Winter Storm Advisories

Winter Storm Watch
Issued by local National Weather Service Forecast offices when severe winter conditions including a seven inch or greater snowfall and/or significant icing of 1/2" or more, and/or significant sleet are POSSIBLE within 12 to 36 hours. Winter storm watches are issued for counties and are your first alert to the potential of a major winter storm.

Winter Storm Warning
Issued by local National Weather Service Forecast offices for individual counties when severe winter conditions are EXPECTED. Winter Storm warnings cover snow storms that are expected to drop a seven inch or greater snowfall or a combination of heavy snow, freezing rain and/or sleet that will cause significant disruption to daily activities and travel.

Heavy Snow Watch
Issued by local National Weather Service Forecast offices for individual counties when a pure snow storm producing a seven inch or greater snowfall is POSSIBLE in 12 to 36 hours. (Local criteria)

Heavy Snow Warning
Issued by local National Weather Service Forecast offices for individual counties when a pure snow storm is EXPECTED to produce a seven inch or greater snowfall in a twelve hour time period or a nine inch or greater snowfall in a twenty four hour time period. (Local criteria)

Blizzard Watch
Issued by local National Weather Service Forecast offices for individual counties when a major winter storm producing sustained winds or frequent gusts of 35 mph or greater, considerable falling and/or blowing snow reducing visibility frequently to 1/4 mile or less for a period of three hours or more is POSSIBLE within 12 to 36 hours. . There are no temperature criteria in the definition of a blizzard but freezing temperatures and 35 mph winds will create sub-zero wind chills.

Blizzard Warning
Issued by local National Weather Service Forecast offices for individual counties when a major winter storm producing sustained winds or frequent gusts of 35 mph or greater, considerable falling and/or blowing snow reducing visibility frequently to 1/4 mile or less for a period of three hours or more is IMMINENT or OCCURRING. (Note: there are no temperature criteria in the definition of a blizzard but freezing temperatures and 35 mph winds will create sub-zero wind chills producing particularly severe conditions.)

Freezing Rain/Drizzle Advisory
Issued by local National Weather Service Forecast offices for individual counties when freezing rain or drizzle is expected to occur with ice accretions of less than 1/2". (Only the anticipation of a trace of freezing rain or freezing drizzle is sufficient for the issuance of this advisory as only a slight glazing can cause dangerous travel conditions.)

Ice Storm Warning
Issued by local National Weather Service Forecast offices for individual counties when a significant period of freezing rain is EXPECTED or OCCURRING resulting in ice accretions of 1/2" or greater . Ice storms rank as potentially winter's most destructive and deadly storms resulting in extensive damage to trees and utilities resulting in widespread long duration power outages.

Snow Advisory
Issued by local National Weather Service Forecast offices for individual counties when a light to moderate snow storm is expected to produce a general snow accumulation of 4"-6" in a twelve hour time period. This amount of snow is sufficient to cause an inconvenience to activities and travel.

Winter Weather Advisory
Issued by local National Weather Service Forecast offices for individual counties when a combination of winter precipitation types (snow, sleet and/or freezing rain) are expected to cause significant inconvenience and may be hazardous.

Lake Effect Snow Watch
Issued by local National Weather Service Forecast offices for individual counties when snow induced by cold air flowing over the Great Lakes, accumulating to seven inches or greater, is POSSIBLE within 12 to 24 hours.

Lake Effect Snow Warning
Issued by local National Weather Service Forecast offices for individual counties when snow induced by cold air flowing over the Great Lakes, accumulating to seven inches or greater, is IMMINENT or OCCURRING.