Why has Bethel been so wet? It’s been swimming in an atmospheric river

Children walk through puddles in Napakiak, Alaska on August 4, 2019 as rain drenched Western Alaska (Photo courtesy of Andrew West)

It’s called an “atmospheric river,” which is what it sounds like: a channel of very moist air coursing across the globe. And it’s what’s been drenching the Yukon-Kuskokwim Delta, but a dry patch is now in sight.

Imagine a cylinder being placed over Bethel that reaches into space. Moving within that cylinder is the second highest amount of water ever recorded in the area.

The rain started on Friday, falling hard and constant through the weekend, then dwindling to a steady mist early in the week. The Lower Kuskokwim River rose two to five feet, and everything is wet. But maybe not for long.

“I would expect the showers to be tapering off, probably by Thursday afternoon, maybe into Thursday evening, generally becoming lighter with time,” said National Weather Service Meteorologist Kaitlyn O’Brien.

Nearly as much rain fell over the weekend as had fallen over the past two months. On Saturday, more rain fell in a single day in Bethel, 1.2 inches, than had ever been recorded for the town.

All that water is funneling up from the tropics. Over the Gulf of Alaska, a high pressure system is spinning clockwise. Over Siberia, a low pressure system is spinning counterclockwise. Together, they’re sucking up warm, moist air from the equator and dumping it over Western Alaska. Meanwhile, that high pressure system has been acting like a barrier, holding the funnel of wet air in place. As of Wednesday, that barrier began breaking down.

“This event was unique in the fact that it was very persistent,” said Gene Petrescu, National Weather Service Regional Scientist.

He says that usually these events pass through in a day or two. This one lasted closer to a week. Also, these events are more common deeper into the fall, rather than in late summer. Even though the rain might be lessening, even more rain could be coming later on.

“We’re now into the season with typhoon developments in the Western Pacific,” Petrescu said. “In fact, there could be a typhoon developing over the weekend, into the next week, out towards Asia.”

And that could push more water over Alaska.

The National Weather Service cautions residents to expect the Kuskokwim River to continue to rise after the rain stops as water flows down from the Alaska Range.