Tornado-chasing scientists capture a supercell storm in all its glory

By Alexandra Witze

Web edition: October 13, 2010

DENVER — It’s always easy to tell when you’re at a conference of the American Meteorological Society. Fliers advertise book signings on the history of broadcast meteorology. “Storm video nights” highlight everyone’s favorite destructive storms. And the hotel-lobby chatter about tomorrow’s weather? You know you can trust it.

True to form, this year’s AMS conference on severe local storms featured a topic dear to all Discovery Channel junkies — early results from the VORTEX2 tornado-chasing experiment. This is the sort of research you’ve seen endless documentaries on, with more than 100 scientists and 40 instrument-laden vehicles chasing tornadoes across the Great Plains during the summers of 2009 and 2010. (No Bill Paxton or Helen Hunt, though.)

Early on October 12, project scientists unveiled findings on the best-documented storm they’ve ever caught: a twister, rated 2 on the enhanced Fujita scale, that scampered across a barren stretch of Goshen County, Wyoming, on June 5, 2009.

It was the first time researchers have documented the birth, life and death of a twister from a supercell thunderstorm in such detail, said Roger Wakimoto, a principal investigator for VORTEX2 and head of the National Center for Atmospheric Research in Boulder, Colo. Two mobile Doppler radars captured it from different directions, while fleets of scientists and amateur stormchasers photographed it from nearly all angles.

By itself, the Goshen County tornado was nothing exceptional. It started up in late afternoon, its rotation picking up well before the funnel cloud became visible and started to reach down to the ground. The funnel itself had a double ringlike structure, each ring its own cloud of debris, said Wakimoto. The twister wobbled across the ground in a very nonlinear path, leaving behind nothing worse than downed tree limbs.

But the value of such observations is in sharpening scientists’ knowledge of how tornadoes are born and grow. “It’s the details we’re starting to fill in, the nitty gritty stuff,” Karen Kosiba, a postdoctoral researcher at the Center for Severe Weather Research in Boulder, told the audience.

What every Twister fan thinks he knows about meteorology is indeed true: it’s those details that make the difference in knowing which storms will blow up into killer tornadoes and which ones will just blow over.