For 12 consecutive days, the government's Storm Prediction Center has logged reports of at least eight tornadoes daily, a destructive and impressive streak that constitutes a record -- at least for now.
"The fact that it's been persistent is unusual, but not unprecedented," said Bill Bunting, chief of the forecast operations branch at the storm center, in Norman, Okla.
"What's unique about this year is that we have had day after day of severe storms in the same areas," he said. "And you're going to have another one today."
He said a stubborn pattern in the upper atmosphere has been particularly conducive to setting off the severe storms that spawn tornadoes. On Monday, 77 were reported.
As for the U.S. 12-day record, Bunting cautioned that the data is preliminary and that it would take a few months to verify the sightings. He said some of the reports actually might be multiple sightings of the same tornado.
In addition, it is difficult to compare the volume of tornado reports today with those of the past. He said the closest comparable period would have been an 11-day streak of 10 or more tornadoes in 1980.
But the level of radar sophistication, development, social media, and pervasiveness of image-recording equipment continues to undergo quantum changes.
As for the hand of worldwide warming, tornado specialists point out that tornadoes are idiosyncratic storms that get their ferocious spin from a complicated matrix of conditions.
"It's not a cop-out," Bunting said. "We just don't know."
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