Mountain Weather Forecast

Weather Synopsis for Friday & Sunday

Updated to reflect lower water numbers for Mt. Hood and tweaks to the Synopsis.

We're in the final stages of a mult-day atmospheric river event. An E-W frontal boundary draped across Washington State should bring decreasing generally moderate precipitation to the Cascades West slopes and Passes should gradually decrease during the day as a perturbation moves east of the Cascades. Alpine winds should be strong to very strong to the south of the frontal boundary, particularly in the Mt. Hood, S. Washington Cascades, and E slopes of the Cascades. The frontal boundary separates the warmer and cooler air with this system. Snow-levels should stay relatively steady today around 3500 ft for the northern Washington Cascades, 4000-45000 ft for the Central Washington Cascades, 5000 ft for the southern Washington Cascades, and 5500-6000 ft for Mt. Hood. 

A low tracking towards Vancouver Island brings a cold front onshore late in the day, spreading increasing rain, snow, and wind into the Olympics and perhaps the Mt. Baker areas as precipitation should generally be light in other areas by that time. 

Friday evening, a sharp cold front passes with strong crest-level winds peaking. Expect moderate to heavy precipitation and snow levels lowering to 3000 ft or lower from 10 PM onwards. Many areas of the west slopes of the Cascades should pick up 10-20 inches of snowfall above 3000 ft with moderate to strong W winds behind the front creating strong orographic through Saturday morning. The low-pressure center reaches the US-Canadian border early in the day with the upper trough digging in during the day on Saturday. The flow switches gradually more northerly Saturday afternoon, gradually shutting off the snow shower activity.