An unusually frigid airmass has dropped into the Pacific Northwest and will continue to advance towards the southeast through the weekend into early next week. The closed upper-level low will move onshore tonight across the Pacific Northwest and is already generating snow this morning in the Cascade Mountains.
NAM 500mb Vorticity and Wind Map (Early Sunday Morning)
This low will advance southeastward, then eastward, over the weekend into early next week. This movement will generate snow for the Sierra-Nevada Mountains as well as the northern Rockies. It is possible that Yellowstone National Park and Glacier National Park may see snow by Monday night.
NAM 500mb Vorticity and Wind Map (Early Next Week)
In the Cascade Mountains, 12-20 inches of snow is possible in the higher elevations, but the snow levels may dip to 4,500 feet. The higher elevations of the Sierra-Nevada Mountains may see up to 10 inches of snow, but snow levels may dip to 6,000 feet.
NAM Snowfall Map (Saturday-Tuesday)
It should be noted, this system will generate strong winds in the higher elevations of the western mountains. Some gusts will exceed 70mph. High temperatures will be well below average for this time of the year in the west over the weekend into early next week.
GEFS Temperature Anomaly Map (Saturday-Thursday)
If you have any travel plans out west, please make sure you are aware of the rapidly changing weather conditions that will occur!