Mountain Weather Forecast

Weather Synopsis

There's a mix of low clouds near and west of the Cascade crest and high clouds that thicken as you head further north towards the Canadian border this afternoon. Light and scattered showers have largely ceased while the first radar returns of light warm frontal precipitation can be seen north of the San Juan Islands. Warm frontal moisture and clouds will glance the Olympics, central and northern Cascades with some light snow this evening.  An upper level ridge building offshore will keep the axis of the heaviest moisture well to our north. As the upper level ridge moves inland through Sunday a clearing trend that begins for southern areas tonight will extend to all areas on Sunday.  

While many areas will see mostly sunny skies by Sunday afternoon, there will be quite a mix of freezing levels as cool easterly flow extends up to crest level. Expect temperature inversions that are most pronounced near and along the east side of the Cascades on Sunday. For these areas, above freezing air will punch in above 5000-6000', while lower slopes and valleys stay much colder with a few areas of low clouds trapped below the inversion.

Further west of the Cascade crest and Mt. Hood, you'll still encounter temperature inversions but with relatively milder temps vs the east-side and higher freezing levels. Moderate to strong east winds are likely in the Cascade Passes with moderate S-SE ridgeline winds. 

This temperature and flow pattern will continue until Monday afternoon when a weak N-S oriented front trundles into the region. Precipitation amounts will generally be light, but clouds will increase Sunday night ahead of the front and by Monday afternoon as the front pushes inland, temperature inversions will start to lessen or completely mix out.