Flash Flood Warning 23, NWS Kansas City, MO

AREA FORECAST DISCUSSION
National Weather Service Kansas City/Pleasant Hill MO
622 PM CDT Thu Sep 21 2023

.Discussion...
Issued at 358 PM CDT THU SEP 21 2023

Key Messages:

- Scattered showers and storms will be possible tonight into
  tomorrow morning.

- Strong to severe storms as well as areas of moderate to heavy
  rainfall looking more likely for Saturday afternoon into
  Saturday night.

- Seasonal temperatures with generally dry conditions likely for
  early to mid next week.

Discussion:

The current synoptic weather pattern across the CONUS is defined
by mid level ridging over the south-central US with a closed low
over the Intermountain West with associated troughing over much of
the western CONUS. Further east over the north-central Plains
there is a shortwave trough embedded within the southwesterly
flow aloft on the far eastern periphery of the western trough.
This has generated convection over portions of NE Nebraska/NW
Iowa/SE South Dakota/SW Minnesota this afternoon. Meanwhile, a
more localized low continues to spin over northern Illinois,
keeping some cooler temperatures and cloud cover over NE Missouri.
Current conditions around the region are generally warm, with
temperatures in the low to mid 80s with scattered mid level
clouds moving in from the west. Isolated to scattered showers and
storms will be possible later this evening into the overnight
hours in association with the subtle shortwave over the Plains,
although more recent convection allowing model (CAM) guidance
suggests the better chance for showers/storms may hold off until
after 4/5 AM Friday morning, with showers and perhaps a few
thunderstorms moving west to east through the area, exiting by
early to mid afternoon. SPC has included much of the region into
a marginal risk for tonight/early Friday morning, but I am not
terribly enthused by the severe threat. Given precipitation
chances and cloud cover, high temperatures for tomorrow should be
a bit cooler (mid 70s to near 80 degrees).

Shower and thunderstorm chances return by tomorrow night into
early Saturday morning as an eastern lobe of the western trough
pivots into South Dakota into SE Nebraska. The closed mid level
low over the Intermountain West finally moves into central South
Dakota by Saturday afternoon with the accompanying surface cold
front moving west to east across eastern Kansas. Thunderstorms
should initiate along the front by early to mid afternoon over
WFO Topeka's area, with these likely growing upscale into a line
or broken line of storms by the time they enter our area in far
eastern Kansas by mid to late afternoon. Storms should continue to
move east to west through the area through the remainder of
Saturday evening into early Sunday morning. There will be decent
pairing of instability and deep layer shear, so strong to severe
thunderstorms will be possible. As of now, SPC has maintained a
slight risk over the region. Given the fact that storms will
likely be of a linear storm mode, strong thunderstorm wind gusts
should be the primary threat, but large hail will also be possible
and a tornado or two cannot be ruled out, especially if low level
wind shear is favorable for mesovortices. In addition to the
strong to severe storms, moderate to heavy rainfall will also be
possible, with the current WPC forecast showing widespread 1.5" to
2" of rain with locally higher amounts possible. There is still
some uncertainty in the exact timing and evolution of the trough
ejection and frontal passage, so finer details of the forecast
should be ironed out in the next 24 to 36 hours or so.

A few showers and storms may linger into Sunday afternoon,
especially if the cold front is slow to finally clear east of the
area. Highs on Sunday should be several degrees cooler behind the
front (low 70s over NE MO to mid to upper 70s elsewhere). As we
head into next week, ridging looks to build in over the west
central CONUS. There will be a few periods of low chance PoPs, but
all in all dry conditions are favored with near seasonal
temperatures with afternoon highs in the 70s and lows in the 50s.

&&

.Aviation...(For the 00Z TAFS through 00Z Friday Evening)
Issued at 621 PM CDT THU SEP 21 2023

With current T-storm activity being close to terminals, entered a
two to three hour VC group through tonight when diurnal cycle
becomes less favorable for storm maintenance. Another round of
T-storms expected later tonight. Still not certain about timing
and/or coverage, but felt aggressive enough to put in -TSRA with
some VIS restriction. That activity should move out pretty
quickly, leaving dry forecast with low clouds through the morning.

