This is a developing weather story. Please .

Parts of the Pacific Northwest's lower elevations, including the Seattle and Portland, Oregon, metro areas, saw a little snow Monday, and more snow is possible starting Wednesday night.

(INTERACTIVE:|)

Recap of December 5 Northwest Snow

The first system entered the West Coast on Monday morning, causing snow showers to fall around the Seattle metro area. No major accumulations were reported, but some locations saw a dusting. The official measurement at Seattle-Tacoma International Airport was a "trace."

Farther south along Interstate 5, Chehalis, Washington, saw up to 2 inches of snow, while Portland, Oregon, recorded a mixture of rain and snow Monday morning.

Snow levels rose Monday afternoon, so mostly rain showers fell during the second half of the day along Interstate 5, from Seattle to Portland, Oregon. In southwest Oregon, Medford (1,330 feet elevation) picked up 0.3 inches of snow.

A few lower elevations in eastern Washington picked up heavier snow. Ritzville measured 6.5 inches of snow, as of Tuesday morning.

Incidentally, the last measurable snow at Seattle-Tacoma (Sea-Tac) International Airport was over two years ago, a 0.8-inch event on Nov. 29, 2014. For the last one-inch-plus snow event, there, you have to go back to Feb. 8, 2014, when 2.9 inches of snow fell.

On average, Sea-Tac picks up 5.6 inches of snow annually, with measurable (at least 0.1 inches) snow falling four days a year.

MORE ON WEATHER.COM: Seattle Snow

Gordon Jacobson (R) gives a push to Jaloni, 8, and father Tyrell Fincher at the top of a closed snow-covered street on January 18, 2012. (Stephen Brashear/Getty Images)