With the potential for an ice storm to hit Schuylkill County this week, we wondered, what makes an ice storm a “bad” ice storm?
We all know that ice storms can lead to treacherous travel conditions. But the effects of an ice storm can be even more life-threatening the more that ice continues to accumulate.
Power outages can last for days – or even weeks, sometimes – and tree limbs could break which might lead to property damage.
But how much ice is too much?
SPIA Index
Luckily, there’s a chart to determine just how bad an ice storm can be and what to expect from the ice accumulations under varying circumstances. It’s called the SPIA Index, or Sperry-Plitz Ice Accumulation Index. It was developed by a meteorologist (Steven Piltz) and severe weather response expert (Sidney Sperry) who created this system that assigns a level of severity to ice storms similar to how tornadoes and hurricanes are rated.
The SPIA Index uses a scale of 0-5. And an ice storm gains intensity on this scale based on several factors:
- Ice accumulation
- Temperature
- Wind speed
SPIA Index was developed only back in 2009.
Ice Storm Damage Index
Let’s take a look at how ice storms are rated by the SPIA Index.
Here’s a handy chart Sperry and Piltz developed to help gauge when an ice storm increases in severity:

Image: SPIA-index.com
Photo: License via Depositphotos
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