Mountain Weather Forecast

Weather Synopsis

Our cool and snowy pattern continues over the short term. A cold upper level trough has set up shop over the PNW.  A new weather disturbance sliding down the backside of the trough tonight will enhance orographic snowfall on Thursday over the west slopes of the Cascades, particularly from the near and south Hwy 2, with the heaviest showers reserved for the West South zone and Mt Hood.  WNW winds will also begin to crank on Thursday and become strong for the same areas with the heavier showers. An atypical take on convergence bands may form as Fraser River Valley outflow winds (N-NE) drive south through the Puget Sound and link up with onshore flow. This could cause localized higher snowfall totals anywhere these bands form Thursday. Temperatures are likely to drop for the north Cascades including the Mt Baker area and Washington Pass during the day as modified arctic air pushes into the region. 

The southward march of cold temperatures will continue into Friday with 5000' temperatures daytime highs near zero in the north and single digits/lower teens for the central and south WA Cascades. Offshore flow and easterly winds will start to crank through the Passes, creating the potential for dangerously low wind chill values.  There will likely be light upslope snow along the east slopes of the Cascades during this period.

If that wasn't enough, a developing offshore storm will pass inland on Friday.  Forecast models are closing in on a consensus but still, there's a fair amount of uncertainty with the storm track. The south WA Cascades and especially Mt Hood are the most likely to receive significant additional snowfall. 

Remember as the temperature drops, so does the snow density. Even some of these lighter precipitation numbers can produce modest snowfall amounts.