Weathercatch: When a storm becomes a blizzard – 13 years ago today

Blizzard warnings issued in the Inland Northwest are rare. But that’s what happened 13 years ago Thursday as a storm system packing strong winds and snow approached our region. And in a case of poor timing, the storm arrived three days after Christmas, one of the busiest travel times of the year.

On Dec. 28, 2010, the National Weather Service in Spokane issued a blizzard warning for the Washington and Idaho Palouse and a winter storm warning for the Spokane area extending into North Idaho.

When is a storm considered a blizzard? Contrary to what many people think, it’s not determined by intense snowfall and bitter cold temperatures, although they often accompany these fierce storms. Instead, a blizzard must contain falling or blowing snow, cold strong winds and low visibility for at least three consecutive hours.

The storm that moved across Eastern Washington 13 years ago walloped the region with blizzard-like conditions, disrupting post-Christmas travel plans and snarling road traffic from Spokane and Coeur d’Alene to Cheney and Moscow, Idaho.

“Widespread accidents, major highway closures and thousands losing power resulted during this major storm,” the National Weather Service Spokane stated on its website.

The storm, which lasted from Dec. 28 through the following day, closed sections of thruways, including Interstate 90 in Spokane and U.S. Highway 95 from Pullman to Moscow. Drifting snow on runways forced the closure of Pullman-Moscow Regional Airport for much of the day on Dec. 29.

Our area is plenty familiar with wintertime snow, but strong winds? Not so much. And when they do blow through, they tend to be too warm to contribute to the formation of blizzards. Also, our abundant trees and rolling hills help shield strong winter winds and blowing snow. By contrast, blizzards in the U.S. are most common across the flat lands of the Great Plains and Upper Midwest where frigid temperatures from Canada clash with powerful jet streams of moving air.

But 13 years ago Thursday, the stage was set for blizzard conditions in the Inland Northwest when an arctic air mass plunged southward and collided with a mass of warm moist air from the Pacific Ocean. The weather change was swift and dramatic. On the afternoon of Dec. 28, Spokane’s temperature reached a mild 40 degrees and light rain was falling. By the close of Dec. 29, 7.1 inches of snow had fallen accompanied by brisk northerly winds. Meanwhile, parts of the Palouse clocked wind gusts reaching 40 mph. Those winds, combined with 5 inches of snowfall in places such as Pullman, produced swirls of blowing snow that drifted over sidewalks and roadways.

Most likely, it will be some time before we see those kinds of conditions again. Arctic air remains far removed from the Pacific Northwest and there’s no sign it will head this way. For now, our weather is largely being dictated by warm Pacific air.

Nic Loyd is a meteorologist in Washington state. Linda Weiford is a writer in Moscow, Idaho, who’s also a weather geek.