The floodwall in Mount Vernon is expected to be overtopped as the river swells. Authorities have told everyone within the river's 100-year floodplain to evacuate.

The NWS says a series of weather systems will bring an estimated 2 to 6 inches of rain to western Washington through Wednesday. Officials say urban and small stream flooding is possible for areas with poor drainage, and saturated soils are at increased risk for landslides and debris flows.