Tornadoes struck the United States from coast to coast yesterday, with reports of twisters in Massachusetts and California as well as in the usual hotbed of Tornado Alley.
Massachusetts was hit the hardest, with four reported deaths, making the tornado outbreak the state's deadliest in 16 years. On the other side of the country, two tornadoes touched down in rural Northern California, and the report of a third was under investigation. Kansas and Nebraska also saw tornadoes, including reports of a rain-wrapped twister.
As with earlier violent tornado outbreaks, the jet stream got most of the blame for stirring up the weather.
"They're all kind of related," said meteorologist Steve Goldstein, with the National Weather Service in Sacramento, Calif. "What we've been seeing this year is really strong shear, meaning winds turn with height. That's the same dynamics they got with the big monster storms in Alabama and Missouri."
That strong wind shear — created by a rogue, turbo-charged jet stream carrying some of the coldest air on the planet — mixed with ground heat during the hottest part of the day, fueling yesterday's outbreak in California, Goldstein told OurAmazingPlanet.
As the jet stream blows eastward, storm hot spots can form across the country where hot, soupy air mixes with cooler air. That's exactly what happened yesterday to form tornadoes from coast to coast.
"That kind of spacing for springtime is not unusual," said John Harrington Jr., a climatologist with Kansas State University. "The thing that's been unusual this spring is the sheer number of tornadoes."
Massachusetts had not seen a tornado since 2008 until yesterday, when 18 were reported. That number is likely to go down as experts rule out duplicate sightings.
The last time a deadly tornado struck Massachusetts was May 29, 1995, according to the National Climatic Data Center. That tornado, an EF-4 on the tornado damage scale, killed three people in the town of North Egremont. [Related: The Tornado Damage Scale in Images ]
Yesterday "wasn't one of those typical days" in Tornado Alley, where textbook tornadoes typically form, said Vanessa Pearce, a meteorologist with the National Weather Service in Wichita, Kan. But the instability in the atmosphere was enough to stir things up. Brief rope tornadoes — thin, wispy twisters — were reported in Nebraska, and six tornadoes were reported in Kansas, including a rain-wrapped twister, which can be deadly because they are nearly invisible. No injuries were reported in either state.
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