Friday, June 03, 2011

Tornadoes In Massachusetts = Not Unusual

The recent tornado that hit Springfield, Mass has spawned a number of stories pushing the meme that there was something "unusual" about there being a twister in the Bay State:




Tornadoes in Springfield, Mass. A tornado warning in northern Rhode Island. The highest death toll from tornadoes since the National Weather Service began tracking twisters more than 60 years ago.

It’s easy for the casual observer to connect this spring’s catastrophic weather to climate change, but local scientists caution against making that leap.

Weather is a local phenomenon, says Bradley Moran, an oceanography professor at the University of Rhode Island’s Graduate School of Oceanography. Climate refers to changes in the weather over decades, centuries, even millenniums.

Springfield’s tornadoes were unusual, yes. When you look at the unfurling history of climate, however, Moran says that these storms are little more than “a tiny spike.”

While, in one sense, I'm heartened that AGW wasn't automatically trotted out as the answer to why bad things happen to good people, I'll still note that the above is simply wrong. It's wrong because tornadoes are not unusual for Massachusetts.

Here is the NOAA data which looks at tornado incidence per 10,000 square miles:



So, there are more tornadoes in Massachusetts per 10,000 square miles then there are in North Dakota or Minnesota or Kentucky or Michigan. It has the same per 10,000 square mile incidence rate as Ohio, Tennessee and Wisconsin. In none of those states are tornadoes considered "unusual." In fact, if you look at the rate of large tornadoes per 10,000 square miles you'll discover that Massachusetts has the same per 10,000 square mile incidence rate as Texas. (Surprising but true.)

People are being thrown by the fact Massachusetts is such a small state and therefore the total numbers of tornadoes are relatively small. However, an apples to apples comparison shows that calling them "unusual" is simply untrue.

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