Most people have never heard of the term "Derecho" until this past week. A Derecho is a violent, long lasting straight line storm system that can reach severe limits. Its a term that Meteorologists rarely use because its somewhat technical and more so, because they don't occur very often. Unlike ordinary severe storms that pop up typically in summer, these are large complexes that can travel hundreds of miles. Derechos behave like a larger scale weather system which makes they especially powerful and potential destructive. Instead of slowing down, Derechos can GAIN forward speed which makes the forecasting that much more difficult.
This is what happened on Friday; a smaller scale event happened yesterday. The potential still exists for a repeat over the next few days.
CURRENT OHIO VALLEY RADAR
Great swirl photo taken in Sandusky as the storm moved through
Notice how fast the line of storms moved from 2PM to 8PM.
75% of West Virginia was without power over the weekend.
The line continued through D.C. and off of the east coast