South Dakota Mesoscale Discussion

Areas affected…far southern North Dakota into central South Dakota
and Nebraska

Concerning…Severe Thunderstorm Watch 556…

Valid 062319Z – 070115Z

The severe weather threat for Severe Thunderstorm Watch 556

SUMMARY…The threat for damaging hail and wind continues, and will
likely extend south of watch 556. A new watch is likely for parts of
southern South Dakota into Nebraska by about 01Z.

DISCUSSION…Storms that formed near the surface trough have
solidified into large cells, with supercell characteristics at
times. Forecast soundings show a deep layer of steep lapse rates
owing to heating and cool temperatures aloft. Low-level winds are
weak currently, but hodographs are quite long with strong northwest
flow aloft.

Ongoing storms are currently within the surface theta-e axis, which
extends from the central Dakotas into central NE. East of this axis,
the air mass is much less unstable near the surface high, from
southeast SD across eastern NE and points east.

In the near term, storms are expected to continue
south/southeastward near the instability gradient, remaining mainly
cellular. Very large hail and localized wind damage will be
possible. Increasing southwesterly 850 mb winds this evening may aid
lift into eastern SD and NE, but the warm advection profiles are not
to be very pronounced. As such, the corridor of maximum threat
should generally extend south/southeast from the ongoing storm
cluster near the MO River in central SD.

..Jewell.. 08/06/2019

…Please see for graphic product…


LAT…LON 44420068 44429825 43919791 43079760 42119749 41289728
41229730 41069785 40949860 41069907 41339949 42079988

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