This is an archived article and the information in the article may be outdated. Please look at the time stamp on the story to see when it was last updated.
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 continues. 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 evening.