MD 1564 CONCERNING TORNADO WATCH 450… FOR WESTERN NEBRASKA…NORTHEAST COLORADO…AND NORTHWEST KANSAS
Mesoscale Discussion 1564
NWS Storm Prediction Center Norman OK
0927 PM CDT Thu Aug 19 2021
Areas affected...Western Nebraska...Northeast Colorado...and
Northwest Kansas
Concerning...Tornado Watch 450...
Valid 200227Z - 200400Z
The severe weather threat for Tornado Watch 450 continues.
SUMMARY...Upscale growth of ongoing convective activity will support
the potential for damaging winds, severe hail, and perhaps a tornado
or two across WW 450.
DISCUSSION...Storms that have developed across the region are now
beginning to merge into a multicell cluster, with the strongest
cells located in far northeast Colorado and southwest Nebraska. The
environment, characterized by MLCAPE of 1500-2000 J/kg and 40-50 kt
of effective bulk shear, continues to support supercell/embedded
supercell structures, with persistent mid-level rotation and brief
low-level rotation noted. As such, storms have mainly produced large
hail, including a report of 2 inch hail in Chase county, Nebraska.
The trend toward upscale growth is expected to continue for the next
few hours as the low-level jet continues to strengthen. The primary
severe threat may transition to damaging winds, as evidenced by a 71
mph gust measured at Imperial, Nebraska, at 0219 UTC. Large hail
will remain possible with the most intense embedded cells,
particularly along the southern flank of the convective line where
renewed convective development is occurring and will remain
possible. A tornado or two also remains possible given a notable
increase in low-level shear to near 35-40 kt and enlarged hodographs
evident in regional VAD wind profiles.
..Karstens.. 08/20/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...GID...LBF...GLD...BOU...
LAT...LON 39120094 39120206 40030266 40120267 40640251 41210173
42140117 42300017 41669929 39979945 39290025 39120072
39120076 39120078 39120094
