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<br />Ramsey County | Multi-Jurisdiction Hazard Mitigation Plan 71 <br />3.12.3 EXTENT <br />Winter weather is typically forecasted three to seven days in advance and can lead to the issuance of a <br />winter weather watch, warning, or advisory in a Hazardous Weather Outlook bulletin. There are several <br />types of these notices depending on conditions. Forecast certainty increases as the time for storm onset <br />decreases. <br />3.12.3.1 Winter Weather Watch <br />A watch is issued 24 to 72 hours in advance when there is a 50 to 80% chance of hazardous winter <br />weather meeting warning thresholds. It aims to give enough lead time for people to prepare and take <br />necessary actions. <br />Table 14. Winter Weather Watch Types <br />Watch Type Description <br />Winter Storm Watch Conditions are favorable for a winter storm event (heavy <br />sleet, heavy snow, ice storm, heavy snow and blowing snow <br />or a combination of events) to meet or exceed local winter <br />storm warning criteria in the next 24 to 72 hours. Criteria for <br />snow is 7 inches or more in 12 hours or less; or 9 inches or <br />more in 24 hours covering at least 50 percent of the zone or <br />encompassing most of the population. Use "mid-point" of <br />snowfall range to trigger a watch (i.e. 5 to 8 inches of snow = <br />watch). Criteria for ice is 1/2 inch or more over at least 50 <br />percent of the zone or encompassing most of the <br />population. This includes lake-effect snow. <br />Wind Chill Watch Conditions are favorable for wind chill temperatures to meet <br />or exceed local wind chill warning criteria in the next 24 to <br />72 hours. Wind chill temperatures may reach or exceed - <br />25°F. <br />Source: www.weather.gov <br />3.12.3.2 Winter Weather Warning <br />These products are issued when hazardous winter weather is occurring, imminent, or highly likely (over <br />80% probability). A warning indicates conditions that threaten life or property. <br />Table 15. Winter Weather Warning Types <br />Warning Type Description <br />Blizzard Warning Blizzard event is imminent or expected in the next 12 to 36 <br />hours. Sustained wind or frequent gusts greater than or <br />equal to 35 mph will accompany falling and/or blowing snow <br />to frequently reduce visibility to less than 1/4 mile for three <br />or more hours. <br />Ice Storm Warning An ice storm event is expected to meet or exceed local ice <br />storm warning criteria in the next 12 to 36 hours. Criteria for <br />ice is 1/2 inch or more over at least 50 percent of the zone <br />or encompassing most of the population.