Mesoscale Discussion 1471
NWS Storm Prediction Center Norman OK
0531 PM CDT Thu Aug 10 2017
Areas affected...Portions of the upper Great Lakes region
Concerning...Severe Thunderstorm Watch 445...
Valid 102231Z - 110000Z
The severe weather threat for Severe Thunderstorm Watch 445
SUMMARY...A threat of damaging winds and large hail will likely
continue for at least a few more hours this evening, primarily
across/near southern portions of WW 445.
DISCUSSION...Strong to severe thunderstorms have evolved primarily
towards eastern and southern parts of WW 445 early this evening,
aided by broad ascent from a compact shortwave trough currently over
Wisconsin and upper Michigan. The strongest ascent will spread east,
in turn taking convection over Wisconsin and Lake Michigan towards a
less favorable thermodynamic environment. As such, these storms will
likely decrease in intensity as they spread towards lower Michigan.
Farther south, higher boundary-layer moisture is promoting around
1000-1500 J/kg of MLCAPE, supportive of more intense convection.
Along the southern periphery of the mid/upper wave, surface flow is
more veered; in turn, storm evolution this evening may be
characterized by transient supercells and multicellular modes, with
damaging winds the primary threat. However, favorable deep-layer
shear, owing to vigorous westerlies aloft (upwards of 50 kt at 500
mb), will encourage occasional updraft organization/rotation in
stronger, semi-discrete cores. Therefore, a few instances of large
hail will remain possible across/near southern parts of WW 445 this