After several quiet years, tornadoes have erupted in the United States over the last two weeks as a volatile mix of warm, moist air from the Southeast and persistent cold from the Rockies clashed and stalled over the Midwest.
On Monday, the US tied its current record of 11 consecutive days with at least eight tornadoes on each of those days, said Patrick Marsh, warning coordination meteorologist for the federal Storm Prediction Center. The previous 11-day stretch of at least eight tornadoes per day ended on June 7, 1980.
“We’re getting big counts on a lot of these days and that is certainly unusual,” Marsh said.
The National Weather Service had already received at least 27 more reports of tornadoes Tuesday, suggesting that the record for consecutive days would be broken once the official totals are in.
The US has experienced a lull in the number of tornadoes since 2012, with tornado counts tracking at or below average each year and meteorologists still working to figure out why.
The National Weather Service has received 934 tornado reports so far this year, up from the yearly average of 743 observed tornadoes.
More than 500 of those reports came in the last 30 days. The actual number is likely lower, however, because some of the reports probably come from different witnesses who spot the same twister.
Most of the confirmed tornadoes were rated as less-intense EF0, EF1 and EF2s on the Enhanced Fujita Scale. But 23 were classified as EF3 tornadoes, with wind speeds of 136-165 mph. The strongest confirmed tornado this year was the EF4 tornado that killed 23 people in Alabama in March.
So far this year, 38 people have died in 10 tornadoes in the United States, including a combined seven within the last week in Iowa, Missouri, Oklahoma and Ohio.