One of the strongest El Niños on record could increase the chance of winter tornadoes forming in parts of the South, officials with the National Oceanic and Atmospheric Administration said Thursday.
Unseasonably warm and moist conditions during the winter can set the stage for tornado formation, and those conditions can be expected during the winter of 2015-16, which is probably going to be influenced by the El Niño.
NOAA scientists said wetter-than-average conditions are likely from Southern California across Texas, the Gulf Coast and Florida and up the East Coast to southern New England.
Warmer temperatures are expected across much of the West and Upper Midwest.
NOAA scientists said the possibility of tornado formation over the Deep South, including Florida, would be “elevated” this year because of the likely conditions.
Winter tornadoes are not necessarily more powerful than twisters that form during the spring and summer, but they usually move faster. That can make them more deadly because it reduces the warning time and allows less time for people to get out of harm’s way.
The tornadoes move faster because the upper-level winds that produce tornado-spawning thunderstorms are faster during the winter.
A spate of winter tornadoes in February 2008 killed at least 50 people in Kentucky, Tennessee, Arkansas, Mississippi and Alabama. An El Niño was not present during that winter, however.
The current El Niño could have “a strong influence over our weather this winter,” said Mike Halpert, deputy director, NOAA’s Climate Prediction Center.
“While temperature and precipitation impacts associated with El Niño are favored, El Niño is not the only player,” Halpert said. “Cold-air outbreaks and snow storms will likely occur at times this winter. However, the frequency, number and intensity of these events cannot be predicted on a seasonal timescale.”
An El Niño occurs when the Pacific Ocean off the west coast of South America is warmer than usual. This sets in motion a chain of events that can affect temperatures and precipitation across the U.S.
NOAA scientists think the current El Niño is likely to continue through the winter and not dissipate before the spring of 2016.
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