Posted at: 08/22/2013 7:06 PM
Updated at: 08/22/2013 7:21 PM
Quite the punch of heavy rain and strong thunderstorms this morning, especially in Minnesota. Thunderstorms from Iowa drifted north and strengthened from 5 to 8 am. The heaviest rain fell in Dodge & Olmsted counties in southeast Minnesota where portions of the area saw just under 4”, but the rest of Minnesota and Iowa saw around 0.25”.
The rain became too much to handle for portions of downtown Rochester where localized street flooding was common for the morning commute. The Mayo Clinic Charlton building had water sweep in on its subway and first floors. A flash flood warning was issued for a small area in Olmsted county including Rochester where reports of 1” per hour of rain were reported in addition to wind gusts at 50 mph and pea size hail.
Flooding wasn’t the only weather danger occurring. A microburst moved through Eyota this morning as well. Simply put, a microburst is a rush of cool air fanning out at the surface. A downburst accompanies every thunderstorm (that is why we feel cool air as thunderstorms pass), but it needs to have damaging winds to be classified as a microburst. Wind gusts can reach 150 mph, however wind speeds around 50 mph likely caused this morning’s damage. Microbursts are also very localized events impacting less than 2.5 miles and lasting for less than 5 minutes. If they last longer or affect a larger area they are considered macrobursts.