Shaun Tanner has been a meteorologist at Weather Underground since 2004.
By: Shaun Tanner , 6:18 AM GMT on December 17, 2012
This is the Pacific Northwest regional radar. As you can see, a tremendous amount of Pacific moisture from a very strong storm is spreading throughout the Northwest, bringing very heavy rain and high elevation snow from the coast of Washington and Oregon through Idaho. One look at the severe map for the Northwest region shows the true extent of the effects of this storm.
Winter Storm Warnings are the white colors that stretch from northern Washington through the slopes of the Sierra Nevadas in California. In addition, Winter Storm Watches are posted as far east as the Colorado Rockies. I expect these watches to be upgraded to warnings as the moisture and storm moves inland. The WunderMap satellite is showing a ton of moisture streaming inland, which supports the forecasts from the NWS.
A staggering amount of snow is expected areas in the Cascades above a few thousand feet on Monday. The NWS is warming of 2 to 3 feet of snow above 4,000 feet through Monday, with 1 to 2 feet above 2,000 feet. That is a couple feet of new snow in about 24 hours. In addition, wind gusts will reach 60 mph or higher for the Cascades into Monday morning, reducing visibility as the wind blows the freshly-fallen snow. Travelers throughout the Pacific Northwest should be very cautious, especially when traveling over mountain passes.
An important mountain pass in Washington is Snoqualmie Pass, which is likely to see several feet of snow by the time the storm is done.
WSDOT webcam from Snoqualmie Pass. Note the tremendous amount of snow.
Past 2-day snowfall for Draco
We've been watching the atmospheric models over the past several days and have been astounded at the model suggestion of a very active weather pattern for the West Coast over the next two weeks. Of course, long-term forecast over 7 days are extremely unreliable, but the models have been persistent with the opinion of an open storm door through the end of the year. This, of course, includes Christmas.
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