BURLINGTON — Floodwaters began to recede on Friday after historic inundation in Washington state, but the areas hardest hit by flooding could face another wave of atmospheric river next week, and more inundation is looming.

Heavy rains drenching the Pacific Northwest triggered ‌flooding ​on Thursday across much of the region from Oregon ‌north through Washington state and into British Columbia, closing dozens of roads and prompting the evacuations of tens of thousands of ​people.