Sperry-Piltz Ice Accumulation Index

The SPIA Index is a scale for rating ice storm intensity based on the expected footprint of the storm, the expected ice accumulation as a result of a storm, and the expected damage a storm inflicts on man-made structures, especially exposed overhead utility systems such as power lines. The index was created by Sidney Sperry of the Oklahoma Association of Electric Cooperatives in collaboration with Steven Piltz, a meteorologist at the National Weather Service office in Tulsa, Oklahoma in 2007.

While no one can predict an accurate outage scenario when it comes to ice storms, the Sperry-Piltz Ice Accumulation (SPIA) Index was created to give the utility industry a guide so they can plan accordingly to what the weather forecasts are calling for.