(UPDATED*) Gainesville Times, Wash. Post: Does drought cause tornadoes to wither too?
The Gainesville Times‘s Melissa Weinman on Sunday reported what one might guess from instinct or first principles, but apparently nobody had reason to think about it. It surprised a University of Georgia researcher when it popped out of some statistics he gathered on tornadoes in the US Southeast. In and around Atlanta, he found, if the latter half of a year is dryer than normal, the following spring’s tornado season is almost always light. Now he and colleagues will see if the pattern holds for other areas as well. It is in Environmental Research Letters. The Tracker doesn’t know his fugacity from a latent heat sink, but this seems to make some sense – thunderstorms arise from convection and condensation in moist air, so dry soil might mean less moisture for the updrafts. Or not. Just guessing.
This news has another wrinkle in the media. That striking image to the upper right was taken in Wyoming early this month during an exercise called VORTEX2 sponsored by NOAA’s Storm Prediction Center. On the Washington Post‘s site is long and admirably detailed write-up of that by enviro writer and weather blogger Andrew Freedman. He joined researchers for the field study, no doubt hoping to be there when they came across some dreadful F-awful funnel lofting cows as it darted from the black skirt of a supercell billowing over the western plains. No such luck. The pic is the ONLY tornado the effort, with its fleet of storm chasers, captured and Freedman was there. It was, he writes, the most intensely observed tornado, scientifically speaking, ever. But overall the spring tornado season in the Great Plains may have been the sparsest in at least half a century. Freedman cites the Georgia study as a pertinent, possible, partial explainer, too. Really partial. Last year was rainy in parts of the western U.S. that VORTEX2 prowled so as a data point, it may be problematic.
Freedman provided a dramatic photo album from VORTEX2 in an earlier post. Give me California and earthquakes any day. Just thinking about being in the way of one of those twisters gives me the vapors.
*UPDATE: A prominent daily writer of science news tells The Tracker that he looked into the story and, consulting with a climatologist of note, demurred because of a strong hunch that while there may be true correlation between drought and tornado, it reflects neither cause-and-effect nor mere coincidence. A stronger possibility is that both are succumbing to the influence of the El Nino – Southern Oscillation in the far Pacific. ENSO clearly tilts the odds back and forth on drought all across the US. There also are suggestions it changes the likelihood of tornadic collision among air masses. So, in places drought may precede or accompany fewer tornadoes but that does not mean it is the cause. It’s like – um, well, the Fourth of July brings more sunburns from going to picnics and watching parades. It’s a day when more Americans eat hot dogs. But that does not mean hot dogs cause sunburns. And for both cases, only more research can say for near-sure.
Grist for the Mill: U. Ga. Press Release ;
-CP
