Rivers in the sky drench the Pacific Northwest

Two storms hit this weekend

Two atmospheric rivers will pound Oregon and Washington back-to-back on Friday and Saturday. Two others already dropped multiple inches of rain earlier this week.

What is an atmospheric river?

An atmospheric river is a narrow band of water vapor pushed by wind. These rivers can be up to two thousand miles long and six hundred miles wide.

“It's literally a river in the sky.”

Compounding impacts bring serious risks

Josh Weiss, a meteorologist with the National Oceanic and Atmospheric Administration's Weather Prediction Center, says multiple atmospheric rivers cause flash flooding, urban flooding and landslides.

“What's really problematic is when you get compounding impacts from multiple atmospheric rivers.”

Ninety percent of Western flood damage

According to forty years of Federal Emergency Management Agency data, ninety percent or more of all flood damage in the Western U.S. comes from atmospheric rivers.

Dangerous timing with king tides

Atmospheric rivers are hitting as El Niño's warm ocean waters raise sea levels and fuel storms. They coincide with annual high tides called king tides, leaving coastal areas at flood risk.

Significant swells expected

Jeff Michalski, a meteorologist at the National Weather Service in Seattle, said Washington's coast could be hit by significant twenty-foot swells this weekend.

El Niño does not strengthen them

F. Martin Ralph, director of the Center for Western Weather and Water Extremes at UC San Diego's Scripps Institution of Oceanography, found atmospheric rivers do not intensify based on El Niño.

“[Atmospheric rivers] don't dance to the tune of El Niño.”