ZCZC SPCSWOMCD ALL
ACUS11 KWNS 141924 
SPC MCD 141924 
SDZ000-NEZ000-WYZ000-MTZ000-142200-

Mesoscale Discussion 0967
NWS Storm Prediction Center Norman OK
0224 PM CDT Mon Jun 14 2021

Areas affected...portions of eastern Wyoming...western South
Dakota...far northwest Nebraska

Concerning...Severe potential...Watch unlikely 

Valid 141924Z - 142200Z

Probability of Watch Issuance...20 percent

SUMMARY...Isolated strong thunderstorms are expected to gradually
develop and intensify over the next few hours. Large hail and
damaging gusts appear to be the primary threats with these storms.
Storm coverage is expected to be too sparse to warrant a WW
issuance.

DISCUSSION...Visible satellite and MRMS mosaic radar data show
convective initiation underway in proximity to the Big Horn
Mountains in northern WY, and Lawrence County, SD. Across portions
of eastern WY into western SD and far northwest NE, diurnal heating
is gradually eroding MLCINH per 15-19Z mesoanalysis trends. Moist
upslope low-level flow should also support isolated thunderstorm
development through the afternoon/early evening hours. Upper
50s/near 60 F surface dewpoints have been advecting northwestward
beneath 7.5-8.5 C/km low and mid-level lapse rates, contributing to
1500+ J/kg MLCAPE. While wind speeds are rather weak in the
surface-500 mb layer, gradual veering with height, along with some
speed shear above 500 mb, are contributing to 30-45 kts of effective
bulk shear. Transient supercells may manifest from the longer
lasting storms given the expected isolated coverage and
aforementioned thermodynamic/kinematic environment. 

The steep mid-level lapse rates will support large hail with any
robust updraft that can become established. Damaging gusts may also
occur with the stronger storm cores given the somewhat dry, mixed
boundary layer/steep low-level lapse rates. Still, a WW issuance
appears unlikely given the anticipated low storm coverage.

..Squitieri/Grams.. 06/14/2021

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

ATTN...WFO...UNR...CYS...BYZ...RIW...

LAT...LON   42300390 42260441 42290500 42460564 42620592 43270639
            44010697 44680760 44990761 45040689 44930555 44760457
            44470363 44250336 43670326 43000328 42830323 42300390 

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