Weather

Scale to rate worst blizzards unveiled

WASHINGTON - The superstorm of 1993 was the most devastating blizzard to strike the Northeast in at least a century, according to a new system that rates the impact of East Coast snowstorms.

The new 1-to-5 rating system, somewhat similar to the scales for hurricanes and tornadoes, was announced Tuesday by winter experts from the National Weather Service and the Weather Channel.

In their study of 70 major Northeastern storms, only two - the storm of March 1993 and the January blizzard of 1996 - fell into the "extreme" category with a 5 rating, reported Paul Kocin, winter weather expert at the Weather Channel, and Louis Uccellini, director of the Weather Service's National Centers for Environmental Prediction.

Their Northeast Snowfall Impact Scale, or NESIS, is being published this week in the Bulletin of the American Meteorological Society.

The ratings are designed to assess the impact of a storm after it is over, the way the Fujita scale is used to rate tornadoes. Kocin said he can foresee a day when it might be possible to develop the blizzard scale for use in warning of coming events the way the Saffir-Simpson scale is used with hurricanes.

But that will require improvements in forecasting snowfall amounts, however, he said. Such forecasts are much more difficult that mere storm tracks, Kocin said.

The new winter storm rating system considers the amount of snow, the size of the area covered and the population residing in that area to estimate the human and economic impact of the storm.

Thus, 30 inches of snow over the Appalachian Mountains would have a lower rating than the same amount over the Washington-Boston corridor, Uccellini explained.

To account for population shifts over time, the researchers analyzed the area and amount of snow for 70 storms, estimating the impact each would have had on the population as of 1999.

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