Special Weather Statement, NWS Kansas City, MO

AREA FORECAST DISCUSSION
National Weather Service Kansas City/Pleasant Hill MO
633 AM CDT Thu Aug 12 2021

.Discussion...
Issued at 349 AM CDT THU AUG 12 2021

Message of the Day

- An Excessive Heat Warning remains in effect until this evening
  for the KC Metro for multiple days of heat indices around
  105-110 degrees and low temperatures this morning around 80
  degrees. The Heat Advisory remains in effect until this evening
  for the rest of the forecast area for heat indices between
  100-107 degrees and low temperatures this morning in the mid to
  upper 70s.

- There is a slight chance for an additional isolated or two to
  develop along the MO/IA border for the next few hours. Any storm
  that may develop should behave, but can't rule a strong wind
  gusts.

- Strong to severe storms are expected late this afternoon into
  the overnight hours for the majority of the area. Winds up to
  60 mph is the main concern, but hail up to quarter-sized and
  heavy downpours leading to localized flash flooding are possible
  as well.

Discussion

Some convection developed early this morning just north of the
MO/IA border. The LLJ is nosing into this area where there is also
a surface frontal boundary stretched from west to east. Support
aloft is lacking, so coverage has been isolated and those storms
have already dissipated. An isolated storm or two is possible for
the next few hours along the MO/IA border, but chances continue to
decrease as we approach sunrise, which is when the LLJ will
weaken substantially.

As we move through the day, the frontal boundary will retreat north
as a warm front. This keeps us in the warm sector with temperatures
and heat indices remaining at dangerous levels. Temperatures this
morning are in the upper 70s to low 80s and are only expected to
drop another few degrees by sunrise. Overall this afternoon, it
will be a hair cooler today than yesterday, but still dangerous,
especially since this is day four of the heat and humidity. Those
north of HWY 36 will see temperatures in the low to mid 90s with
heat indices between 100-105. South of HWY 36, we will see mid
90s with heat indices between 105-110. The highest temperatures
and heat indices will be in the KC Metro, so the Excessive Heat
Warning remains in effect there until this evening. The Heat
Advisory also remains in effect for the rest of the forecast area
until this evening. The boundary will finally move through the
area tonight as a cold front, bringing us relief for Friday and
the weekend. High temperatures are forecast to be in the 80s, with
low temperatures in the 60s.

The cold front is expected to enter our area around 1 PM this
afternoon and will be the focus for thunderstorm development today.
There is a chance for isolated convection to develop between 1 and 4
PM over areas from St. Joseph to Kirksville, but best chances for
storm development will come closer to 5-7 PM, when there won't be
much of a cap and the LLJ starts to strengthen. Storms will become
widely scattered overnight as a shortwave trough moves through
the region. Once again, we won't be lacking in instability with
4000-5000 J/kg of CAPE in the region. The deep layer shear looks
limited, but still 25 kts is enough to support some strong to
severe storms. Better chances for hail will be when storms first
develop, but the main concern will quickly transition to strong to
severe wind gusts. PWATs are also very high (~2 inches), so
moderate to heavy rainfall leading to some localized flash
flooding concerns is possible as well. The best chance for strong
to severe storms will be late this afternoon through the early
overnight hours. Localized flash flooding concerns will grow the
more rain areas get. The cold front and storms will generally move
south overnight with those in our southern counties more likely
seeing storms late Thursday/early Friday. Storms will continue
into the daylight hours, mainly for those south of the Missouri
River.

Storms will gradually exit the area throughout the day Friday with
the front. However, some small storm chances will linger through the
weekend because it looks like the front won't get too far,
stalling out to our south-southwest near the OK/AR border. Still,
it looks like the drier air advecting in from the east will limit
rain chances.

No major pattern change is anticipated right now for the beginning
of next week, so temps in the 80s with dry conditions are forecast.

&&

.Aviation...(For the 12Z TAFS through 12Z Friday Morning)
Issued at 633 AM CDT THU AUG 12 2021

Some isolated convection is developing this morning on the nose of
the LLJ. This activity should decrease as the sun comes up and the
LLJ weakens. The rest of the morning and much of the afternoon
should be quiet. Winds will become a little breezy again this
afternoon. A cold front will enter the area this afternoon and
work its way through the area tonight. Convection is expected to
develop along the front. Could be as early as 18Z, but most likely
will occur closer to 00Z. Convection will be more isolated
initially, eventually becoming scattered. Storm chances will
continue into the overnight hours. Difficult to say how TAF sites
will be impacted during the overnight period with high res models
varying more this far out, but storm chances do exist. Storms
will move south with the front, both of which will move out of
the area Friday morning.

&&

.EAX WATCHES/WARNINGS/ADVISORIES...
KS...Heat Advisory until 8 PM CDT this evening for KSZ025-057-060-102.

     Excessive Heat Warning until 8 PM CDT this evening for
     KSZ103>105.

MO...Heat Advisory until 8 PM CDT this evening for MOZ001>008-011>017-
     020>025-030>033-038>040-043>046-053-054.

     Excessive Heat Warning until 8 PM CDT this evening for MOZ028-
     029-037.

