A derecho is a widespread fast moving squall line of thunderstorms. On average it travels 60 MPH taking approximately 12 hours to travel from Chicago to New York City. It accompanies mainly high winds due to its speed, intense lightning/ thunder and downpour. Sometimes have a wind sheer that can produce a tornado. The shape usually is a bow echo (looks like a bow on radar) or backwards "C."
di weirdalfan1980 25 giugno 2013