Federal center is the eye on year's killer storms

NORMAN, Okla. - After this spring's record tornado outbreaks, shocking death tolls, and incomprehensible destruction, Russ Schneider might have figured he could wind up in his own bull's-eye.

But twice in one hour?

At the height of the afternoon commute Tuesday, May 24, a monstrous twister with winds up to 200 m.p.h. took aim at his subdivision. He rushed home from work, gathered up his wife and two children, ages 9 and 11, and drove them back to his office as the sirens screamed.

No sooner had Schneider secured them in the underground shelter than a second, nearly identical tornado spun toward the building - home of the U.S. Storm Prediction Center, where he is director.

The five-story brick-and-glass structure was made to take winds of about 165 m.p.h. Yet even as the tempest roared within a few miles, as the sky rained debris, as their lives and homes were threatened, the forecasters stayed at their computers on the second floor, issuing advisories on the mayhem that could be cooking two hours hence over in Tulsa.

The atmosphere is in a state of riot. The weather has gone crazy. And this is the locus of the lunacy.

The Storm Prediction Center is the national firehouse for all severe-weather alerts. A $5.2 million federal operation on the University of Oklahoma campus, it is the source of the life-and-death decisions on when and where to sound the alarm.

And the sirens have been going off as never before.

The Norman twisters followed by just two days the colossal tornado in Joplin, Mo. - which killed more than 140, the single deadliest tornado in 64 years - and by a month the assault on the South that claimed 317 lives in one day.

Though it peaks in May and June, tornado season runs 24/365. In just the first five months this year, 1,411 twisters were sighted, from Northern California to Caribou, Maine. Same period last year: 507.

Pennsylvania has had at least 25 to date, including two June 12 in York County and one in Philadelphia last month. In a typical year, fewer than 10 whirl through. So far, New Jersey has been twister-free (leaving it nonetheless to quake in its flip-flops over a hurricane season predicted to be hyperactive).

Tornadoes have killed 533 in the United States this year - already the highest death toll since 1936, when the word tornado was banned from government forecasts for fear of inciting panic. Severe weather has wreaked a conservatively estimated $32 billion in property damage. That's five times the annual average.

"By any measure, this has been a very historic season," said Schneider, 52, a meteorologist who joined the center in 1997 and became the boss in August. "We really don't throw around historic loosely."

For the elite clique of 35 twister predictors in Norman, progress can be measured in minutes. Twenty years ago, warnings were issued an average of seven minutes before sightings. Today, that window has opened to 14.

Schneider noted with some pride that the storm center had a watch out for every fatal outbreak this season, but then conceded that wasn't much comfort.

"There's a sinking feeling when you know what's transpiring," he said. "Sometimes people can't get out of harm's way."

In a high-tech hub where data pour in from satellites, surface instruments, radar, and computer models, Greg Carbin begins his day by spreading a plain white map of the United States across his desk and grabbing his "pencil box," a carton of colored markers.

For 40 minutes, Carbin - the warning coordinator - plots temperatures, wind speeds, and moisture levels on the map. Blue for the winds in the high atmosphere, red for lower-level winds. If the blue and red go in different directions, that's trouble. The atmosphere can spin up tornados.

"I cannot begin the forecast process, seriously begin it, without starting at this point," Carbin said.

But why the elementary school art supplies when taxpayers have given him the most sophisticated equipment on Earth?

"There's something about getting your hands in the data that allows you to assimilate information in a different way from just looking at a computer screen," he said. Younger colleagues, he added, don't necessarily agree.

Each eight-hour shift is staffed by four or five forecasters prowling for pandemonium in the nation's skies. Lead forecaster David Imy had posted himself at a barricade of 11 monitors pulsing with streaks and blobs of red, green, blue, and white. They showed lightning strikes, radar images, and computer-model outputs. At his side were the pencil box and hand-colored map.

It was nearing the witching hour, when storms typically fire up, incited by a day of solar heating. The forecasters were looking for signs of volatility at every layer of the atmosphere. One full of water vapor and high energy is dangerous. If conditions force air to rise rapidly, powerful storms can be set off.

Imy was focused on a cluster of strong storms from Boston to West Virginia pressing toward Philadelphia, and another batch menacing Kansas City, Mo.

At 2:35, he issued a severe-thunderstorm watch for an area that covered Philadelphia, parts of New Jersey, and New York.

"The Hudson Valley is going to get creamed," he said.

It did. So did parts of the Philadelphia region. A deluge in South Philadelphia that night delayed the Phillies-Cubs game, and hailstones fell on Citizens Bank Park.

