After several days of wavering, computer weather model guidance is closing in on a solution that will likely bring much colder weather across the entire Pacific Northwest beginning early next week.
Steve Pierce, with Northwest Weather Consultants, says at the present time, snowfall levels will likely fall to very near the valley floor as a cold system from Alaska sweeps across the region on Monday.
In the wake of the frontal passage, temperatures will fall further with cold east (off shore) wind developing especially near the Portland metro area and points east into the Columbia River gorge. Daytime high temperatures will likely struggle to get above freezing most of next week, with overnight lows of 15-25 degrees on the westside of the cascades and 5-10 across most of eastern Washington and Oregon. Modified arctic air will likely continue to spread across the region for the remainder of the week.
There is still uncertainty with regards to how much precipitation will be available once the cold air is in place. Some of the more trusted weather models want to then reinforce the cold air with a disturbance later next week that has the potential to bring a region wide snowfall to all elevations, followed by even colder air behind that system, lasting well into the weekend of December 7th-8th.
There is still plenty of time for adjustments to the current modeling forecasts.