Storm clouds are gathering in Seattle. A rare heavy snowfall is likely. Dans pic.

La Nina patterns can sometimes bring heavy snow to places that see it rarely. One of those places is the Pacific Northwest, to the west of the Cascades. So far, this winter has been very atypical of a La Nina year and the reasons why are fascinating (and will be the subject of my next post). The pattern is now looking more like what we usually see and it sure looks like Seattle is going to get buried.

Temperatures are below -25C in some areas on the west side of the Canadian rockies! This is a classic set up for snow and ice in Vancouver and Seattle.

To get snow in Seattle, you need to have true Arctic air coming down to the west side of the Cascades, and that is happening right now. A strong Pacific storm will push warm and moist pacific air up over the dome of cold air, and this will set the stage for heavy snowfalls. Higher elevations to the west like Stampede Pass will measure the snowfall in feet and perhaps meters!

You are gong to hear about this one on the network newscasts. The snow will start tonight and fall through much of tomorrow.