<P> A snow emergency is the term used to indicate the active response plan when a snow storm severely impacts a city, county or town in the United States or Canada . Schools, universities, government offices, airports and public buildings may close during a snow emergency to prevent injuries during attempted travel; parking restrictions also usually go into effect to allow snowplows to clear the roads and streets effectively . The precise meaning of "snow emergency" varies depending on the issuing municipality . Snow emergencies are a common occurrence during the winter snowfall season in the Northern United States . The general public is alerted to snow emergency status via local broadcast stations, reverse 911 calls, mass text messaging services, public address systems, or lighted signals . </P> <P> Typically, a snow emergency is declared by the mayor or other chief executive official of a jurisdiction . The declaration is usually issued after the winter storm has impacted a city or county . Winter Storm Warnings, Lake Effect Snow Warnings, Blizzard Warnings, and Winter Weather Advisories issued by the National Weather Service are taken into account when declaring a snow emergency . </P>

How much snow to declare state of emergency
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