A flood watch warning was issued by the National Weather Service in Seattle for Tuesday, Dec. 8 through Wednesday, Dec. 9.
King and Pierce counties are among those expected to be affected.
Rainfall is expected to be between 5 and 11 inches in the mountains, and minor to moderate flooding is expected to occur in rivers that run off the Olympics and the west slopes of the Cascades.
The Chehalis River and its tributaries are also expected to be affected.
The large amount of rain that has fallen will lead to an increased threat of landslides due to the extra pressure on soil instability.