The Northwest continues to remain wet and snowy with a train of storms set to slam into the Northwest or Canadian coasts. With the help of an atmospheric river of moisture, heavy snow and rain is expected across portions of the region through Tuesday. An atmospheric river is basically a narrow stream of deep, tropical moisture.
On Saturday to begin the weekend, rain will fall throughout the day along the Washington and Oregon coasts. Showers will also fall in portions of northwestern California, especially in the morning. In terms of snow, heavy snow will fall across the Cascades in the morning, then will likely clear out in the afternoon as that snow moves eastward to eastern Washington and Oregon, much of Idaho, and western Montana and Wyoming. These areas will see the snow falling for a few hours during the day, but we don’t really have an organized storm system to bring a widespread snow.
As the first storm moves into Canada and the atmospheric river cuts off, most of the Northwest will experience a break from the precipitation on Sunday. although portions of Washington will still experience rain showers throughout parts of the day. Some snow showers are also possible in northeastern Washington and portions of Idaho and western Montana.
Now on Monday, a new storm will move into the Canadian coast, and this storm will funnel and steer a new atmospheric river right at Washington. This will aid in heavy rain and snow Monday into Tuesday. Expect a heavy rain along the Washington coast and a few lighter showers on the coast of Oregon. In the mountains, a heavy snow will fall in portions of the Cascades as snow levels fall as the day progresses. It will be too warm for snow in the Oregon Cascades until Tuesday.
Speaking of Tuesday, snow will continue to come down in the Washington Cascades as well as in Oregon now, falling at a light to moderate clip. Light showers will continue along the Northwest coast with rain and snow showers across parts of the interior Northwest.
For the rest of the week, sporadic rain and snow showers are still expected, but no new storms are forecast to move in.
Through Tuesday, the heaviest precipitation is forecast in Washington. The Cascades will receive as much as three feet of snow while in Oregon, up to a foot and a half is possible. In terms of rainfall, up to three or four inches of rain is forecast for western Washington.