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Winter Storms Ranked Like Tornado F-Scale

NOAA illustration of NOAA winter storm rankings.Jan. 30, 2006 NOAA announced today that for the remainder of the winter season, its scientists will give the public a new, easy-to-understand scale to categorize major snowstorms after they affect the Northeast. The Northeast Snowfall Impact Scale, or NESIS, will quickly calculate the impact of a powerful snowstorm soon after it strikes, and give it a rank, similar to methods used to categorize the strength of tornadoes. (Click NOAA illustration for larger view of NOAA winter storm rankings. Click here for high resolution version. Please credit “NOAA.”)

Until now, NOAA scientists had no way of sizing up a snowstorm's intensity with an index as understandable as the Saffir-Simpson scale for hurricanes, or the Fujita scale for tornadoes. While winds are used to measure hurricane intensity, NESIS will rank the severity of an East Coast snowstorm based on snowfall amount and the population of the affected areas. With NESIS, scientists can quickly assess a snowstorm's impact today, compare it with a storm of the past and assign it one of five categories: Notable, Significant, Major, Crippling or Extreme.

NESIS was jointly developed by Paul Kocin, a winter storm expert at The Weather Channel and Louis Uccellini, director of the NOAA National Centers for Environmental Prediction in Camp Springs, Md. Thomas R. Karl, director of the NOAA National Climatic Data Center in Asheville, N.C., is leading the effort to put NESIS into action, starting with this year's snowstorms.

"The snowfall impact scale is designed to look retrospectively at a recent snowstorm—not to forecast one," said Uccellini, also a noted winter weather expert. "With its rankings, the scale will also give a better perspective on how these major storms affected populations in the Northeast." The snowstorm that moved through Northeast on December 8-9 was a NESIS category 2 (Significant) storm.

NCDC combined a mathematical model that Kocin and Uccellini developed into an automated Geographical Information System that determines the magnitude of each major snowstorm soon after it strikes. NOAA's NCDC, the official archive of U.S. weather and climate records, will be expanding the analysis to review all major storms that have hit the Northeast since the late 1800s.

"NOAA's ability to quickly collect and quality control snowfall observations—as these events unfold—combined with the new NESIS system will help us provide preliminary snowstorm assessments in days instead of weeks," Karl said. He added that NESIS will offer a way to better assess the impact of major snowstorms on the population.

NOAA, an agency of the U.S. Department of Commerce, is dedicated to enhancing economic security and national safety through the prediction and research of weather and climate-related events and providing environmental stewardship of the nation's coastal and marine resources.

Through the emerging Global Earth Observation System of Systems (GEOSS), NOAA is working with its federal partners and nearly 60 countries to develop a global monitoring network that is as integrated as the planet it observes.

Relevant Web Sites
NOAA The Northeast Snowfall Impact Scale (NESIS)

NOAA National Centers for Environmental Prediction

NOAA National Climatic Data Center

NOAA Climate Prediction Center

Media Contact:
John Leslie, NOAA Satellite and Information Service, (301) 457-5005 or Carmeyia Gillis, NOAA Climate Prediction Center, (301) 763-8000 ext. 7163