Tuesday, June 24, 2014

Heavy Rain Update: Flash Flood Potential VERY HIGH

The ground is saturated from Monday's rain. An additional 1-3" of rain a very good possibility over the next 18 hours. Flash Flooding is the greatest concern. FLASH FLOOD WATCH FOR ALL OF NORTHERN OHIO UNTIL 10PM THIS EVENING. THIS MIGHT BE EXTENDED.




Central Great Lakes sector loop


Why The Surprise Tornado In Brunswick, Ohio?

Yesterday (Monday 6-24-2014), a tornado touched down just south of RT. 303 in Brunswick without a tornado warning. (Note: A severe thunderstorm warning was issued by the NWS). What caused this tornado to develop? Was this tornado something that could have been foreseen? What happened?

Check out the radar loop I uploaded from yesterday (Monday evening).

Notice two elements: 1) The line or boundary just south of Lake Erie and 2) The other boundary that moved north of Wooster. These boundaries are called "outflow boundaries" or a "Gust Front". Put simply, these boundaries are like waves that propagate away from a boat that passes In this case, The boundary marks an area of sinking, cooler air that moves away from the first line of storms northeast of Cleveland. Some look like this:

As the boundary moved south away from Lake Erie (and north from near Wooster) it acted as a super-small scale cold front lifting the warm/moist air ahead of it enhancing the storm cluster already moving in from the west causing rotation and ultimately a tornado with winds of at least 110 mph. The convergence of these two boundaries and the established storm from the west (which already had minimal rotation according to the Cleveland NWS) provided the necessary ingredients for a rapidly developing tornado. All of this occurred within 10-15 minutes. Something like this is nearly impossible to forecast.