UPDATE, 9:30 a.m. | Traffic continues to be slow throughout the area with multiple accidents.
A collision on I-405 northbound just north of Highway 167 is blocking multiple lanes and slowing traffic.
An earlier stalled semi-truck on northbound Highway 167 near South 180th has cleared, but traffic remains backed up.
ORIGINAL POST | The National Weather Service says the rain falling Thursday in Washington is the first of a series of storms headed for the Northwest over five days.
The downpour has snarled traffic throughout the region for the morning commute, according to tweets from the Department of Transportation.
Travel times out of Everett were reaching triple digits at 7:40 a.m. and alternate routes are recommended.
An accident on eastbound Highway 18 near the Issaquah-Hobart Road has caused a 3-mile backup.
Forecasters say the atmospheric river will hit the region in waves with short lulls in between.
The five-day rain totals are expected to add up to 10 to 13 inches in the Olympics and Cascades and 1 to 4 inches in the western Washington lowlands.
The lulls are expected to allow rivers to carry the runoff without flooding, except perhaps for the Skokomish River, which frequently floods.
The Weather Service says above-normal temperatures will push the snow levels in the mountain to as high as 7,000 feet at times.