By Nic Loyd, WSU meteorologist, and Linda Weiford, WSU News
Blasting into the region on Nov. 19, the freakish combination of freezing rain, wet snow and wind became known as “ice storm ’96.”
If you lived in the Spokane area, that day and the few that followed are likely frozen in your mind. After all, towering trees crashed through houses, power lines snapped and popped and traffic slowed to a trickle on streets glazed with more than a quarter inch of ice.
It was a doozy, all right. The National Weather Service lists it among Washington’s top 25 weather events of the 20th century.
As we witnessed 19 years ago, while accumulating snow can be dangerous, ice from freezing rain can be particularly menacing. All it takes is a thin layer of ice on roads and sidewalks to make driving or walking treacherous. Not only that, but freezing rain is maddeningly hard to predict.
Here’s why: Often times, the precipitation starts out as snow but turns to rain while falling through warmer pockets of air. Then, as the raindrops approach the earth’s surface, they hit a level of cold air.
Now in a super-cooled state, the water droplets freeze on contact with exposed surfaces that include highways, walkways, cars, trees and power lines.
The problem is, it’s hard to know if and when this subtle tango between cold and warm air will occur. All it takes is a rise of a degree or two above freezing and then a drop of a degree or two below freezing as the precipitation falls toward the ground.
How to tell the difference between freezing rain and sleet? Freezing rain falls like normal rain until it hits the ground and freezes to surfaces. With sleet, however, falling rain turns to tiny ice pellets before reaching the ground.
You’ve probably seen these frozen raindrops bouncing off your windshield or the ground. If it was June, then you saw hail. While sleet falls during winter months, hailstones are generally larger and fall during summer.
Several meteorological factors converged to make ice storm ’96 so deadly. First was the fact that there were already several inches of snow covering the ground when the freezing rain struck.
There was also a strong wind that slapped around the ice-encased power lines and trees. Finally, over the next few days, cold temperatures kept the ice from melting.
Spokane, in particular, got clobbered. Two days after Thanksgiving, a spokeswoman for Washington Water Power told the The New York Times: “It’s like the whole city has arthritis.”
Weathercatch is a bi-monthly column published in the Spokesman Review.