The National Weather Service (NWS) recently introduced the Winter Storms Severity Index (WSSI) — but you may not be familiar with what the graphics are saying.
The official description of the product from the NWS says:
The purpose of the Winter Storm Severity Index (WSSI) is to provide NWS partners and the general public with an indication of the level of winter precipitation (snow and ice) severity and its potential related societal impacts. The WSSI does not depict official warnings, and should always be used in context with official NWS forecasts and warnings.-NWS Website
This product got a solid operational workout in last winter, and I personally felt like it was helpful in focusing on an impacts-based approach to winter weather. With time, it will hopefully end the obsession over 4-8” of snow and if meteorologists were right or not — when the result either way are probably some widespread travel impacts.
Here’s what the scale above is saying:
Winter Weather Area
Expect Winter Weather.
• Winter driving conditions. Drive carefully.
Expect a few inconveniences to daily life.
• Winter driving conditions. Use caution while driving.
Expect disruptions to daily life.
• Hazardous driving conditions. Use extra caution while driving.
• Closures and disruptions to infrastructure may occur.
Expect considerable disruptions to daily life.
• Dangerous or impossible driving conditions. Avoid travel if possible.
• Widespread closures and disruptions to infrastructure may occur.
Expect substantial disruptions to daily life.
• Extremely dangerous or impossible driving conditions. Travel is not advised.
• Extensive and widespread closures and disruptions to infrastructure may occur.
• Life-saving actions may be needed.