SPC MD 1135

MD 1135 CONCERNING SEVERE THUNDERSTORM WATCH 339... FOR NORTH-CENTRAL SOUTH DAKOTA.

Mesoscale Discussion 1135
NWS Storm Prediction Center Norman OK
0802 PM CDT Tue Jul 07 2020

Areas affected...north-central South Dakota.

Concerning...Severe Thunderstorm Watch 339...

Valid 080102Z - 080300Z

The severe weather threat for Severe Thunderstorm Watch 339
continues.

SUMMARY...A growing cluster of storms should continue to move into
north-central South Dakota and pose a threat for strong wind, and
perhaps hail. A downstream watch may be needed before 02Z.

DISCUSSION...Radar and satellite trends over the past half hour have
shown a growing cluster of storms across southwest SD, east of the
Rapid City, SD area. Initial concerns regarding lingering inhibition
and storm maintenance have been mitigated due to this recent storm
intensification. This trend is likely due to thunderstorm outflows,
aided by 850 mb warm advection, overcoming inhibition and lifting
parcels to their LFCs as storms move into a more favorable
environment for organized convection (featuring upwards of 3000 J/kg
MLCAPE, steep mid-level lapse rates, and 50-55 knots of effective
bulk shear per recent RAP mesoanalysis). Lift within the 850 mb warm
advection regime should continue to support thunderstorm development
for the next few hours.

Deep layer shear oriented largely along the warm advection axis
should support a gradual transition from discrete/semi-discrete
storm modes into more linear segments. This should favor a wind
threat downstream, though instances of severe hail are possible. A
downstream watch may be needed by 02Z for portions of north-central
South Dakota to address these concerns.

..Moore.. 07/08/2020

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

ATTN...WFO...ABR...UNR...

LAT...LON   43680329 44470294 45500201 45670098 45580007 45080009
            44480013 44040050 43480151 43470233 43680329 

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