|Mesoscale Discussion 728|
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Mesoscale Discussion 0728
NWS Storm Prediction Center Norman OK
0213 AM CDT Tue May 16 2017
Areas affected...southeast South Dakota...northern Iowa...southern
Minnesota and western Wisconsin
Concerning...Severe Thunderstorm Watch 218...219...
Valid 160713Z - 160845Z
The severe weather threat for Severe Thunderstorm Watch 218, 219
SUMMARY...Though some threat for mainly hail persists, overall
threat is becoming increasingly marginal. Severe thunderstorm watch
218 is scheduled to expire at 08Z, and no additional WW is expected.
DISCUSSION...Storms will continue within zone of isentropic ascent
north of warm front from southeast South Dakota through southern
Minnesota and western Wisconsin supported by a strengthening
low-level jet and a northeast-advancing shortwave trough. Other
storms are developing along an eastward-moving outflow boundary over
a portion of western Iowa. Tendency has been for temperatures in the
800-700 mb layer to gradually warm which has resulted in stronger
convective inhibition for parcels originating at or below 850 mb.
This suggests updrafts are probably rooted in layers above 800 mb
where lower theta-e air is resulting in weaker updrafts. Though
mid-level lapse rates and MUCAPE are sufficient to support
marginally severe hail, overall threat appears limited.
...Please see www.spc.noaa.gov for graphic product...
LAT...LON 43539789 44109662 44809404 44319076 43259142 43029446
42419580 42759697 42939756 43539789
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