Rating Winter Storms

A new winter-storm warning system patterned after hurricane and tornado alerts may become the nationwide standard if tests this winter in Nebraska and Wyoming prove successful.

The system would warn the public about winter storms based on a 1-5 scale similar to those used for hurricanes and tornadoes. It will be tested in 15 counties through April.

Joe Sullivan, a National Weather Service meteorologist in Cheyenne, Wyoming, devised the test system after a storm in October 1997 pummeled Nebraska and Wyoming with thick snow and gale-force winds for 15 hours.

As the storm raged, the weather service issued a winter storm watch, a snow advisory, a snow and blowing snow advisory, and finally — after hundreds of motorists were stranded on two interstates — a blizzard warning.

"It just really made us look like we didn't know what we were doing," Sullivan said. "We were trying to do it in a black and white way, when really there was a lot of gray in there."

The test system gets away from advisories for things like freezing rain, freezing drizzle, and blowing snow, because they don't reveal how serious conditions are, forecasters said.

Sullivan's severity index classifies winter weather into five categories: minor inconvenience, inconvenience, significant inconvenience, potentially life-threatening, and life-threatening. The first three categories correspond to an advisory, the final two to a warning.

The severity index is expected to make it easier for road clearing crews, ambulance drivers, and others to plan ahead.

The weather service plans to review the system this spring. It could be refined and put through another season of testing, abandoned, or tried elsewhere.

"I don't know what the cutoff is for someone to say something is potentially life-threatening," said Wyoming Emergency Management Agency Director Bob Bezek. "I don't know what the difference is between a category four and a five but a couple of loosely defined terms."

The emergency management director for Scottsbluff County, Nebraska, Sherry Blaha, did not think that would be problem.

"Everybody knows what a category-five tornado is," she said. "You would only assume that category-five winter weather would be pretty severe."

By Mead Gruver