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In Northern Virginia, neighbors were digging out after the storm.
In Northern Virginia, neighbors were digging out after the storm.
Image: StudyHall.Rocks
Workplaces have shut down, and roads are impassable. Snow amasses in slushy pyramids by the roadway. But for all that, is the snow that slammed the East Coast technically a blizzard or simply a snowstorm?

     The National Weather Service describes the storm as bringing "blizzard conditions" from the Middle Atlantic region through southern New England. A blizzard, by definition is “a long severe snowstorm” or “an intensely strong cold wind filled with fine snow,” according to the Webster’s New Collegiate Dictionary.
     The National Weather Service, part of the National Oceanic and Atmospheric Administration, issues a watch for a blizzard or winter storm 24 to 72 hours beforehand if “conditions are favorable” for a storm, according to the weather service website. A "watch" is a kind of head's up notice. Authorities issue a watch so people in the area can make plans to deal with the conditions.
     Here are the conditions the weather service expects when it issues a blizzard watch: “Sustained wind or frequent gusts greater than or equal to 35 mph will accompany falling and/or blowing snow to frequently reduce visibility to less than one-quarter mile for three or more hours.”
     The weather service uses a different metric when issuing a winter storm watch. It defines a winter storm as “heavy sleet, heavy snow, ice storm, heavy snow and blowing snow or a combination.”  More specifically, a winter storm involving snow must have “7 inches or more in 12 hours or less; or 9 inches or more in 24 hours covering at least 50 percent of the zone or encompassing most of the population.”
     Ice is different. A coming ice storm will trigger a watch if the weather service expects one-half an inch or more “over at least 50 percent of the zone or encompassing most of the population.”
     The weather service issues a blizzard or winter storm warning when the hazardous weather is imminent, occurring or highly probable. When the service issues a warning, it means conditions could threaten life or property, the website says. 
     Unlike the situation with hurricanes or tornadoes, it is sometimes difficult to assess the severity of a winter storm. It’s not just how much snow falls but where it falls. “To have a significant statistical weight, a storm must produce 20-30 inches of snow and occur over highly populated areas,” says NOAA’s website.“Since the Midwest is not as densely populated as the [Washington] D.C.- through-Boston corridor, storms that peak in the Northeast will typically have a higher intensity.” 

     To know more:

      National Weather Service: Weather Prediction Center

     NOAA: The worst snowstorms in history

     NOAA-The National Weather Service: Winter Terms

     Related:

     Record-setting temperatures in 2015

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