Per the National Weather Service, a storm system approaching from the south will move into the region late Friday night into Saturday morning and bring snow to the Columbia River Gorge and some locations in the Portland-Vancouver metro area. This may, or may not, have the potential for low-elevation snow in Cowlitz County. There is high confidence for accumulating snow in the Columbia River Gorge, but lower confidence for accumulating snow (above 1 inch), in the Portland-Vancouver metro area or Cowlitz County. In Cowlitz County specifically, snow levels are forecast to be about 1,000' Friday night and 1,500' Saturday night.
As the storm system approaches from the south, offshore flow (easterly winds) through the Columbia River Gorge will draw cold air into the northern Willamette Valley and Clark County. The air may be cold enough and deep enough to support snow. In the Portland-Vancouver metro area, the time frame for the potential for low elevation snow to occur will be late Friday night (after midnight) through Saturday morning (Dec 18). Snow is expected in the Columbia River Gorge late Friday night and Saturday. It is uncertain at this point in time how much snow may accumulate in the Portland-Vancouver metro area, if any. If frozen precipitation occurs in the Portland-Vancouver metro area, the precipitation is expected to turn over to all rain by Saturday afternoon. In the Columbia River Gorge and higher elevations, snow will persist through Saturday.
Please prepare for these conditions if your travels take you near the Portland Metro area or the Columbia Gorge. Also, as indicated, higher elevations in Cowlitz County could experience a small accumulation. DEM will monitor this storm and send updates as necessary.