St. Joseph, Missouri 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

148
FXUS63 KEAX 190538
AFDEAX

Area Forecast Discussion
National Weather Service Kansas City/Pleasant Hill MO
1238 AM CDT Tue May 19 2026

...06 Aviation Update...

.KEY MESSAGES...

* Significant threat for severe weather across NW Missouri this
  evening with destructive hail, damaging winds and tornadoes.
  This threat will transition to a damaging winds and QLCS
  tornadoes as scattered storms develop into a line and build
  southeast.

* Substantial flood threat tonight across the region with
  rainfall rates expected to exceed 2"/hr. Flood watch in effect
  tonight into Tuesday morning. Additional rainfall amounts of
  1.5-3+" with pockets exceeding 5".

* Cooler and drier conditions develop on Tuesday and continue into
  Wednesday.

* Rainfall chances return to the region Thursday through the end
  of the weeekend.

&&

.DISCUSSION...
Issued at 253 PM CDT Mon May 18 2026

Mature trailing stratiform MCS worked through the area overnight
leading to a widespread 1-2 inches of rain across the region.  Saw
MCS backbuild across central Missouri through the late morning,
keeping temperatures quite cool through mid-day. Have seen signs of
gravity waves emanating from the tail end of the the MCS, spreading
to the north-northwest.

Have started to see some partial-rapid clearing across eastern KS
into western Missouri leading to nice warming- roughly west of I-35.
Pseudo warm front/outflow boundary is poised just south of the
forecast area across central Missouri. This boundary may try to lift
north through the late afternoon hours.  If that occurs, could see
an isolated storms develop south of a line from Butler through
Clinton leading to large hail/gusty winds. Expect surface
temperatures to continue to warm through the afternoon hours into
the upper 70s to 80s, leading to rapidly increasing instability.  By
late this afternoon, expect moderate to extreme instability with SB
CAPE values of 4000-5000 J/kg roughly along and west of the I-35
corridor.

Surface low pressure centered near Salina KS is expected to lift
northeast this afternoon to southwest Iowa into the evening.
Discreet supercells have already begun developing across central
into northern KS, building east in time in what is a very volatile
environment.  0-6 km shear is in the 40-50 knot range across eastern
KS should easily support supercells, with the potential for very
large hail and tornadoes.  Expect supercells to remain discreet
building into Northwest Missouri in the early evening hours, capable
of producing very large hail, damaging winds and the potential for
strong tornadoes.  As the severe weather event evolves, expect the
supercells to evolve into a squalline and build southeast in time.
Expect severe threat to transition towards damaging winds, but could
still see QLCS tornadoes with embedded supercells along the line.

Training storms, along with precipitable water values of nearly two
inches and deep warm cloud depths will lead to efficient rainfall.
CAMs have been fairly consistent with another 1.5-3+" of rainfall
across the region tonight, with pockets of 5+". HREF and REFs
probabilities for 2"/hr rainfall rates are approaching 50%. Flash
flood guidance across the area is low with the recent rains,
generally running from 1-2.5"/6 hour period. Collaborated with WPC
and surrounding offices to raise excessive rainfall outlook to
moderate across most of the area. Cams suggest storms may linger
Tuesday morning as the surface boundary moves slowly through the
area.  Have extended the flood watch through 18Z south of the
Missouri River.

Much cooler conditions are expected midweek behind the front with
high in the 60s and lows in the 40s.  A developing trough late week
across the Northern Plains could bring additional instability
showers and storms to the region as early as Thursday.

&&

.AVIATION /06Z TAFS THROUGH 06Z WEDNESDAY/...
Issued at 1237 AM CDT Tue May 19 2026

Showers and thunderstorms will continue to shift east and away
from the TAF sites through the night. Stratiform rain along with
isolated thunderstorm activity will continue overnight behind
this line of severe thunderstorms before coming to an end. CIGS
are expected to lower to IFR and MVFR overnight as rain tapers
off, and then gradually rise through the morning and afternoon
on Tuesday, becoming VFR in the afternoon. Winds will be
shifting tonight to west and northwest, then out of the north
during the day on Tuesday.

&&

.EAX WATCHES/WARNINGS/ADVISORIES...
MO...Flood Watch through this afternoon for MOZ020>022-028>033-
     037>040-043>046-053-054.
     Flood Watch until 7 AM CDT this morning for MOZ001>007-011>016-
     023-024.
KS...Flood Watch through this afternoon for KSZ025-057-060-102>105.

&&

$$

DISCUSSION...BT
AVIATION...WFO EAX