20 People Rescued From Flooded R.V. Park in Oregon

Twenty people were rescued from a recreational vehicle park near the Oregon coast after rising creek waters flooded the area on Friday, officials said.

The only bridge in and out of the Neskowin Creek R.V. park along Highway 101, the main north-south route along the Pacific Northwest, was flooded after the creek overflowed following record-breaking rain, Gordon McCraw, the emergency manager for Tillamook County, said.

U.S. Coast Guard crews airlifted 12 people and three dogs from the R.V. park and local agencies evacuated eight other people. About 30 people decided to remain in the park, the Coast Guard said.

All of those rescued were adults and no medical help was needed, according to the Coast Guard, which deployed two helicopters and a rescue swimmer to help the Tillamook County Sheriff’s Office.

Those who opted for an evacuation were taken to a school about 100 miles southwest of Portland, Ore.

Most of Oregon and Western Washington State have had what is known as an atmospheric river cruising through the region since Wednesday evening, causing Oregon’s coast to get an “abnormal” amount of rain, Colby Newman, a meteorologist with the National Weather Service, said on Friday.

Atmospheric rivers are rivers in the sky that move water vapor outside of tropical areas, according to the National Oceanic and Atmospheric Administration. Columns of vapor move with winds, and once the vapor hits a warm front to condense it, rain is created.

Atmospheric rivers differ from conventional storms because there are no strong perpendicular winds to help move rain clouds along. Instead, winds run parallel to the clouds, keeping them sandwiched and stagnant over one area for hours, causing floods because they do not allow the rain clouds to move quickly.

The areas between the coastal communities of Lincoln City and Pacific City, Ore., have had five to 10 inches of rain in the last 48 hours.

The region usually gets at most three to four inches during a heavy rain, Mr. Newman said. This has made the region’s creeks and rivers rise rapidly along the steep coast.

“We have pretty hilly terrain, so water doesn’t get easily soaked in,” Mr. Newman said, adding that the ground was saturated after a rainy fall.

The National Weather Service issued a flood warning for most of Washington and the Oregon coast into Sunday, although perpendicular winds will move the rain south and give flooded areas some respite, Mr. Newman said.