SPC Mesoscale Discussion

SPC MD 1181

MD 1181 CONCERNING SEVERE THUNDERSTORM WATCH 354... FOR CENTRAL AND EASTERN NEBRASKA...NORTHERN KANSAS...SOUTHWEST IOWA...FAR NORTHWEST MISSOURI

Mesoscale Discussion 1181
NWS Storm Prediction Center Norman OK
0123 AM CDT Sat Jul 11 2020

Areas affected...Central and Eastern Nebraska...Northern
Kansas...Southwest Iowa...Far Northwest Missouri

Concerning...Severe Thunderstorm Watch 354...

Valid 110623Z - 110830Z

The severe weather threat for Severe Thunderstorm Watch 354
continues.

SUMMARY...A wind damage and isolated large hail threat will likely
continue across central and eastern Nebraska over the next few
hours. The severe threat may eventually impact far northern Kansas
and southwest Iowa. Concerning WW 354, a watch extension in time may
be necessary for Custer County, Nebraska.

DISCUSSION...The latest mosaic radar imagery shows an MCS over
eastern Nebraska, with a broken line of thunderstorms moving through
southeast Nebraska. These storms are located just ahead of a subtle
shortwave trough evident on water vapor imagery in a moderately
unstable airmass. In addition to the instability, a plume of steep
mid-level lapse rates extends from the central High Plains eastward
across much of Nebraska and northern Kansas. This combined with
moderate deep-layer shear, evident on the WSR-88D VWP at Hastings,
will support a wind damage and hail threat as the convective line
moves southward across southeast Nebraska over the next few hours.
There is a cold pool behind the convection and there have been a few
severe wind gusts. However, the overall severe threat should become
more isolated with time, based on weaker downstream instability,
warming cloud-top temperatures and a slow weakening of the leading
edge of the convection.

Further to the northwest, and east-to-west band of thunderstorms are
also ongoing in north-central Nebraska. These storms are located to
the southeast of a instability maximum of 2000 to 2500 J/kg,
according to the RAP. A 30 to 40 kt low-level jet in the central
High Plains was feeding the convection from the south-southwest. In
addition, the WSR-88D VWP in north-central Nebraska had 60 kt of 0-6
km shear. This environment will support supercell development and
isolated large hail will be possible. A wind damage threat will also
exist. The severe threat should move southward across central
Nebraska over the next few hours.

..Broyles.. 07/11/2020

...Please see www.spc.noaa.gov for graphic product...

ATTN...WFO...DMX...EAX...OAX...TOP...GID...LBF...GLD...

LAT...LON   42080018 42090069 41910095 41340098 40980084 40730063
            40079991 39779934 39619902 39509811 39499721 39619604
            39969526 40499500 40889495 41459511 41649537 41929584
            42129649 41929695 41629718 41409740 41169801 41089854
            41209903 41849972 42080018