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2012 Tornado Number High So Far; Will That Trend Continue?

By Meghan Evans, Meteorologist
April 11, 2012; 9:07 AM

So far 2012 has been a very active tornado year compared to last year and the average annual trend back through 2005.

According to graphs provided by the Storm Prediction Center, there were 416 preliminary tornado reports through April 9, 2012. Compared to past years, this is a very busy start to the severe weather and tornado season.

The average annual trend from 2005-2011 indicates that there would normally be about 332 tornadoes through April 9. During the time period from Jan. 1-April 9, 2011, there were 92 tornadoes.

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Two recent years where the number of tornadoes surpassed this year were 2008, when 591 tornadoes touched down through April 9, and 2006, when 483 tornadoes touched down through April 9.

The March 2 Tornado Outbreak was the biggest outbreak of 2012 so far with 132 tornado reports. At least 39 people were killed by the dangerous tornadoes that leveled entire towns such as Marysville and Henryville, Ind.

Rare March tornadoes have touched down as far north as southeastern Michigan this year, while big metropolitan areas such as Dallas and Fort Worth have also been targets.

Why Has 2012 Started Out So Volatile?
The above-normal warmth of the Gulf of Mexico is a big factor in the large number of tornadoes early this year.

"Water temperatures in the Gulf of Mexico did not cool off this winter without cold air masses reaching the Deep South," AccuWeather.com Expert Senior Meteorologist Dan Kottlowski said.

The warmer-than-normal temperatures in the Gulf of Mexico mean any time the flow switches out of the south, warm and humid air is drawn into the U.S.

Warm, moist air is a key ingredient for thunderstorms that are strong enough to spawn tornadoes.

"Ground temperatures are also warmer than normal... This is one of very few years of recent, where the ground was not frozen across the Ohio Valley," Kottlowski explained. When the ground is cold or frozen it creates an inversion, which means temperatures rise with rising altitude. An inversion creates a stable atmosphere and can prevent thunderstorms from forming or allow only higher-based thunderstorms to develop.

"Lower-based thunderstorms create much more opportunity for tornadoes," Kottlowski added.

Will 2012 Remain Active with Tornadoes?
Besides the tornadoes that hit the Dallas area so far this April, it has been a slow start to the month as far as tornadoes goes. There have been 26 tornado reports so far this April. The three-year average number of tornadoes during the month of April is 371.

Back in late February, the AccuWeather.com Long-Range Forecasting Team expected an above-normal number of tornadoes in 2012 with two peaks in the severe weather season. The first peak was forecast for March, during which 225 tornadoes touched down. The three-year average number of tornadoes for the month of March is 74.

A second peak is expected during April as the weather pattern makes another change.

"Severe weather will get more active by the middle of April," according to Jack Boston, AccuWeather.com expert senior meteorologist and long-range forecaster.

"The pattern will get more progressive," Boston said, meaning more storms will cross the country.

Kottlowski weighed in, agreeing that "April is one of the more volatile months."

There were 416 preliminary tornadoes reports from Jan. 1-April 9, 2012. That is above the average number of tornadoes from 2005-2011 during the same time period. Graph from the Storm Prediction Center.

Plot of the annual running total of U.S. tornadoes. Two recent years where the number of tornadoes surpassed this year were 2008, when 591 tornadoes touched down through April 9, and 2006, when 483 tornadoes touched down through April 9. Graph from the Storm Prediction Center.

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