Image: People look through debris
Brett Deering  /  Getty Images
Shawna Berry and Josh Harris look through the debris of their home in Slaughterville, Okla., on Tuesday after a tornado swept through.
updated 5/11/2010 7:37:01 PM ET 2010-05-11T23:37:01

Days before deadly tornadoes raked the Plains, forecasters warned people that big storms were on the way and that they would be large and powerful. Scientists even predicted almost to the hour when the twisters might strike.

They were almost right on the money.

Technological advances, particularly the use of supercomputers that can crunch vast amounts of atmospheric data, have given meteorologists powerful new tools to warn of oncoming storms long before they strike.

The line of storms may have spawned as many as 19 tornadoes as it marched through central Kansas and into Oklahoma Monday evening, leveling houses, flipping cars and dropping hail as big as softballs. Five people were killed and dozens more injured.

"What is disheartening is to tell people for a week that something is going to happen, get warnings out and still have people lose their lives," said Dick Elder, chief meteorologist with the National Weather Service in Wichita.

On Tuesday, families picked through broken furniture and dented appliances outside their shattered homes. Garbage trucks scooped up mattresses and other debris. More storms were possible Tuesday night.

In the early 1980s, computer models forecast storms two days in advance. But meteorologists still had to rely heavily on radar and storm spotters to confirm the location, size and strength of tornadoes.

"Comparing 20 years ago to today it is different as daylight and dark," Elder said. "We still use spotters to verify what we are seeing, but our warnings are so much more."

Computer models can now forecast threatening storms a week or more in advance — and do so more accurately than ever.

Supercomputers at the National Oceanic and Atmospheric Administration in Camp Springs, Md., provide information that is sent to the Storm Prediction Center in Norman, Okla., and on to National Weather Service field offices, where warnings are issued for local areas.

"Year after year, the precision and the accuracy of those models increases," said Mike Foster, the meteorologist-in-charge at the National Weather Service office in Norman. "What we have to do is build in the minds of people everywhere that there is accuracy in those, and when they hear something seven days out, there is some meaning behind that."

Two people died in Oklahoma City — including a young boy hit by debris in his home and a man whose recreational vehicle overturned on him. Three people died in Cleveland County, south of the city. At least 58 others were hurt, two critically.

'Business as usual' criticized
Despite the advance warning, many people disregarded blaring sirens on Monday as three tornado-producing storms bore down on the Oklahoma City area during evening rush hour. Television station video showed motorists clogging roadways as a tornado formed at Norman.

"That looked to me like people cruising down the road there — business as usual," Foster said.

Video: Chasing dark skies And part of the Oklahoma culture could be to blame. Tornadoes occur frequently here, and with regular TV programming often dumped in favor of storm coverage, forecasters fear people have become desensitized to the seriousness.

"I believe that if we warn too much, the message, even the frenetic message, starts to blend into the white-noise background of life," Foster said.

When a hurricane approaches the coast with several days' notice, residents have plenty of time to evacuate. But it's usually impractical to order large-scale tornado evacuations because twisters occur more frequently, and residents would grow weary of the constant warnings, Foster said.

On Tuesday, Gov. Brad Henry thanked the media for telling Oklahomans that the storms were coming but stressed that it was important for people to pay attention.

"If they tell you there's a storm headed your way, you better listen to them and take shelter," Henry said at truck stop along Interstate 40 near where two people died. His news conference was interrupted by a telephone call from President Obama, who promised the state's application for federal disaster assistance would be addressed "very swiftly."

Shawna Alvarez, 32, said tornadoes typically follow paths away from Little Axe, where one of her relatives died Monday. "That's why nobody here has shelters. It doesn't happen," Alvarez said.

'Beat it home' mentality
Misty Vestal, also related to one of the victims, said extended warnings encourage people to take risks they might not have considered when technology was less advanced.

"I think a lot of people think they can beat it home," Vestal said.

But in Wichita, the early warnings a week earlier put the city's school district on heightened alert. Still, it was not until the local tornado warning was issued late Monday afternoon that officials diverted 50 buses full of students to the closest schools with storm shelters.

Video: Deadly twisters tear through Oklahoma Wichita schools monitor the weather. All schools have weather radios, and students and teachers practice tornado drills regularly.

With a tornado spotted west of town and headed toward the heart of the city, school authorities recalled buses and activated their computerized parental-notification system for the parents of elementary students.

"We knew about it last week as well. We were monitoring the situation. ... We all know Kansas weather can change," Arensman said.

At Wakita, a little Oklahoma town featured in the movie "Twister" about tornado researchers, the local nursing home stood by to move patients in case a storm approached. When a tornado warning was issued, nurses moved all the patients to a hallway.

Said Elder: "We can have the greatest warnings out with a great deal of lead time, but it all comes down to a person making a decision that they are at risk and getting to a shelter."

