Back-to-Back Pacific Storms to Impact the West Coast; Heavy Snow in the Central Appalachians

Back-to-back powerful Pacific storm systems to impact the Pacific Northwest and northern California through the end of this week with heavy rain, flooding, strong winds, and higher elevation mountain snow. A strong, long-duration atmospheric river will accompany the Pacific storms, bringing excessive rainfall and flash flooding to southwest Oregon and northwest California through the week. Read More >

Have you ever wondered how some of the winter storms you have experienced in your lifetime compare to the most extreme storms in South Dakota history? We have used a special ranking system called the Local Winter Storm Scale (LWSS) to try to do just that. Ranking winter storms is not an easy task, especially when it comes to very old events when modern equipment was not available to accurately measure wind speed, visibility, etc. Because of these data quality limitations, we restricted our analysis to the period 1950-2012. We also know that weather can be highly variable from one location to another. For instance, while Mobridge may have experienced a storm of catastrophic proportions, Watertown may have only experienced light to moderate snow. To account for this variability, we have evaluated the top five worst storms broken out between regions of the NWS Aberdeen forecast area: Mobridge, Pierre, Aberdeen and Watertown.

Here is a brief description of how the Local Winter Storm Scale works to rank a storm:

The Local Winter Storm Scale (LWSS) is a means to rank winter storms in a "semi-objective" fashion using five weather elements frequently found to describe the potential impact (disruption and destruction) of winter storms and blizzards. The five elements are listed below:

Sustained Winds - Travel Disruption
Wind Gust - Damage to Infrastructure
Snowfall - Travel Disruption
Ice - Damage to Infrastructure, Travel Disruption
Visibility - Travel Disruption

The LWSS scale computes a numerical value from 0 (nuisance) to 6 (catastrophic). Also keep in mind that the LWSS does not include several other factors that can be important societal impacts during winter storms including: