Homeland Security and Emergency Services

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Winter Weather Terms

Watches: Be Prepared

  • Winter Storm Watch: Issued for the possibility of severe life-threatening winter weather conditions including: heavy snow, heavy ice and/or near blizzard conditions. Forecasters are typically 50 percent confident that severe winter weather will materialize when a watch is issued.
  • Blizzard Watch: Issued for the possibility of blizzard conditions. Forecasters are typically 50 percent confident that blizzard conditions will materialize when a blizzard watch is issued. There is the potential for heavy falling and/or blowing snow and strong winds.
  • Lake-Effect Snow Watch: Issued for the potential for heavy lake effect snow.
  • Wind Chill Watch: Issued for the potential of wind chills of -25F or less, which can cause rapid frostbite and increase the risk of hypothermia.

Warnings: Take Action

  • Winter Storm Warning: Issued for a combination of heavy snow and/or ice, of which, at least one exceeds or meets warning criteria. Winter weather is expected to cause life-threatening public impact for a combination of winter hazards including heavy snow, ice, near blizzard conditions, blowing and drifting snow and/or dangerous wind chills.
  • Heavy Snow Warning: Issued when 7 inches or more of snow is expected in 12 hours or less, or 9 inches or more is expected in 24 hours or less. Heavy Snow Warnings are issued when there is a high degree of confidence that the entire event will be snow.
  • Ice Storm Warning: Issued for a 1/4 inch or more of ice accumulation which causes damage to power lines and trees. Ice Storm Warnings are issued when there is a high degree of confidence that the entire event is expected to be ice.
  • Blizzard Warning: Issued when blizzard conditions are imminent or expected in the next 12 to 24 hours. Blizzard conditions include sustained or frequent gusts of or above 35 mph AND considerable falling, blowing and drifting of snow reducing visibilities frequently 1/4 mile. Falling and blowing snow with strong winds and poor visibilities are likely, leading to whiteout conditions making travel extremely difficult. Do not travel.
  • Lake-Effect Snow Warning: Issued for 7 inches or more of lake-effect snow. Issued when widespread or localized lake induced snow squalls or heavy showers are expected to produce significant snowfall accumulation. Lake effect snow usually develops in narrow bands and impacts a limited area. These bands can produce very heavy snow with sudden restrictions in visibility. Driving conditions may become hazardous at times.
  • Wind Chill Warning: Issued when the wind chill is expected to be -25F or less. Usually results in a combination of very strong winds and extremely cold air. Frostbite can occur in less than 10 minutes. Avoid going outdoors and wear warm protective clothing if you must venture outside.

Advisories: Be Aware

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  • Winter Weather Advisory: Issued for when hazardous conditions of snow, sleet, ice or a combination of any of these, which neither meets or exceeds warning criteria. Issued for winter weather that will cause significant inconveniences or could be life-threatening if the proper precautions are not taken.
  • Snow Advisory: Issued when an average of 4 to 6 inches of snow is expected in 12 hours or less. Snow advisories are issued when there is a high degree of confidence that the entire event will be snow.
  • Freezing Rain Advisory: Any accumulation of freezing rain that can make roads slippery. Expect a glaze on roads resulting in hazardous travel. Freezing rain advisories will only be issued when there is a high degree of confidence that the entire event will be freezing rain only.
  • Snow and Blowing Snow Advisory: Sustained wind or frequent gusts of 25 to 34 mph accompanied by falling and blowing snow, occasionally reducing visibility to a 1/4 mile or less for three hours or more.
  • Blowing Snow Advisory: Widespread or localized blowing snow reducing visibilities to a 1/4 or less with winds less than 35 mph.
  • Lake-Effect Snow Advisory: Issued for an average of 4 to 6 inches of lake effect snow. Expect lake effect snow showers and assume travel will be difficult in some areas. Some localized snow bands will be intense enough to produce several inches in a few areas with sudden restrictions in visibility.
  • Wind Chill Advisory: Issued for wind chills of -15F to -24F. It is a combination of extremely cold air and strong winds which generate low wind chill readings. If you must venture outdoors, take precautions against frostbite and hypothermia. Frostbite can occur in less than 30 minutes.

Additional Key Terms

  • Snow: Atmospheric water vapor frozen into ice crystals and falling in light white flakes
  • Freezing Rain: Rain that freezes when it hits the ground. It creates a coating of ice on roadways, sidewalks, trees and power lines
  • Sleet: Rain that freezes before it reaches the ground. The precipitation is u in the form of ice pellets.
  • Wind Chill:A measure of how cold people feel due to the combined effect of wind and cold temperatures