It gets windy in severe thunderstorms. Matter of fact, one of the criteria for calling a thunderstorm severe is that it could have wind gusts of 60+ mph. But today's thunderstorm over Greater Portland was a little different. The wind was a result of a downburst.

The downburst occured when an area of heavy rain and some hail caused lots of air to rush downwards toward the surface of the earth. When the air got there, it had no where else to go, so it spread out in all directions. The air was moving very quickly, and it stayed moving very quickly. We've seen reports of wind gusts up to 57 mph today in Portland (Peaks Island), not to mention numerous large limbs down in the Portland area with power outages around 4,000 in Portland at one time.

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If a downburst occurs over an area less than about 2.5 miles in diameter, we classify it as a microburst. If it occurs over a larger area, then it's a macroburst. We're still looking in to that part.

It's important to note that a downburst is NOT a tornado, but it can produced damage like one. A tornado has to have rotation, while a downburst is straight line winds.