An atmospheric river starting on Thanksgiving Day is threatening to once again bring heavy rainfall to the Pacific Northwest, just over a week after floods damaged Washington state, officials from the National Weather Service have warned.
In its Thursday weather bulletin, Forecasters at NWS said “a new Atmospheric River containing rich subtropical Pacific moisture takes aim at the Pacific Northwest this evening.”
“A prolonged stretch of moderate-to-heavy rainfall combined with rapid snowmelt could lead to excess runoff. This may result in quickly rising creeks and streams, making localized flooding a possibility in parts of western Washington. Locally heavy rainfall is also possible in far northwestern Oregon, but the heaviest rainfall totals (1 to 3 inches) are most likely to occur in the Olympics and northern Cascades.”
While the high pressure system building atop the Northwest on Friday will provide some temporary respite from the rainfall, another round of downpours is set to arrive late on Saturday.
“This next Atmospheric River event is expected to produce an additional 1 to 3 inches of rain across the Olympics and northern Cascades beginning Saturday afternoon, with locally higher amounts possible. Given the recent periods of heavy rainfall, flooding and excessive runoff will undoubtedly be a concern once again,” NWS said.
Washington’s Whatcom County officials have said that damages from flooding last week could reach as high as $50 million after rain drenched the county for three days and the Nooksack River surged over its banks Nov. 14, inundating the communities of Everson, Nooksack, and Sumas.
At a briefing Tuesday, officials said that the damages from the recent flooding are estimated at $15 million to $20 million for houses, “tens of millions of dollars” for public infrastructure, and up to $20 million for area business centers, The Bellingham Herald reports.
Meanwhile, damage assessments continued and would be added to losses in multiple other Western Washington counties including Clallam, Grays Harbor, Island, Jefferson, Lewis, and King, which Gov. Jay Inslee on Monday declared as disaster areas.
The severe weather emergency order directs that the plans and procedures to the Washington State Comprehensive Emergency Management Plan be implemented and federal aid be directed towards responding to recovery efforts.
In Canada, the storm system was due to hit some southwest B.C. areas where flood recovery efforts were still under way, with the Fraser Valley expecting up to 2 more inches of rain to fall by Friday morning, the government warned Thursday.
“Freezing levels have risen to near mountain tops, and this may worsen recent flooding and impact vulnerable landscapes and infrastructure. Localized flooding in low-lying areas is possible. Heavy downpours can cause flash floods and water pooling on roads. Don’t approach washouts near rivers, creeks, and culverts,” the government said.
Meanwhile, residents in Southern California are dealing with dry Santa Ana winds, NSW forecasters warned in its Thursday bulletin.
“High Wind Warnings have been posted along the mountain ranges, as well as coastal regions. Widespread wind gusts of 35 to 60 mph are expected with damaging gusts up to 75 mph possible in the mountains and foothills,” forecasters said.
“In addition, dangerously low humidity levels support a hazardous environment for fire weather conditions. Red Flag Warnings and a Critical Risk for hazardous fire weather conditions, issued by the Storm Prediction Center, were issued for much of the Southern California mountains and adjacent foothills,” NSW said. “The Santa Ana wind event this afternoon should wind down to an extent by tonight, but an Elevated Risk for favorable fire weather conditions looks to persist into Black Friday.”