Blame it on La Nia

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PHOENIX – So far in 2011, there have been more than 1,200 tornadoes in the United States, more than 500 people are dead and there have been 4 EF-5 tornadoes, the strongest storms with winds in excess of 200 miles per hour.

To put that in perspective, in the past 10 years, there have only been two, that’s right, two EF-5 tornadoes in the U.S.

Scientists are beginning to think you can, to some extent, blame it on La Niña or at least the quick, recent exit of the pattern that brings cooler than normal sea temperatures to the Pacific equatorial regions.

La Niña is a stabilizing force on the jet stream and pushes it into Canada. When that went away, the jet stream started zig-zagging all over the place.

Also to blame is the contrast between warm and cold regions of the U.S.

You may recall last winter we had record snowfall and snow packs across the continent. That helped to keep northern air even colder.

In contrast, water in the Gulf of Mexico is running 2 to 3 degrees warmer than normal so there’s a bigger contrast this year between the cold and warm air masses.

Finally, the overall numbers of tornadoes might be too high. Many funnels may have been counted more than once.
That’s something that will be sorted out later this year.

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