South Dakota Mesoscale Discussion

Areas affected…portions of western Nebraska and the Nebraska
Panhandle and into adjacent southwestern South Dakota

Concerning…Severe potential…Watch possible

Valid 041926Z – 042130Z

Probability of Watch Issuance…60 percent

SUMMARY…Severe risk is expected to gradually increase across the
discussion area, which may warrant WW issuance.

DISCUSSION…Latest radar and visible satellite loops show rather
rapid storm initiation over southeastern Oglala Lakota county in
South Dakota, near a well-defined, remnant outflow boundary that
continues to advance southeastward toward/into the Nebraska
Panhandle. Near and ahead of the outflow, moderate destabilization
has occurred in conjunction with diurnal heating, with 2000 to 2500
J/kg mixed-layer CAPE indicated.

With observed and model forecast data showing low-level flow
veering/increasing with height, shear profiles supportive of
organized convection should support robust updrafts. This confirms
the visual appearance, and rapid intensification, of the
aforementioned/developing storm per radar/visible imagery.

While the cell remains isolated at this time, cu development
continues to increase just to the southwest — i.e. near and just
across the Nebraska/Wyoming border. Recent HRRR runs continue to a
gradual increase in storm coverage in this area, which the evolving
cu field seems to support. As such, it appears an increase in
convective coverage and intensity will likely occur over the next
couple of hours, possibly warranting Severe Thunderstorm Watch

..Goss/Dial.. 08/04/2019

…Please see for graphic product…


LAT…LON 41950370 42430365 43100267 43600115 43210059 42280019
41420051 41490270 41950370

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