Pacific Ocean Temperature Influences Tornado Activity in US

http://www.sciencedaily.com/releases/2013/10/131017174043.htm

Oct. 17, 2013 — Meteorologists often use information about warm and cold fronts to determine whether a tornado will occur in a particular area. Now, a University of Missouri researcher has found that the temperature of the Pacific Ocean could help scientists predict the type and location of tornado activity in the U.S.

Laurel McCoy, an atmospheric science graduate student at the MU School of Natural Resources, and Tony Lupo, professor and chair of atmospheric science in the College of Agriculture, Food and Natural Resources, surveyed 56,457 tornado-like events from 1950 to 2011. They found that when surface sea temperatures were warmer than average, the U.S. experienced 20.3 percent more tornados that were rated EF-2 to EF-5 on the Enhanced Fuijta (EF) scale. (The EF scale rates the strength of tornados based on the damage they cause. The scale has six category rankings from zero to five.)

McCoy and Lupo found that the tornados that occurred when surface sea temperatures were above average were usually located to the west and north of tornado alley, an area in the Midwestern part of the U.S. that experiences more tornados than any other area. McCoy also found that when sea surface temperatures were cooler, more tornadoes tracked from southern states, like Alabama, into Tennessee, Illinois and Indiana.

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