Winter weather terminology

 The National Weather Service issues several different types of headlines to inform the public of hazardous winter weather conditions.  Below is the general criteria for each type of headline.

Watch Type Guidline Criteria*
Winter Storm Conditions are favorable for a winter storm to produce conditions which meet or exceed Winter Storm Warning criteria.
 Blizzard  Conditions are favorable for a winter storm to produce conditions which meet or exceed Blizzard Warning criteria.
 Wind Chill  Conditions are favorable for a winter storm to produce conditions which meet or exceed Wind Chill Warning criteria.
 Warning Type  Guideline Criteria*
 Winter Storm  6+ inches of snow in 12 hours or 8+ inches of snow in 24 hours; 1/2 inch or more of sleet.
 Blizzard  Sustained winds or frequent gusts of 35 mph or more with considerable falling/blowing/drifting snow frequently reducing visibility to less than 1/4 mile for three hours or more.
 Ice Storm  Accumulations of 1/4 inch or more of ice.
 Wind Chill  Wind chills of -30 F and below.
Advisory Type  Guideline Criteria*
 Winter Weather

 3-5 inches of snow, snow/wind with < 1/2 mile visibility and considerable blowing and drifting, freezing rain/drizzle < 1/4 inch accumulation when mixed with other precipitation, sleet < 1/2 inch, a mix of precipitation types.

For early and late season events, the snowfall amounts can be lowered to 1-2 inches if travel may be impacted.

Freezing Rain  Freezing rain and/or freezing drizzle with < 1/4 inch of accumulation.
 Wind Chill  Wind chills of -20 F to -29 F.
 

*Precipitation amounts are expected average values for the forecast area of concern

The criteria for a blizzard is very specific as they are relatively rare events.  Occasionally, winter storm warnings are issued containing the wording of blizzard-like conditions.  When this terminology is used in a winter storm warning, it means a strong winter storm but falling short of the blizzard criteria.

 



Return to News Archive

USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.