Snow levels are expected to plunge to as low as 1,500 feet above sea level on Friday as a mix of cold air and precipitation hits the Rogue Valley in the latest December-like storm headed this way.
The National Weather Service has issued a winter storm warning for areas above 2,000 feet and a winter storm watch for lower elevations through 10 p.m. Friday as the front comes in wetter than originally expected.
East Medford developments up the side of Roxy Ann Peak could see an inch of snow, with about 4 to 7 inches above 2,000 feet, weather service meteorologist Sven Nelaimischkies says.
Future fronts are predicted to be warmer and raise snow levels to as high as 6,000 feet, triggering runoff levels that will swell — but likely not flood — area streams parched by what so far has been a very dry winter.
"With the rain falling on the snow, I'd expect you to see a good amount of runoff," Nelaimischkies says.
This series of fronts is finally moving into the Rogue Valley after a high-pressure wall in the Pacific has blocked most storms from hitting the region, diverting them north and east, weather experts say.
That wall moved north this past week, allowing storm systems generating in the tropics to move toward Southern Oregon.
These types of storms, which often start with low snow elevations and then see warm rain falling onto the snow, are more common here in December, Nelaimischkies says.
Up to 2 feet of snow has been forecast for mountain areas during this series of storms, which are the first significant ones to reach Southern Oregon this winter. Most of that snow is forecast for above the 5,000-foot elevation level.
Systems that moved further north today were colder and wetter, dumping as much as 7 inches of snow on the Willamette Valley floor, triggering pileups on Interstate 5, shutting down state offices in Eugene and canceling afternoon meetings at the Oregon Legislature.
National Weather Service forecasters said the storm will be the most widespread snow event in the northern and central Willamette Valley since December 2009.
— Mark Freeman
The Associated Press contributed to this story.