Sophisticated Tornado Warning System Saved A Lot Of Lives In Oklahoma

When a devastating tornado touched down in Moore, Oklahoma on May 20, locals had 16 minutes to get to safety before the mile-wide EF4 hit.

Even that seemingly short warning system is enough to save a ton of lives.

The Oklahoma City siren system, a network of 181 emergency warning sirens, was state-of-the-art when it went online in April, 2002. It cost $4.5 million to install the new system, which replaced the cold war-era sirens that covered only the most densely populated parts of the city.

The sirens sound once the National Weather Service issues a tornado warning, and they serve as a signal to turn on a television or radio to get more detailed information about the storm and instructions on how to seek shelter.

The sirens are spread across three counties around Oklahoma City, including the county Moore is located in, according to the city's website. Moore itself has 36 sirens in its Outdoor Warning System, [PDF] many of them near schools:

When the sirens sound, people are advised to seek shelter in a basement or safe room on the lowest level of the building they are in. Avoiding areas near windows and doors are recommended, and people are advised not to travel to shelters during a tornado.

According to ABC News, the elementary schools in Moore don't have underground shelters. Instead, the 4th, 5th, and 6th graders from Plaza Towers Elementary school, which was destroyed by the storm, were evacuated to a local church and reports indicate they are safe.

The third grade class is still unaccounted for.

The National Weather Service in Norman, Oklahoma has a list of sheets for school administrators on how to prepare for a tornado. Students are moved to interior rooms or hallways on the lowest floor, they are kept away from large areas, like gyms, cafeterias, and auditoriums because large room like those have inherently weak roofs.They are told to shelter their heads with blankets, pillows, and mattresses.

Because the Moore schools didn't have underground bunkers, and a direct hit from an EF4 tornado would easily level a building, the school should have an evacuation plan in place.

Oklahoma schools took a close look after Moore elementary schools were destroyed in a tornado in 1999, which luckily struck after kids were home.

A 2000 report by Andrea Dawn Melvin [PPT], of the Oklahoma Climatological Survey, detailed how their safety plans at the time would have resulted in injury.

Students at Eastlake Elementary, in Moore, Oklahoma had been instructed to take refuge in "centrally located offices," which the report states, "none of the identified areas appeared sufficiently constructed to withstand a direct hit by a violent tornado."

In Northmoor Elementary, students shelter in a hallway topped with windows, which have "limited capacity to resist lateral forces" — the exact forces that make tornadoes so dangerous — "obviously, had these corridors been used for shelter during the tornado, numerous injuries or deaths would have occurred."

We don't have data on the specifics of the tornado plans for Plaza Towers or Briarwood Elementary school yet, so we can't be sure how they've changed their tornado safety plans.

All students at Briarwood seem to have been accounted for, but 24 students are presumed dead at Plaza Towers, as police switch from a rescue to a recovery mission. Oklahoma city's chief medical officer says there are at least ten fatalities from the storm.