NWS unveils Winter Storm Severity Index. What do colors mean?

The National Weather Service this week announced a new color-coded scale to inform people of the possible impact of winter storms and their significance.

Created by the Weather Prediction Center, the Winter Storm Severity Index uses a colored scale to show where severe weather is expected to hit and potential impact.

The index is a tool meant to be used with weather forecasts and not be the sole source of information for a storm, according to the NWS.

The WSSI includes the following scale:

  • White: No impacts.
  • Blue: Limited impacts. Rarely a direct threat to life and property. Typically results in little inconvenience.
  • Yellow: Minor impacts. Rarely a direct threat to life and property. Typically results in an inconvenience to daily life.
  • Orange: Moderate impacts. Often threatening to life and property, some damage unavoidable. Typically results in disruptions to daily life.
  • Red: Major impacts. Extensive property damage likely, life-saving actions needed. Will likely result in major disruptions to daily life.
  • Purple: Extreme impacts. Extensive and widespread severe property damage, life-saving actions will be needed. Results in extreme disruptions to daily life.

The WSSI uses meteorological data and non-meteorological data to forecast the impact of weather. The index is not a forecast for specific events and is not connected to schools closures or other impacts.

The NWS noted that the WSSI only uses forecast information and does not account for previous conditions. During an ongoing storm or incident, the index only represents the current status and not the entire event.

The index was created to help maintain situational awareness and communicate the potential impacts of a winter storm. For more information about the WSSI, click here.

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