South Dakota Mesoscale Discussion

Areas affected…Central North Dakota and South Dakota

Concerning…Severe Thunderstorm Watch 619…

Valid 252258Z – 260100Z

The severe weather threat for Severe Thunderstorm Watch 619

SUMMARY…Threat for large hail and strong/severe wind gusts will
continue into the early evening in portions of WW 619. Storms within
North Dakota have generally grown upscale which will limit the
severe hail threat. Activity in increasing in central South Dakota.
Eastern extent of the threat will be limited by low-level
stratus/stable air to the east. Local extension in area of WW 619
may be needed if storms in southwestern South Dakota increase in

DISCUSSION…A few supercell structures produced several reports of
severe hail, some of which were 2 inches, across central North
Dakota in the last two hours. Much of this activity has congealed
into a linear cluster north of Bismarck. This cluster will likely
pose some threat of severe hail and strong/severe wind gusts as it
drifts slowly southward within the axis of greatest buoyancy.
Activity will be limited in how far east it can progress with very
stable air in place. Overall severe threat will diminish from west
to east in North Dakota as the cold front continues to move east.
Farther south, storms have been slow to initiate but activity has
increased within the pre-frontal trough west of Pierre. More
nebulous forcing for ascent will likely mean less storm coverage
than points northward. Nevertheless, a narrow corridor of 1500-2000
J/kg and 35-40 kts of effective shear will support a threat for
large hail and strong/severe wind gusts into the early evening.

Storms within the Black Hills and SD/NE border have generally
remained below severe limits to this point. Should this activity
increase in intensity, a local areal extension of WW 619 may be

..Wendt.. 08/25/2019

…Please see for graphic product…


LAT…LON 46330183 48200172 48860125 48970042 48859951 47479889
45699889 44719917 43909941 43499990 43440098 43780165
44560187 46330183

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