Taking a look at the big weather picture first we see a large area of low pressure positioned near the Gulf of Alaska. To the east off the California coastline is a low amplitude ridge of high pressure. Between these two features is the jet stream ushering a substantial plume of moisture toward the BC and Pacific Northwest coast.
A series of waves will move along this jet stream tapping into the abundant Pacific moisture resulting in widespread rain and snow for the Inland Northwest. The forecast trend for this first event has been to reduce the amount of snow…especially along the I-90 corridor and in the Wenatchee Valley. Today and tonight we will see more of a rain/snow mix with not much accumulating snow.
Friday through Saturday Night, the second, stronger storm will move into the region. The precipitable water amount off the Pacific will increase Friday over Northcentral Washington before sagging south Friday night. In the Wenatchee Valley, we could see 1-3 inches of new snow on the ground by Saturday morning. Saturday through Thursday of next week high pressure will arrive which will deliver a drier and colder weather pattern for the start of the new year.