Monday, December 12, 2016

Snow in Bellingham and the Fraser Outflow

A little bit of a micro climate in Bellingham this morning. I did a quick check of the road conditions by pulling up the WDOT cameras. Just south of Bellingham at the North Lake Samish exit it appears to be snowing but no snow on the ground. The site is the high point on Interstate 5 through the Chuckanut Range between Whatcom and Skagit County and is at about 600 feet elevation. As such it can be an icy spot. But at least at this point it was snow free. 

Just 4 miles to the northwest in Bellingham the ground is covered (3 inches at my office near downtown). The DOT camera at Samish Way is a bit under 200 feet in elevation.

The sharp difference in snow cover is the result of the Fraser outflow. The outflow is not strong enough to get the sub freezing temperatures through the Chuckanut Range and into Skagit County and areas south, at least yet.

The Rocky Mountains block a lot of the cold interior air and the BC Coast Range and Cascades are second line of defense from the cold continental air. Of course it also helps that the general atmospheric air flow is from the ocean. But at times cold air does build up in the interior of northern and central BC. The low spot between western Washington and that pile of cold air is the Fraser Canyon. Western Whatcom County is the first to feel that cold air when this pattern develops.

Arrow point to the Fraser Canyon

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