AccuWeather.com reportsfollowing a near-record number of tornadoes in 2011, an active severe weather season with above-normal tornadoes is expected in 2012.



There were 1,709 tornadoes in 2011, falling short of the record 1,817 tornadoes set in 2004. In comparison, the average number of tornadoes over the past decade is around 1,300.



Last year ranks as the fourth most deadly tornado year ever recorded in the United States.



In 2011, there was a very strong La Niña, a phenomenon where the sea surface temperatures in the central and eastern Pacific around the equator are below normal. As a result, there was a very strong jet stream, which is a key ingredient for severe weather.



Often in a La Niña year, the "Tornado Alley" shifts to the east, spanning the Gulf States, including Mississippi and Alabama, and the Ohio and Tennessee valleys. During the extremely active severe weather season of 2011, many tornadoes touched down east of the typical "Tornado Alley," which stretches from Texas to Kansas.

Twisters frequently hit Texas to Kansas during the spring as warm, humid air from the Gulf of Mexico clashes with drier air coming out of the Rockies.



Above-normal tornadoes are anticipated again this year.



Warmer-than-normal Gulf of Mexico water is a key component to the active severe weather season anticipated in 2012. There will be a sufficient supply of warm and humid air to fuel supercell thunderstorms, the type of storms that spawn strong tornadoes, because of the warm Gulf water.



The weak to moderate La Niña during this winter is much weaker compared to last winter, and it is weakening even more now.

There is evidence that warming is occurring in the equatorial Pacific, so the El Niño/La Niña Southern Oscillation (ENSO) is expected to turn neutral by April. In other words, the temperatures in the central and eastern equatorial Pacific will be near normal by spring.