Coldest winter for Seattle in 32 years and more on the way
Friday, March 3, 2017, 10:50 - In what's become a familiar feature of this winter season, the National Weather Service has issued a special weather statement cautioning that another round of snow is on the way for parts of Puget Sound - including Seattle and Tacoma - this weekend.
The statement accompanies winter weather advisories for the Olympics and winter storm warnings for the Cascades, with nearly three feet of snow in the forecast for some higher elevations.
If it seems like we've seen a lot of these kinds of warnings this winter, it's because we have; the 2016-2017 winter season is now the snowiest since 2009, and the coldest since 1985.
The weather service reported 9 inches of new snow Thursday at Mount Baker, with an additional 8 to 18 inches expected through Friday evening. Similar accumulations are forecast for Mount rainier, and White Pass, impacting US Highway 12.
Snow levels are rapidly falling through the day Friday and continuing Friday night as a cold trough digs down from the northwest. Starting out between 2500 and 3500 feet Friday morning, snow levels are forecast to fall to 1500 feet or lower through Friday evening, and dive as low as 500 feet or lower through the lowlands this weekend and Monday.
While the blast of winter weather makes will make for great late-season skiing conditions, drivers attempting to traverse the passes should use caution, especially through Friday and Friday evening, when the bulk of the snow is expected to fall.
Fortunately for lowlands residents, most of the moisture will have passed by the time snow levels dip low enough to allow for accumulations in Puget Sound. That said, snow showers are possible all weekend, and some minimal accumulation is expected - mainly during the morning hours when snow levels are lowest - Saturday through Monday.
Those few inches will add to a snow season already well above average for Seattle, where a little more than 11 inches have been recorded this winter. That makes this the snowiest winter since the 2008-2009 season, and a massive change from last winter, when the SeaTac (where the official measurements are taken) reported no snow at all.
Current Snow-Water Equivalent over the Washington ranges. SWE represents the amount of water that would be obtained by melting all the snow present. Image courtesy National Resources Conservation Service.
Helping the snow along has been the colder-than-usual weather over the Pacific Northwest this winter, with the average temperature running about 3 degrees below normal, and 56 days with below-average highs between December and February.
Part of the thanks - or blame - for this winter can be pinned on La Nina. The southern oscillation was in the La Nina state through January; a phase which tends to favor colder and wetter weather over the Pacific Northwest. But the bulk of the snow fell in one whopper of a storm February 4th and 5th, with a system that tapped moisture from the Pacific north of Hawaii.
The trouble-maker storm, visible on water vapor imagery, shows deep moisture from the central Pacific working its way up the west coast. Image courtesy Unisys.
Unfortunately for winter-weary Northwesters - but good news for people looking to extend their winter outdoor sports season - The Weather Network's official spring forecast calls for continued below average temperatures for the region going into the spring.
As the storm track retreats northward through this transitional season, however, the next three months look to be drier up and down the west coast.