Bomb cyclones trigger atmospheric river aimed at Whatcom
Two “bomb cyclones” that skirted Western Washington blew open the door for what meteorologists call an “atmospheric river” — a series of moisture-laden storms that are on track to drench Whatcom County this week.
Exactly where the heaviest rain will fall remained unclear Tuesday, Oct. 26, said meteorologist Gary Schneider at the National Weather Service in Seattle.
“Wednesday night and Thursday are looking soggy with an atmospheric river aimed at the Pacific Northwest,” Schneider said in the online forecast discussion. “There are still some uncertainties with where exactly the heaviest rains will occur but the general idea is there will be an increased threat of river flooding from this event.”
On Monday, meteorologist Reid Wolcott said the event appears moderate in strength.
Heaviest rain could fall in the south and central Cascades, or it could inundate the North Cascades and British Columbia, he said.
Nevertheless, a hydrologic outlook statement was posted for Wednesday, Oct. 27, through Friday, Oct. 29.
These warm storm systems will keep lowland temperatures in the mid-50s and mountain temperatures above freezing, and precipitation there will fall as rain.
Early estimates from the Northwest River Forecast Center show the Nooksack River rising sharply this week, but cresting Saturday, Oct. 30, at levels below flood stage at measuring stations in Glacier, Nugents Corner and Ferndale.
Small streams could pose a flooding problem, however, said John Gargett, deputy director of the Whatcom County Sheriff’s Office Division of Emergency Management.
“Culverts and drains may also become plugged from all the leaves blown off the trees from the wind over the weekend, plugging them from allowing water to drain and forcing water to collect in lower areas and possibly back up over roads,” he said in an email.
This story was originally published October 26, 2021 at 5:00 AM.
