Mountain Weather Forecast

Weather Synopsis

High clouds associated with a frontal band in the NE Pacific will continue to stream over the area this afternoon and night as a frontal system aimed into south/central British Columbia drifts south.  Tonight, cloud cover will be thickest over the Olympics and near the Canadian border and transition to broken skies south of Hwy 2.  The parent low pressure system will dig south of the B.C. coast tonight, and this will orient the frontal boundary into a more SW-NE fashion heading into Sunday. This will also slow the timing of the system a bit. Expect snow to develop over Olympics and northwest Cascades tonight, and become heavy tomorrow afternoon. Snow will develop over the remainder of the region Sunday as well but the heaviest precipitation will hold off until late Sunday afternoon and night. 

Winds will howl out ahead of the frontal boundary late Saturday night and Sunday, with southerly extreme winds forecast by Sunday afternoon for areas west of the Cascade crest.  The cross-Cascade pressure gradient will ramp up tonight through Sunday night, expect strong winds to develop in the major Cascade Passes, which will also keep them quite cold once the heavier precipitation begins. With remarkably cold air over much of the region, snow levels will be tricky, but in general, will rise the most at Mt Hood and to a lesser extent for the Olympics and areas well west of the Cascade crest Sunday through Sunday evening. Freezing rain is possible in the deep valleys of West Central (like Mountain Loop) Sunday afternoon and night. 

The front will sag south Sunday night, pummelling the southern Cascades and Mt Hood. A new frontal wave developing along the old boundary will keep heavy precipitation focused on Mt Hood through Monday. SIgnificant post-frontal snow showers with upper level disturbances rotating inland will pile up additional snow over the Olympics and Washington Cascades on Monday.