The National Weather Service follows a three-tiered methodology for issuing winter products utilizing the Ready-Set-Go approach. This includes Outlooks, Watches, and Advisories and Warnings.

Outlook Phase (READY)

The Hazardous Weather Outlook is a text product that will contain information pertaining to potential winter storms that may occur in the later days of the forecast, typically for periods beyond 48 hours.

Watch Phase (SET)

A Winter Storm Watch is issued when the risk of hazardous winter weather has increased significantly, when there is a strong possibility that weather conditions will reach warning criteria, and typically falls in the 12 to 48 hour portion of the forecast. Winter storm watches are issued for snow, blowing snow, ice, sleet, and possible near-blizzard or blizzard conditions.

A Extreme Cold Watch is issued when conditions are favorable for dangerously cold air, with or without wind, are possible.

Warnings and Advisories (GO)

The following advisories and warnings are issued when an event is occurring, is imminent, or has a high probability of occurrence.  Warnings are issued for events that have a substantial impact and pose a significant threat to life and property.  Advisories are issued for less serious events that still pose a hazard or inconvenience, but typically do not pose an immediate threat of death or injury or significant property damage.

Blizzard Warning: Sustained wind or frequent gusts greater than or equal to 35 mph accompanied by falling and/or blowing snow, frequently reducing visibility to less than 1/4 mile for three hours or more.  Note, there is no snowfall amount criteria when issuing a blizzard warning.

Ice Storm Warning:  Significant, potentially life-threatening icing on the ground, trees, power lines, vehicles, streets, and sidewalks. Generally 1/4 inch or more of ice accumulations in 12 hours or less.

Winter Storm Warning: Issued for snow events of 6 inches or more in 12 hours, 8 inches or more of snow in 24 hours, sleet accumulations of 1/2 inch or more, near-blizzard conditions, or any combination of winter precipitation and wind which will produce life threatening conditions. Warnings may be issued for criteria lower than necessary if the combination of all weather phenomena has a high societal impact.

Extreme Cold Warning: When wind chill or actual temperatures values of minus 30 degrees Fahrenheit or colder are expected (previously Wind Chill Warning). Conditions could lead to frostbite or hypothermia. Limit time outside, dress in layers, and cover up exposed skin.
 
Winter Weather Advisory: Typically issued for snowfall of 3 to 5 inches, for sleet accumulations of less than 1/2 inch, for freezing rain of freezing drizzle less than 1/4 inch, for areas of blowing snow reducing visibility, or any a combination of winter precipitation that will produce hazardous, but not necessarily life threatening conditions. Winter weather advisories may be issued for criteria lower than necessary if the event has a high societal impact, such as light snow affecting a morning or evening metro rush hour commute, or for an unusually early or late season event.

Cold Weather Advisory: When wind chill or actual temperature values of minus 20 to minus 29 degrees Fahrenheit are expected. (previously Wind Chill Advisory)

Please note: Snowfall and cold weather criteria differ in NWS offices across the Nation.