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Twister, a vortex on the move.
The U.S. experienced fewer tornadoes in the past three years than any similar span since accurate records began in the 1950s. Yet meteorologists aren't sure exactly why.
As this year comes to a close, about
150 fewer damaging tornadoes than average have hit the U.S., according to data from the Storm Prediction Center (SPC). Explanations for the decrease in twisters the past three years range from unusual cold to unusual heat, or just coincidence.
Despite the calmer than average years, deaths due to twisters remain near the average of 60 each year, with 68 killed in 2012, 55 in 2013 and 42 so far this year, according to the SPC. That pales in comparison with the 553 Americans killed by tornadoes in 2011.
So far this year,
just 348 EF-1 or stronger tornadoes have touched down across the country, marking the
third-lowest number on record. An average year sees about 500 EF-1 or greater tornadoes. A total of 364 EF-1 or stronger tornadoes touched down in 2012 and 404 in 2013.
EF refers to the Enhanced Fujita Scale of tornado intensity, which runs from EF-0 to EF-5. Most twisters that cause damage and deaths are EF-1 or higher, with wind speeds of at least 86 mph.
Harold Brooks, a meteorologist with the National Severe Storms Laboratory in Norman, Okla., said there's
no consistent reason for the three-year lull - the calmest stretch since a similar quiet period in the late 1980s - because weather patterns have varied significantly from year to year.
Comment: Interesting that the tornado experts won't hazard a guess as to the factors influencing the creation and intensity of the twister phenomena. Consider that the lack of West Coast storms that has magnified the drought conditions in California, and other coastal states, account in part for the decrease in large-scale weather systems that travel across the country. Low temperatures from recent "polar vortexes" has to be a factor (due to the global temperature downturn as we approach ice-age triggering conditions). And, the experts do not address the electrical component (charge rebalancing between the ionosphere and the Earth's surface) of tornadoes coupled with the effects of, and reasons for, the solar minimum (a less positively charged ionosphere causing a reduction in the electric potential differential). Perhaps they need to do some homework and come up with some answers.