Forecasters say a strong weather system will bring valley rain and mountain snow to western Oregon this week.
The precipitation will begin in earnest on Wednesday and could last three or four days. Amanda Bowen, a meteorologist with the National Weather Service in Portland, said that while December is typically a wet month, “this is a particularly juicy system that’s coming in, so it’s maybe a system that we would see once every few years, instead of maybe once or twice a year.”
Bowen said the Willamette Valley will see nothing but rain. The Cascades passes will see snow at first, changing to all rain by Thursday evening. But she said areas above 6,000 feetshould get plenty of snow. That should help build up the snowpack, which has been well below normal for this time of year.
But she said lower elevation areas, include those around pass levels, may not benefit much in terms of building up snowpack. That's because of the source of this weather system. “It’s originating down in the tropics" she said. That means the warming temperatures arriving with the system will change the snow to rain, and quite literally wash away the snow that fell earlier in the storm.