The National Oceanic and Atmospheric Administration has forecast the potential for a change in local weather pattern beginning late Saturday, with the possibility of heavy snow in the mountains and light accumulation on the valley floor.

A storm system followed by a cold air mass is expected to move into the region late Saturday night and into Monday. The pattern is expected to produce heavy snow late in the weekend at the Cascade passes and possibly in the Coast Range.

The combination also will result in a potential for the snow level to approach the valley floor Monday and Tuesday, but any snowfall at that time would likely be light.