PORTLAND (AP) — The Northern Oregon and South Washington Cascades are under a snow advisory.

The National Weather Service says the advisory remains in effect until 5 p.m.

Cities affected include Government Camp, Detroit, Santiam Pass and Mount St. Helens.

The Weather Service says to expect from 4 to 8 inches of snow Tuesday. As of 1 a.m. Monday, 2 to 6 inches had already fallen. The higher amounts will be at the ski resort levels.

The snow is the result of showers pushing up against the mountain slopes and will decrease Tuesday night and Wednesday as showers diminish in coverage.

Meteorologists urge motorists to be prepared for snow covered roads.