Snow Eater Wind Comes to Northwest Washington

Down slope winds off of mountain ranges can have a pronounced impact on temperature. Long cold spells in central and eastern Washington will come to abrupt ends when storm systems from the west are strong enough to push across the Cascade Range. The descending air will scour out the pool of cold air but also the descending air warms rapidly causing a sharp jump in temperature. The wind is locally called a Chinook and the term is used widely in the interior northwest U.S. out to Montana and the plains of Alberta.

A similar phenomena took place last night in the lowlands of western Washington - only the wind direction was reversed. A low pressure off the coast to the west created a sharp pressure gradient from east to west across the Cascade Range. The result was a sharp temperature increase from the descending air.         

Bellingham temperature plot

In Bellingham the temperature jumped about 20 degrees in minutes. The temperature spike lasted for a few hours and when the descending winds eased, the temperature returned the low 20s.

A similar effect took place in the Skagit lowlands that I experienced first hand. I had to venture out to pick up Lisa at the train station in Mount Vernon. The wind was very hard from the east; high enough to cause some slipping on the icy roads as the car was pushed about, and formed numerous speed bumps of snow drifts. But on the return the temperature jumped from the low 30s to the mid 50s in less than 5 minutes.

The Blackfeet Indians called these events snow eaters. Indeed much of the snow was eaten away down from its deep layer by the warmish and dry wind before the temperature lowered to the 30s and the slow wet melt that has persisted all day.