Mountain Weather Forecast

Weather Synopsis for Friday & Friday

The Pacific Northwest will experience very active and stormy weather on Friday and Saturday. Nestled between a high around 140 W off the coast of California and a continental-scale trough over the Canadian Interior, a strong NW jetstream is tracking storms across our region.

Friday's broad, but shallow trough will slide across our area this morning and will move east of the area by the afternoon as the strong jetstream slides gradually northward, enabling a warming trend through the early evening hours. The shortwave has a frontal feature which will likely cross the Washington Cascades during the afternoon hours and the Mt. Hood area during the evening hours. Crest-level winds will be moderate over the Cascades and will generally increase as the front approaches and decrease behind the front, but the front does not bring much cooling until the late evening hours. Moderate snow (and rain at lower elevations) will continue over the Washington Cascades today, becoming lighter and showery by the late afternoon and evening hours. Light to moderate rain and snow will develop at Mt. Hood on Friday morning and will continue through Friday night. Precipitation above pass level should remain snow throughout the storm, but right near pass level at Snoqualmie, rain will mix with snow between 4 PM and 10 PM.

Saturday will feature a deepening low pressure with an associated warm front-cold front structure lacking in Friday's system. This storm system will be significantly stronger than Friday's system with significant warm frontal lift combined with NW flow aloft that should be an ideal setup for very significant mountain snowfall. Stormy to very stormy conditions will spread into all areas during the early morning hours on Saturday as the associated surface low pressure slides down the British Columbia coastline, crossing Vancouver Island during the morning hours. The storm will once again feature mostly snow with a brief warm-up, peaking around 11 AM that will bring a potential brief changeover to rain right at Snoqualmie pass and a brief changeover to rain on the lower flanks of Mt. Hood during the late morning and early afternoon hours before a cold frontal passage from 10 AM to 2PM rapidly lowers snow levels. The heaviest snowfall intensities will be during the morning hours as the front approaches, with moderate to heavy snow showers and continued stormy conditions and gradually decreasing winds Saturday afternoon through Saturday night.