An arctic air blast swept south from Canada, spreading into the northern United States. Meanwhile, residents of the Pacific Northwest braced for possible mudslides and levee failures as floodwaters slowly recede.

Washington is prone to intense spells of fall rainfall, but these storms have been exceptional, and more rain is on the way this weekend.

Days of heavy rain due to an atmospheric river that hit Washington state is culminating in the threat of record-breaking deadly flooding in some areas. "This situation is extremely serious," said Washington's Democratic Governor Bob Ferguson on Wednesday. "The next few days are critical."

Washington state is under a state of emergency from a barrage of torrential rain that's sent rivers flowing over their banks, caused mudslides to close highways and trapped people in floodwaters

Washington Gov. Bob Ferguson, who has declared a state of emergency, stressed Thursday that the flooding "is extremely unpredictable" and "potentially historic." "If you have instructions to evacuate from your local authorities, please, please, please evacuate," the governor pleaded.

Gov. Bob Ferguson, who has warned that as many as 100,000 people would need to evacuate statewide, said Friday the Trump administration has approved a disaster declaration.

Washington Gov. Bob Ferguson declared a statewide emergency, estimating that as many as 100,000 residents may soon face evacuation orders.

A foot and a half of rain pushed the water levels of at least four rivers in Washington, including the Skagit River, to hit record highs, surpassing some of their previous records set over 35 years ago.