Snow level drops to 500 feet in Willamette Valley, SW Wash.

PORTLAND, Ore. - The National Weather Service issued a winter weather advisory for snow from Southwest Washington through the Willamette Valley.

The advisory goes into effect at midnight Tuesday and is expected to last until 11 a.m.

One to three inches of snow is expected in elevations above 500 feet after midnight, the weather service said. Up to one inch of snow could possibly reach the valley floor during the early morning hours.

Snow flurries were widespread Tuesday morning with rain following only at the lowest elevations.

The City of Portland is warning drivers that travel will difficult Tuesday morning, especially in the hills.

The NWS expects around 2 to 4 inches of snow in the Coast Range, Coast Range Foothills and Cascade Foothills. Six to 12 inches are expected in the Cascades.

The Oregon Department of Transportation is warning drivers about slick road conditions near Sylvan on U.S. 26 and on U.S. 26 leading to Mount Hood.

"The higher elevations we're concerned about are Highway 26, Sunset Highway, especially around Sylvan Hill," said Kimberly Dinwiddie with ODOT. "Higher elevations and some of the foot hills surrounding the area highways. They can be tricky tomorrow is the snowstorm really does come."

KATU Meteorologist Rhonda Shelby said the snow level will drop down again Tuesday evening and snow could return overnight.