Potentially record-breaking flooding continues to devastate parts of Washington after an atmospheric river pounded parts of the state and Oregon with heavy rain this week.

After three days of heavy rainfall, swaths of Western Washington racked up 12 to 16 inches of rain, according to the National Weather Service (NWS) in Seattle. The skies began to calm on Thursday, Dec. 11, according to NWS, but affected rivers and waterways are still flooded with the excess water dropped by two atmospheric river storms that moved over the region back-to-back.

Also known as "a river in the sky" or "Pineapple Express," atmospheric rivers are long, narrow corridors of concentrated water vapor in the atmosphere that form when warmer air from the tropics moves toward the poles ahead of powerful storm fronts. They work similarly to rivers on the ground but can carry more water over thousands of miles.

As the storm subsides, significant river flooding is expected to continue through the weekend, according to the NWS. Drone footage of the Puyallup River, provided by local police, showed overflow beyond its banks into the city on Wednesday, Dec. 10, while the NWS Seattle warned of 16 river points forecast to reach major flooding on Thursday, Dec. 11.

Authorities have urged residents to monitor official updates, watch for water on roads and “drive carefully” as several flood warnings and watches stay in place across the state. A state of emergency is also still in place, with tens of thousands on evacuation watch.

Photos show the aftermath of the torrential downpour, including cars submerged halfway in flood waters and residents using boats to navigate flooded areas.

See photos of devastating flooding in Washington

Contributing: Reuters, Jeanine Santucci, Julia Gomez, USA TODAY

This article originally appeared on USA TODAY: Photos show devastating flooding in Washington state. See impact.

Reporting by Mary Walrath-Holdridge, USA TODAY / USA TODAY

USA TODAY Network via Reuters Connect