Storm damage surveys: What the National Weather Service does

By Sonya

CHARLESTON, S.C. (WCIV) - Most of the country is heartbroken after hearing about the death and destruction caused by the tornado that ripped through Moore, Okla., Monday afternoon.

Mother Nature still packs a punch that produces deadly tornadoes even through weather forecasting continues to improve.

National Weather Service radars across the country now have the dual-polarization upgrade, which provides meteorologists with even more information during severe weather.

But even the best technology can't keep everyone safe during large and violent tornadoes, which is why some people in Tornado Alley have storm shelters, and hopefully, more will have them in the future.

The Moore, Okla., tornado has a preliminary damage rating of an EF4 and the path length is estimated to be 20 miles. National Weather Service meteorologists from the Norman, Okla., office will survey the damage the next several days.

But what does this surveying process involve?

It's the same for NWS meteorologists across the country, including those that do storm surveys here in the Lowcountry.

"NWS meteorologists closely look at all of the damage produced by the storm to then determine the strength of the winds that produced the damage," said Ron Morales, Warning Coordination Meteorologist with the Charleston National Weather Service Office. "For example, if a well built building was destroyed by wind/tornado, we would use a toolkit that we load on our laptops to give us an idea of how strong the winds had to be to destroy that building. In addition to structures such as buildings, homes, and mobile homes, we can also use this toolkit to estimate wind speeds needed to destroy/damage trees, power poles."

These surveys can be difficult because buildings are often built to different standards, which is why others are involved in rating the damage.

"We also get help from local emergency managers to help survey the damage, especially when there is a lot of damage or multiple storm areas to cover," said Morales. "If it is a big event, with extensive damage and/or fatalities, such as Monday's event in Oklahoma, then usually a national team of people will be deployed to survey the damage. This bigger team will usually include folks from the NWS, private sector, and academia."

The survey team will classify the tornado or wind event on site if possible, but occasionally additional analysis is needed back at the NWS office.

"The preliminary of 'at least EF4' was done mainly based on video and pictures from media," said Frank Alsheimer, Science and Operations Officer with the Charleston National Weather Service. "There was little actual surveying done in the hardest hit areas Monday because they did not want to interfere with search and rescue efforts and there was extreme difficulty in getting to the locations that were hardest hit due to the roads being impassable."

The real surveying will be done Tuesday and Wednesday to determine the exact strength of the deadly tornado.

"The headline-grabbing number is the highest rating for the tornado, but that does not mean it did that type of damage along the entire path length," said Alsheimer. "For instance, while a lot of the damage may be EF3, some of the areas will be EF4, and there may be some smaller areas that received EF5 damage. If that turns out to be the case, the tornado will be labeled EF5 even if it was only a small portion of the entire damage track."

The Norman National Weather Service Forecast Office will have teams conducting surveys of the damaged areas and the results will be available Tuesday or Wednesday.