPC
AVIATION...73