The most intense week of twisters in US history hits hard - and highlights new efforts to be prepared.
As communities struck by last week's tornado outbreak echo with the rumble of front-end loaders and the metallic thud of debris hitting dumpsters, weather forecasters are calling it the most intense week for twisters in US history.
The week-long onslaught was, perhaps, the tornado-watcher's equivalent of "The Perfect Storm." The set of conditions that led to outbreak are " not likely to happen not likely to happen very often in our lifetime," says Harold Brooks, a researcher at the National Severe Storms laboratory in Norman, Okla. "This was pretty high-end, even for severe-storm fans."
Yet for all its destruction, the outbreak also appears to be vindicating the country's investment in research and hardware to improve forecasts and warnings.
During the 1990s, the National Weather Service (NWS) spent $4.5 billion upgrading everything from its weather radar to computer models that help forecasters. The "improved radar data and improved model data really helped us as far as last week was concerned," says Dan McCarthy, a meteorologist with the NWS Storm Prediction Center in Norman, Okla.
"Everyone is comparing last week to 1974," when a "super" tornado outbreak April 3-4 triggered 148 tornadoes that carved a path of devastation 2,500 miles long, says Mr. McCarthy.
That outbreak killed 330 people and injured more than 5,000. Another 10 tornadoes would form before that week was out.
By contrast, 384 tornadoes struck 19 states last week, killing an estimated 43 people. The dramatic shift in fatality rates may be of little solace to those who lost friends or relatives in last week's storms. Still, the low casualty figure for the number of twisters last week remains "an incredible ratio," Mr. McCarthy says.