&&

.EAX WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
MO...NONE.
&&

Discussion...BMW
Aviation...Leighton

Hazardous Weather Outlook
National Weather Service Kansas City/Pleasant Hill MO
1208 PM CDT Thu Sep 21 2023

KSZ025-057-060-102>105-MOZ001>008-011>017-020>025-028>033-037>040-
043>046-053-054-221715-
Atchison KS-Miami-Linn KS-Doniphan-Leavenworth-Wyandotte-Johnson KS-
Atchison MO-Nodaway-Worth-Gentry-Harrison-Mercer-Putnam-Schuyler-
Holt-Andrew-De Kalb-Daviess-Grundy-Sullivan-Adair-Buchanan-Clinton-
Caldwell-Livingston-Linn MO-Macon-Platte-Clay-Ray-Carroll-Chariton-
Randolph-Jackson-Lafayette-Saline-Howard-Cass-Johnson MO-Pettis-
Cooper-Bates-Henry-
1208 PM CDT Thu Sep 21 2023

This hazardous weather outlook is for northwest...north central and
west central Missouri...as well as extreme eastern Kansas.

.DAY ONE...This Afternoon and Tonight

 There will be a chance for thunderstorms later tonight, into early
Friday morning. Severe weather is unlikely, but a few storms could be
strong, with gusty winds and small hail probable.

.DAYS TWO THROUGH SEVEN...Friday through Wednesday

 There is a marginal risk of a few severe thunderstorms in far
 northwestern Missouri Friday night. Hail to the size of quarters
and wind gusts to 60 mph will be the primary hazard concerns.

 There is a slight risk of severe thunderstorms across the region
 Saturday evening and night. A line of storms is expected to move
 into the Kansas - Missouri border region 6 to 9 PM. Any strong
 storms could result in half dollar size hail and wind gusts to 60
 mph.

 There is a slight risk of excessive rainfall Saturday night.
 Locally heavy rainfall may result in an increased flooding risk.

 More detailed information can be accessed at...
 https://www.weather.gov/eax/hwo

Special Weather Statement
National Weather Service Kansas City/Pleasant Hill MO
707 PM CDT Thu Sep 21 2023

KSZ057-MOZ043-053-220030-
Miami KS-Bates MO-Cass MO-
707 PM CDT Thu Sep 21 2023

...A strong thunderstorm will impact portions of southeastern Miami,
southwestern Cass and northwestern Bates Counties through 730 PM
CDT...

At 707 PM CDT, Doppler radar was tracking a strong thunderstorm near
Drexel, or 10 miles east of La Cygne, moving east at 15 mph.

HAZARD...Wind gusts up to 50 mph and penny size hail.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects. Minor damage to outdoor objects is
         possible.

Locations impacted include...
Adrian, Archie, Drexel, Amsterdam, Merwin and Passaic.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

&&

LAT...LON 3830 9461 3839 9461 3839 9466 3844 9469
      3858 9441 3833 9428
TIME...MOT...LOC 0007Z 249DEG 13KT 3840 9457

MAX HAIL SIZE...0.75 IN
MAX WIND GUST...50 MPH

CDB

Special Weather Statement
National Weather Service Kansas City/Pleasant Hill MO
803 PM CDT Thu Sep 21 2023

MOZ043-220130-
Cass MO-
803 PM CDT Thu Sep 21 2023

...A strong thunderstorm will impact portions of southwestern Cass
County through 830 PM CDT...

At 803 PM CDT, Doppler radar was tracking a strong thunderstorm over
Freeman, or 9 miles southwest of Harrisonville, moving northeast at
10 mph.

HAZARD...Winds in excess of 40 mph and penny size hail.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects. Minor damage to outdoor objects is
         possible.

Locations impacted include...
Freeman and Lake Annette.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

Torrential rainfall is also occurring with this storm and may lead to
localized flooding. Do not drive your vehicle through flooded
roadways.

Frequent cloud to ground lightning is occurring with this storm.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.

&&

LAT...LON 3850 9447 3857 9459 3871 9452 3859 9433
TIME...MOT...LOC 0103Z 214DEG 8KT 3858 9450

MAX HAIL SIZE...0.75 IN
MAX WIND GUST...40 MPH

CDB