Pre-Thanksgiving Storm May Bring First Snowflakes of Season to Seattle, Portland

By Brett Rathbun, AccuWeather.com Meteorologist

November 21,2015; 10:11PM,EST

 

 

Following a sunny, dry weekend, rain, snow and cold air will return to the northwestern U.S. early in the new week.
A storm system will dive across the Northwest early in the week with the coldest air of the season and the potential for snow showers in the lower elevations.
The amount of moisture available with this system will be much less than the previous storms this month. The threat for any additional flash flooding with this system will be low.
Regardless, a steady snow will blanket the Cascades. The heaviest snow is expected to fall across the Cascades of Oregon through Tuesday.

Significant snowfall will also occur across the Bitterroot Mountains of Idaho and western Montana through Tuesday.
Much of the precipitation across the lower elevations, including Seattle and Portland, Oregon, will be in the form of rain.
As overnight low temperatures approach or drop below the freezing mark, rain showers could change to or mix with snow showers across the lower elevations. The chance for any major accumulations will be low.
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"Snow in Seattle during late November in not all that unusual," AccuWeather Meteorologist Michael Doll said.
"Between 2 and 3 inches of snow fell in the city on Nov. 22, 2010."
Overnight low temperatures will plunge near or below freezing across the lower elevations for much of the week. The last time Seattle and Portland, Oregon, reached the freezing mark was in early March. Daytime high temperatures across much of the Intermountain West will fail to reach 40 Fahrenheit for a couple of those days.
Anyone traveling after dark will need to use caution as wet roads could start to freeze.
Those traveling for Thanksgiving across the Northwest on Monday and Tuesday should give yourself extra time to reach your destination as roads will be wet or perhaps slippery.

Anyone waiting to travel on Wednesday should see improving conditions across the Pacific Northwest as the storm will set its sights from the northern Rockies into portions of California. Those traveling in the northern Rockies may want to consider leaving before Wednesday before the storm system approaches.

Plowable snow could accumulate across the northern Rockies including Billings, Montana; Casper, Wyoming; and Salt Lake City on Wednesday into Wednesday night.
Those flying for the holiday across the northern Rockies should keep checking your airline for any possible delays or cancellations or consider booking a flight for Monday or early Tuesday.
This storm will continue to chip away at the drought across the Northwest. Due to the heavy rainfall this month, much of western Washington, including Seattle, is just abnormally dry, according to the U.S. Drought Monitor.