Friday, February 8, 2008

Storm Warnings and the Public

The tornado outbreak on Super Tuesday once again brings up the issue of why some people died and why some people don't heed or receive warnings.

As a storm spotter, I am concerned about this issue. I spot storms because I enjoy looking at the storms and trying to analyze what I see. But storm spotting is primarily a public safety effort, so I don't just watch the storms, I report on anything I see that needs to be reported to either help in the warning decision process or to confirm warnings by providing ground truth.

Many times after a major tornado event, TV stations and newspapers will carry a quote from a survivor saying, "We didn't get a warning!"
With all due respect, many people don't get warnings, not because the warning didn't come out, but because they just don't "get" the warning.

Part of the problem is the criteria the National Weather Service uses to define a severe thunderstorm. The thresholds for wind and hail are too low. The NWS considers a storm severe if winds are at least 58 miles per hour, or hail is 3/4 inch in diameter, about the size of a penny. As a result, the NWS issues severe thunderstorm warnings, the warnings get confirmed because a spotter reports wind or hail that matches the criteria, but no damage occurs. The public then becomes accustomed over time to not expecting anything bad to happen. Then later, a thnderstorm drops golfball-sized hail on someone or strong winds knock out power and tears up some stuff, and people are surprised that something bad happened!
The NWS has improved their warnings. They no longer issue warnings that blanket entire counties.except when the entire county is threatened. Now the warnings will cover only the threatened areas, and the text of the message will mention specific cities and towns.

The biggest element in this issue is the public: how they perceive and receive the warnings.
In some places, the public receives no warnings because of in insufficient delivery system. Many areas do not have sirens to alert those who are outside, or in their cars. Some areas have poor TV and radio reception, and some TV and radio stations will not interrupt their regular programming to give out the warning. To solve this, the FCC could require all TV and radio stations relay storm warnings, and people in communities without sirens could seek government grants and such to buy sirens.

A related problem is that many warning messages make a blanket statement that everyone in the warned area should take shelter. When people do, and then they find out later that all that happened was that someone several miles away lost a few shingles, they start to regard warnings as overblown, and then they tend to disregard any warning that comes out. I believe, that unless a storm has a history of producing damage and injury, or the radar clearly indicates strom characteristics that will definitely mean that damage or injury will occur, then messages should state that people should watch their local area and be ready to move to shelter quickly.

The biggest contribution to the solution would be public education. The public needs to be informed about the difference between watches and warnings, the availability or NOAA Weather Radio with SAME (Specific Area Message Encoding) technology, and the just how real the threats of severe weather are.

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