&&

Discussion...Atkins
Aviation...Atkins

Hazardous Weather Outlook
National Weather Service Kansas City/Pleasant Hill MO
519 AM CDT Thu Aug 12 2021

KSZ025-057-060-102>105-MOZ001>008-011>017-020>025-028>033-037>040-
043>046-053-054-131030-
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-
519 AM CDT Thu Aug 12 2021

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

.DAY ONE...Today and Tonight

 A few showers and storms are possible early this morning. The
 Excessive Heat Warning for area surrounding the KC Metro and the
 Heat Advisory for everywhere else is in effect until 8pm tonight
 due to morning temps in the upper 70s, lower 80s and ongoing heat
 with indices around 105-110 degree F. Another chance for storms is
 tonight after 4-5pm. Strong, damaging wind and frequent lightning
 are the main concern with these developing storms.

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

.DAYS TWO THROUGH SEVEN...Friday through Wednesday

 A cool-down is expected by Friday with max temps in the 80s and heat
 indices following closely behind.

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

Special Weather Statement
National Weather Service Kansas City/Pleasant Hill MO
429 AM CDT Thu Aug 12 2021

MOZ005-121000-
Harrison MO-
429 AM CDT Thu Aug 12 2021

...A strong thunderstorm will impact portions of northeastern
Harrison County through 500 AM CDT...

At 429 AM CDT, Doppler radar was tracking a strong thunderstorm near
Lamoni, or 16 miles southeast of Mount Ayr, moving east at 20 mph.

HAZARD...Winds in excess of 30 mph and nickel 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.

This storm will remain over mainly rural areas of northeastern
Harrison County.

This includes Interstate 35 in Missouri between mile markers 110 and
114.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

&&

LAT...LON 4049 9377 4053 9409 4057 9409 4058 9377
TIME...MOT...LOC 0929Z 271DEG 19KT 4057 9398

MAX HAIL SIZE...0.88 IN
MAX WIND GUST...30 MPH

Grana

Special Weather Statement
National Weather Service Kansas City/Pleasant Hill MO
458 AM CDT Thu Aug 12 2021

MOZ005-006-121045-
Mercer MO-Harrison MO-
458 AM CDT Thu Aug 12 2021

...A strong thunderstorm will impact portions of northern Mercer and
northeastern Harrison Counties through 545 AM CDT...

At 457 AM CDT, Doppler radar was tracking a strong thunderstorm 7
miles southeast of Lamoni, or 11 miles south of Leon, moving east at
20 mph.

HAZARD...Winds in excess of 30 mph and nickel 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...
Princeton, Mercer, Cainsville, Blythedale, Pleasanton and South
Lineville.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

&&

LAT...LON 4038 9337 4043 9397 4058 9393 4058 9337
TIME...MOT...LOC 0957Z 271DEG 19KT 4058 9381

MAX HAIL SIZE...0.88 IN
MAX WIND GUST...30 MPH

Grana

Special Weather Statement
National Weather Service Kansas City/Pleasant Hill MO
600 AM CDT Thu Aug 12 2021

MOZ006-121130-
Mercer MO-
600 AM CDT Thu Aug 12 2021

...A strong thunderstorm will impact portions of central Mercer
County through 630 AM CDT...

At 600 AM CDT, Doppler radar was tracking a strong thunderstorm near
Mercer, or 19 miles south of Leon, moving east at 20 mph.

HAZARD...Winds in excess of 30 mph and nickel 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...
Princeton and Mercer.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

&&

LAT...LON 4034 9337 4039 9369 4056 9369 4058 9345
      4058 9337
TIME...MOT...LOC 1100Z 271DEG 17KT 4047 9362

MAX HAIL SIZE...0.88 IN
MAX WIND GUST...30 MPH

Grana

Special Weather Statement
National Weather Service Kansas City/Pleasant Hill MO
837 AM CDT Thu Aug 12 2021

MOZ008-121345-
Schuyler MO-
837 AM CDT Thu Aug 12 2021

...A strong thunderstorm will impact portions of southeastern
Schuyler County through 845 AM CDT...

At 837 AM CDT, Doppler radar was tracking a strong thunderstorm near
Downing, or 10 miles west of Memphis, moving east at 25 mph.

HAZARD...Winds in excess of 30 mph and nickel 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...
Downing.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

&&

LAT...LON 4035 9243 4048 9247 4051 9235 4035 9235
TIME...MOT...LOC 1337Z 258DEG 21KT 4041 9235

MAX HAIL SIZE...0.88 IN
MAX WIND GUST...30 MPH

PP

Special Weather Statement
National Weather Service Kansas City/Pleasant Hill MO
838 AM CDT Thu Aug 12 2021

MOZ008-121415-
Schuyler MO-
838 AM CDT Thu Aug 12 2021

...A strong thunderstorm will impact portions of southeastern
Schuyler County through 915 AM CDT...

At 837 AM CDT, Doppler radar was tracking a strong thunderstorm near
Downing, or 11 miles west of Memphis, moving east at 20 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...
Downing.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

&&

LAT...LON 4035 9240 4034 9245 4047 9248 4049 9235
      4035 9235
TIME...MOT...LOC 1337Z 265DEG 17KT 4041 9237

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

BMW