Derecho: Strange Name - Big Storm
A small cluster of thunderstorms developed in northern Illinois this past Friday June 29, 2012 between 9 and 10 am CDT. By 1:45 PM that same cluster of storms had produced a wind gust measuring 91 mph at the Fort Wayne, IN airport. This complex raced eastward at an average speed of 60 mph while producing widespread major damage stretching some 600 miles from Indiana to the Atlantic coast. As of this moment, reports indicate that at least 22 fatalities occurred due to the storm, and as many as 3 million customers were without electricity after the storm had passed. Falling trees on vehicles and homes due to the extreme winds killed the majority of those 22. This especially destructive, long lasting line of thunderstorms is known as a derecho, and this particular derecho became one of the most damaging in recorded history.
The primary distinguishing characteristics of a derecho is its intensity, longevity, and duration. While derechos are certainly not unheard of, they aren't exactly common either. The SPC in Norman, Oklahoma provides details about them here: http://www.spc.noaa.gov/misc/AbtDerechos/derechofacts.htm Interestingly, the area that is most climatologically favorable for a derecho is northeast OK, southwest MO, and northwest AR.
Last Friday a record-breaking June heat wave for many locations across the Tennessee valley and mid-Atlantic areas had helped provide one of the ingredients that fueled the storms this past Friday. In fact, temperatures soared to 109° in Nashville, TN and 104° in Washington, D.C. However, it is absolutely false and absurd to assume that this derecho or heat wave was a result of anthropogenic (manmade) global warming, as some have been quick to point out. The first mistake one can make with respect to blaming any singular weather event on climate change is by not understanding the basic definitions of weather and climate to begin with. Not to mention it was the combination of the heat/moisture south of a stationary boundary, and much cooler air to the north of that boundary that was essential to both the intensity and track of the derecho. Without the change in temperature over the boundary, the jet stream would have been much weaker resulting in less intense storms. Furthermore, if the only ingredient needed for derechos were record breaking temperatures I'm fairly certain that there wouldn't be much left of the southern plains after the summer of 2011.