Mountain Weather Forecast

Weather Synopsis

Showers will continue rotating from the SE to NW over Washington State and from S to N over northern Oregon through this evening. Some heavier showers may contain graupel. Showers are more widespread and relatively heavier near and south of I-90 as an upper level feature rotates inland from the upper trough parked offshore. Organized showers should continue along the east slopes of the Cascades overnight as this feature continues to slide inland, with potentially more moderate snow for portions of the east slopes of the Cascades like the Wenatchee and the Entiat range and lighter amounts further north and closer to the Cascade crest. 

On Thursday, the upper low that's been more or less parked offshore for the last few days will dip south and tap into the stronger southern branch of the jet stream. A new low pressure system will develop offshore on Thursday with warm frontal moisture approaching the Oregon and Washington Coast and likely reaching Mt Hood in the afternoon. While precipitation amounts should be light on Thursday, look for steady light upslope snow that should increase slightly in the afternoon along the east slopes of the Cascades. Offshore flow and easterly winds will also strengthen during the day on Thursday with some areas approaching strong E-SE by the afternoon. 

E-SE winds will further increase Thursday night as the warm frontal precipitation spreads inland. Moderate snow is possible for the south Washington Cascades with potentially heavier snow for the Mt Hood area. On Friday, the occluded front will pass through the area in the morning and be followed by a transition back to shower in westerly flow. This is an unusual storm track for our area and confidence is low in the forecast details.