Mountain Weather Forecast

Weather Synopsis

Snow showers are starting to pop up over the mountains this afternoon, driven by daytime heating and a cool unstable air mass overhead. While most showers will be light, we may see locally more moderate showers near the southern volcanoes like Mt Rainier and Mt St Helens. Showers will dissipate overnight and skies will begin to clear in the evening. An upper low dropping south along our coastline will spread some mid and high-level clouds over the Olympics, south Washington Cascades and Mt Hood area later tonight. Clearer conditions will prevail further north.

On Monday, that low pressure system now off the northern Californian coast will deepen and spread increasing high clouds further north. We should see a high overcast in the Mt Hood area, and filtered sunshine for the south Washington Cascades transitioning to mostly skies for the central and especially northern Cascades. There's just enough instability in the north Cascades that we may see an isolated afternoon shower, otherwise we can expect a dry day. The other main story will be increasing E-SE winds over the region. The strongest winds will develop over the Mt Hood area and north to Snoqualmie Pass in the afternoon hours. Afternoon highs will be several degrees warmer on Monday than Sunday.   

On Monday night and Tuesday, light to moderate precipitation from the same system will spread into Mt Hood first on Monday night, and eventually light precipitation in the south Washington Cascades during the day Tuesday. E-SE ridgeline winds will affect all areas during this period and may become extreme for areas like Mt. Hood, Crystal Mt, White Pass and Snoqualmie Pass. On Tuesday, while even the north Cascades should be breezy, they should see more sunshine and warmer temperatures than areas closer to the low and further south.