Last year most of the tornado-related deaths happened in December. In fact during Christmas week we saw a tornado report every day for a week. This has never happened before in December.
North Texas also experienced the strongest and deadliest tornado ever in December: an EF-4 packing winds of 180 mph in Dallas County.
It became the second deadliest December tornado outbreak for the U.S. The worst December tornado outbreaks and four of the five largest winter tornado outbreaks all occurred during strong El Nino events.
If the Eastern Pacific was cooler than average, called La Nina, the numbers and frequency of tornadoes are usually much higher than El Nino years.
The main storm track is more active and energized producing more tornadoes in the heartland in the spring and fall.
But during El Nino, the tornado threat lingers into winter. The main storm track lifts to the north & the tropical flow takes over. That sends systems over the south more often during this time of year.
These lows pick up the spring-like air mass and set off violent storms. The interaction of wind coming off the Gulf & Pacific will sometimes make the air turn and allow tornadoes to form.
The number of tornadoes may be lower during El Nino years but with all the available moisture, warmth and energy stronger tornadoes happen in the winter and are more dangerous as they move faster plus people don't expect them.
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