The Kansas City situation was more perilous. Imy called the National Weather Service office there to say he was issuing a tornado watch. It would then be up to that office to put out the warnings of imminent danger.

Coded notices appear on storm-center monitors when the locals issue warnings, along with the sound of a cash-register ka-ching. But tornado warnings are accompanied by a trumpet blast.

About 3:30, the trumpet sounded for a point far from Tornado Alley. Measurements showed the air there to be more volatile than on any other day in the last 138 years - in Caribou.

Tornadoes have occurred in every state, and some significant ones have hit the Philadelphia region. In July 1994, a twister killed three people in Limerick. Several strong ones touched down in Philadelphia and Bucks, Camden, Chester, and Montgomery Counties in August 1885, killing six people and injuring 61.

Around that time, the federal government began experimenting with tornado outlooks, but decades went by before it became seriously involved in forecasting.

The storm center set up shop in the early 1950s in Washington, then moved to Kansas City in 1954, and from there to Norman in 2006.

It shares space with the National Weather Service, the university's meteorology department, and the National Severe Storms Laboratory - one of whose researchers, Harold Brooks, was a consultant on the movie Twister.

In a touch of morbid humor, the cafeteria is the movie-inspired Flying Cow Cafe.

On the morning of April 17, Russ Schneider was confident the 2011 tornado season wouldn't get worse than this.

More than 30 twisters had ripped through North Carolina, one of them hitting downtown Raleigh. At the end of the three-day siege, at least 24 were dead.

"I thought to myself the next day that was probably the biggest tornado event of the year," he recalled.

He was emphatically and tragically wrong.

Ten days later, April 27, Carbin looked in disbelief at his daily paper map and the riot of colliding colors over the Southeast.

When he completed it at 10:30 a.m., what he found was "the most volatile environment for tornado development that I had ever seen."

It was an environment that would spawn "supercell" thunderstorms - rotating giants that prowl about 3,000 feet up, setting off almost unimaginable tornadoes. Radar images from the Birmingham, Ala., area showed bright white "debris balls," massive swirls of junk perhaps a half-mile wide, hurled skyward and spun in vicious circles.

The atmosphere was dangerously swollen with water vapor. Gulf of Mexico temperatures were well above normal, brewing warm, moist air transported on south winds. Heavy rain that morning gave way to strong sun that allowed the atmosphere to reclaim the moisture. In other words, a powder keg in the Southeast.

It was the third and worst day of the historic three-day outbreak, with more than 300 twisters reported and 317 dead.

If global warming can be indicted as coconspirator, unusual concentrations of water vapor are compelling evidence.

The world unquestionably has warmed in recent decades, and "a warmer atmosphere is going to hold more moisture," Carbin said. That might explain the rain, but, he cautioned, not necessarily the twisters.

Tornadoes need not just water vapor but also winds blowing in different directions at different levels of the atmosphere. All ingredients have to align.

"You've got a recipe for making lasagna," said Brooks, of the storm laboratory. "If you leave out one of the ingredients, you still have food. But it's not lasagna."

His research focus is the puzzlingly high numbers of deaths this season.

"It's a year I never thought I would see in my career," said Brooks, a 21-year veteran. No year has had two days of 60-plus deaths since 1908, and that was so long ago, he noted, "the Cubs won the World Series!"

Brooks, however, isn't ready to pin it all on global warming.

The Joplin tornado, he said, was extraordinary in that it hit a populated region. Even in the most tornado-prone areas, according to his computations, the odds of even a moderate tornado's touching down at a given point in any one year are about one in 5,000. The odds of violent tornadoes' doing so are four times greater.

As for the April events, he said, the warmer-than-normal gulf was a factor, but so was the lack of cleansing cold fronts that would have repelled the moist air.

In May, the pattern changed, and the first three weeks were pleasantly quiet. Then came Joplin. Two days later, 10 people were killed in the Oklahoma outbreak.

That afternoon, May 24, the two twisters that approached Schneider's Norman subdivision and then the storm center were EF-4s on the Enhanced Fujita scale, with winds up to 200 m.p.h.

The first tornado formed at 5:09 p.m. and faded at 6, moments before it reached Schneider's neighborhood. But the second one was still churning toward the center. It stopped just five miles away.

"Even in those moments, there's no panic," Schneider said. "You're just watching and making the decisions you need to make."

The twisters did, in truth, challenge the forecasters' studied calm.

"We were interested in what was about to transpire," Schneider said. "I mean, we're human."