Lots of precipitation, high snowlevels
Avalanche danger might go up to high
Colder air moving in for BC and the Cascades as of Friday
There is a warm atmospheric river of moist, warm air moving in. A river also known as the Pineapple Express. This might cause snowlevels to climb as high as 2500m/8000ft in the Sierra and 2000m/6000ft in the PNW and BC with significant rain below 6,000 feet on Tuesday afternoon. On Wednesday and Thursday, freezing levels should remain around the same altitude and winds will remain moderate or strong in the higher alpine areas. There is currently some uncertainty regarding precipitation amounts for Wednesday and Thursday but it looks like a general cooling trend in the Northwest will bring snow to the bases by the end of the week and moderate amounts to all ski areas. Thursday and especially Friday could be deep at the upper elevations of Mount Rose, Kirkwood, Mammoth, Whistler or Revelstoke. The moisture from the Sierra might moves into the Wasatch and Tetons by the weekend with warm temperatures.
British Columbia and PNW: High avalanche danger
An upcoming storm system is expected to bring 40-70mm of precipitation to BC and the coastal regions. More to the north and east, 5-20 mm is expected. Winds are expected to be strong from the SW and freezing levels will climb as high as 2000m by Tuesday afternoon. On Wednesday and Thursday morning, freezing levels should remain around 2000m and winds will remain moderate or strong in the alpine. We expect freezing levels to drop on Thursday afternoon towards 1500 meters, so Friday will be a powderday in the upper sections of Revelstoke and Whistler.
Sierra: lots of rain and snow
Dry and mild weather will is expected to continue through Wednesday ahead of a major strong storm that will move in by Thursday. Strong SW winds will pick up Wednesday. Thursday we might see heavy rain and snow will be falling, transitioning to snow down to lake level Thursday night. When the cold sector moves in we see snow showers on Friday. Total snowfall will be around 2-4 feet for the mountains above 7000 ft. Since the weekend looks dry, don't wait too long. Friday might be a powder day in Mount Rose, Kirkwood and Mammoth.
Stay stoked, stay tuned