Copyright 2010 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.

Photos: VORTEX2: The great tornado chase

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  1. VORTEX2 scientist Karen Koshiba watches storms develop inside the Doppler On Wheels 7 radar in New Cordell, Okla., on May 10, 2010. From this mobile workstation, DOW 7 controls its radar aquisition, monitors developing storms and communicates with the rest of the Vortex 2 fleet.

    See more photos from the field. (Ryan McGinnis / Back to slideshow navigation
  2. VORTEX2 Scientists Shawn McQuinn, center, and Tim Marshall, right, place a tornado pod near Oberlin, Kan., while Japanese Public Television station NUUK crews film on May 6, 2010. Tornado Pods measure winds, temperature, and relative humidity, and collect dual video inside tornadoes. The data logger is in an armored waterproof aircraft- style "black box" designed to survive even if the Tornado Pod is destroyed. (Ryan McGinnis / Back to slideshow navigation
  3. A toppled truck rests on debris near badly-damaged homes after a tornado just east of the airport in Seminole, Okla., on Monday, May 10, 2010. VORTEX2 was in the area of the destruction. (Ryan McGinnis / Back to slideshow navigation
  4. Vortex 2 team member Tim Marshall points to an inbound supercell while awaiting orders to deploy tornado probes on Highway 182 south of Woodward, Okla., on May 11, 2010. Tim's mission is to deploy weather instrumentation in the path of a tornado. (Ryan McGinnis / Back to slideshow navigation
  5. Dennis Sherrod prepares to climb aboard as VORTEX2 Lead Scientist Josh Wurman and other scientists collect radar data from a supercell thunderstorm south of Seminole, Okla., on May 10, 2010. (Ryan McGinnis / Back to slideshow navigation
  6. VORTEX2 Scientists Josh Wurman and Karen Koshiba, right, display a tornado pod to a camera crew filming "Storm Chasers" for the Discovery Channel in Hays, Kan., on May 6, 2010.

    See more photos from the field. (Ryan McGinnis / Back to slideshow navigation
  7. VORTEX2 scientists Lou Wicker, from left, Josh Wurman Conrad Ziegler and Don Burgess, plan their day at the American Inn & Suites in Perry, Okla., on May 10, 2010. (Ryan McGinnis / Back to slideshow navigation
  8. A Doppler On Wheels (DOW) radar scans a supercell thunderstorm in southeastern Wyoming on June 5, 2009. This storm made a strong, long-track tornado that was observed by VORTEX2 (Verification of the Origins of Rotation in Tornadoes Experiment 2). To date, it is the most comprehensively-observed tornado ever.

    See more photos from the field. (Ryan McGinnis / Back to slideshow navigation
  9. The Doppler On Wheels 7 radar scans a supercell thunderstorm on June of 2009. The 56-foot high mast houses weather instruments and powerful VHF radios that enable this mission control radar to coordinate 10 other radars in the VORTEX2 fleet and communicate with other scientists. A photogrammetry team stands outside the DOW, documenting the storm visually. (Herb Stein) Back to slideshow navigation
  10. Tim Marshall and Dr. Lindsay Bennet deploy a Tornado Pod in front of a strong, long-track tornado in Wyoming on June 5, 2009. (Ryan McGinnis / Back to slideshow navigation
  11. A convoy of Mobile Mesonets travels down the road in pursuit of a tornadic supercell thunderstorm in Wyoming on June 5, 2009. These vehicles contain weather instruments that measure temperature, humidity, wind and pressure surrounding the tornado, helping scientists understand how and why the tornado formed. Some of the Mobile Mesonets also carry Tornado Pods. (Ryan McGinnis / Back to slideshow navigation
  12. Shown here in its mature stage, the most-studied tornado in history moves across the horizon in Southeastern Wyoming on June 5, 2009. Dozens of VORTEX2 vehicles gathered data using radar, weather instruments and tornado pods.

    Follow msnbc_pictures on twitter. (Rachel Humphrey) Back to slideshow navigation
  13. A VORTEX2 crew deploys a tornado pod in front of a thunderstorm that did not produce a tornado on May 12, 2009. Scientists are collecting data in storms that both do and don't produce tornadoes so that they can better understand why the differences occur. (Gino DeGrandis) Back to slideshow navigation
  14. The most-studied tornado in history enters a late, roping stage over Southeastern Wyoming on June 5, 2009. Scientists' research concludes on June 15, 2010.

    Get updates on VORTEX2. (Matt Ryzdik) Back to slideshow navigation
  15. A Mobile Mesonet and Tornado Pod deployment vehicle gathers data from an approaching tornado in Southeast Wyoming on June 5, 2009. The instruments mounted well above the roof are collecting temperature, humidity and wind data. (Paul Robinson) Back to slideshow navigation
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