Fresh powder on the way this weekend for the Pacific NW
Saturday, February 17, 2018, 14:39 - After a bit of a break to end the week, unsettled weather moves back into the Pacific Northwest for the weekend, with the potential for more than 3 feet of snow through the Cascades and northern Rockies by Sunday.
All that fresh powder comes with some strong winds and avalanche risk, however, along with tricky driving through passes and the risk for some lower elevation snow as Arctic air sinks into the region. And on the heels of this system, we're expecting some of the coldest air of this winter season to invade from the north, which may be good news for those hoping for the snow to stick around, but not as great for anyone ready for spring.
We take a look at your forecast details, below.
- Strong low pressure system sinks down coast into northwest Washington through Saturday morning, bringing new round of heavy valley rain, mountain snow
- Up to 2 feet of snow expected for northern Cascades, Olympics through Saturday evening; up to a foot for northern Idaho, Montana Front Range
- Atmospheric energy infusion on Sunday means snow and rain persist, staying intense and sinking further south through day
- Total snow accumulations expected to approach 4 feet for parts of northern Cascades, 3 feet central, 2 feet southern; 3 feet for northern Idaho, 2 feet for Front Range
- Cold air coming down from B.C. means snow levels lower through Saturday night/Sunday; should see some snow showers with light accumulations possible down to sea level Sunday
- Coldest air of the season moves in for Monday
Heavy mountain snow
The Pacific storm track remains active as we head into the long weekend with a strong storm system expected to move into the region on Saturday. This system is expected to contain ample Pacific moisture and will bring strong wind into the Pacific Northwest, and a wind advisory is in effect for Saturday. Several strong pulses of atmospheric energy will be the fuel behind this prolonged period of unsettled weather as a trough of low pressure digs down over the Pacific coast through the weekend. These reinforcing shots of energy will keep snowfall intense for the mountains, particularly in the northern Cascades and Olympics, where totals are likely to approach 4 feet by the end of the weekend.
Rainfall in the valleys will be heavy at times, but much of the moisture with this system will be directed straight at the coast out of the west, meaning the rain shadow effect will come into play for much of Puget Sound and the Willamette Valley, keeping rain totals on the lower side. While the valleys will see almost entirely rain through Sunday morning, cold air working its way south as the trough digs deeper will allow for a changeover to snow, north to south, through Sunday morning and early afternoon - a fairly rare event for this later stage of the winter.
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Click play to watch below: Weekend storm track
Coldest air of the winter
Behind this system, we expect to see a push of Arctic air that stands to outdo previous shots of cold the Pacific Northwest has gotten this season. Temperatures are forecast to dip into the mid-20s Sunday and Monday night, with highs rebounding to above freezing - but not that much above - during the day on Monday and Tuesday.
While Wednesday night is expected to see below-freezing low as well, daytime temperatures should start to rebound through mid-week. Long range model guidance suggests that, by the end of February, we should be used to these shots of chilly, Arctic air, however, as large scale troughing in the jet stream is expected to dominate the pattern over the western third of the continent into early March.
With files from meteorologist Ross Giarratana.