The “atmospheric river” meteorologists are calling for to affect the Pacific Northwest this week isn’t expected to dampen travel plans throughout Douglas County, a National Weather Service official said Tuesday afternoon.
Rain in the Umpqua Valley was forecasted to begin Wednesday afternoon and continue through Saturday, with locations at higher elevations — especially those above 2,800 feet — expected to receive snow accumulation.
Shad Keene, a senior meteorologist with the National Weather Service in Medford, said much of the heavier moisture will likely come north of central Douglas County. Still, the weather service called for up to 4 inches of rain by Friday night.
Flood potential remains minimal except for streams and creeks, though heavier rainfall is expected on the Southern Oregon coast.
“Most of the moisture from the atmospheric river is going to come on the coastline and north of us,” Keene said. “It’s probably going to blow past us and drop some moisture, but it won’t be sitting on top of us like it probably will up north.”
Atmospheric rivers, according to the National Oceanic and Atmospheric Administration, are long, narrow regions in the atmosphere — like rivers in the sky — that transport most of the water vapor outside of the tropics. NOAA said on its website that they carry an amount of water vapor roughly equivalent to the average flow of water at the mouth of the Mississippi River.
The rain helps Douglas County take a step toward rainfall normalcy. Keene said that for the calendar year, Douglas County’s rainfall as of Tuesday afternoon was 90% of its average. But for the water year, which began Oct. 1, approximately 4.35 inches of rain had fallen in Douglas County, which is nearly 36% of the Dec. 17 average of 12.22 inches.
Snowpack is good at Diamond Lake, and a winter weather advisory was in effect until 1 p.m. Wednesday. Forecasts on Tuesday called for up to 9 inches of snow on Wednesday night and from 3 to 7 inches of accumulation on Thursday.
Not far south of Diamond Lake, Crater Lake had seen 7 inches of accumulation in the previous 72 hours as of Tuesday afternoon, according to the weather service. It’s been enough for the park to open ranger-guided snowshoe trips, which are free of charge.
Snowshoes are also provided free of charge, while available. Park entry is $15, but it can be free for active duty and retired military. More information can be found by calling the park at 541-594-3100.