National Weather Service United States Department of Commerce

Severe Storms Likely This Evening

Severe storms are likely this evening, mainly south of Interstate 90. The main threats with these storms will be damaging winds, heavy rain with localized flooding, and large hail. Read More >


Purpose – The Winter Storm Severity Index (WSSI) has been developed to have a two-fold focus. The first is for use as a tool to assist NWS operational forecasters in maintaining situational awareness of the possible significance of weather-related impacts based upon the current official forecasts. The second is to enhance communication to external partners, media and the general public of the expected severity of potential societal impacts due to expected winter hazards and their distribution.

Audience – The WSSI is intended for operational use by NWS Weather Forecast Offices (WFOs) and Weather Prediction Center (WPC) staff as an enhancement to decision support services, as well as for use and evaluation by NWS partners, the media, and the general public. 

Source – Utilizes NWS forecast information, along with various non-meteorological and climatological data. Updates every 2 hours and because it uses forecast information, will not include recent PAST impacts (i.e. looks ahead, not back).

The index uses a six (6) level impact scale.

days 1-3 overall impacts
Days 1-3 Overall Impacts
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