Mountain Weather Forecast

Weather Synopsis

450pm Update: Adjusted precipitation forecasts for most sites and included a chance of freezing rain Sat night/Sun morning in the discussion. 

It's the calm before another wet and increasingly warm storm plows into our region over the weekend.  High clouds from the developing system will spread inland tonight. Offshore gradients will crank up as well, meaning we can expect breezy easterly winds through the major Cascade gaps.  

This is a weak atmospheric river with copious amounts of moisture but should produce less precipitation than last week's multi-day event. Light snow will move into the Olympics mid-morning and then should begin along the west slopes of the Cascades by late morning and the east slopes of the Cascades closer to mid-day. We can expect snow through Saturday afternoon at most major trailheads but a warming trend will make itself felt on the fringes of our forecast area with snow levels climbing to 3000-4000' for the Olympics and Mt.Hood.  Snowfall rates and S-SE winds will quickly ramp up in the afternoon, piling up several inches of new snow before sunset.

The heaviest precipitation rates and strongest winds should occur Saturday night through Sunday morning as the moisture plume takes aim at the region. Snow levels will push higher Saturday night. Cool easterly flow and cold air along the east slopes of the Cascades will keep snow levels lower, prolonging a switchover to rain at lower/mid elevations until late Saturday night or Sunday morning depending on location. There is a chance for freezing rain for the Passes and for lower elevations along the East slopes of the Cascades during this transition but this does not look like a significant icing event. Most forecast models suggest the central/south WA Cascades and Mt Hood will receive the most precipitation over the weekend. Heavier precipitation should begin to ease off from north to south on Sunday as the moisture tap shifts south into Oregon.