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Winter Weather Glossary

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Snow & Ice

Have you ever wondered what makes a storm a blizzard? Below you will find definitions of weather related terms. Definitions provided by the National Weather Service.

Blizzard - A blizzard means that the following conditions are expected to prevail for a period of 3 hours or longer: Sustained wind or frequent gusts to 35 miles an hour or greater and considerable falling and/or blowing snow (i.e., reducing the visibility frequently to less than a quarter mile).

Heavy Snow - This generally means... snowfall accumulating to 4" or more in depth in 12 hours or less or snowfall accumulating to 6" or more in depth in 24 hours or less In forecasts, snowfall amounts are expressed as a range of values, i.e., "8 to 12 inches." However, in heavy snow situations where there is considerable uncertainty concerning the range of values, more appropriate phrases are used, such as "...up to 12 inches..." or alternatively "...8 inches or more...".

Ice Storm - An ice storm is used to describe occasions when damaging accumulations of ice are expected during freezing rain situations. Significant accumulations of ice pull down trees and utility lines resulting in loss of power and communication. These accumulations of ice make walking and driving extremely dangerous. Accumulations are called significant when they amount to a quarter inch or more.

Nor\'easter - A strong low pressure system that affects the Mid Atlantic and New England States. It can form over land or over the coastal waters. These winter weather events are notorious for producing heavy snow, rain, and tremendous waves that crash onto Atlantic beaches, often causing beach erosion and structural damage. Wind gusts associated with these storms can exceed hurricane force in intensity. A nor'easter gets its name from the continuously strong northeasterly winds blowing in from the ocean ahead of the storm and over the coastal areas.

Wind Advisory - Sustained winds 25 to 39 mph and/or gusts to 57 mph. Issuance is normally site specific.

Wind Chill - Increased wind speeds accelerate heat loss from exposed skin, and the wind chill is a measure of this effect. No specific rules exist for determining when wind chill becomes dangerous. As a general rule the threshold for potentially dangerous wind chill conditions is about -20 degrees Fahrenheit.

Winter Storm Warning - This announcement is issued by the National Weather Service when a winter storm is producing or is forecast to produce heavy snow or significant ice accumulations. The criteria for this warning can vary from place to place.

Winter Storm Watch - This product is issued by the National Weather Service when there is a potential for heavy snow or significant ice accumulations, usually at least 24 to 36 hours in advance.

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