A series of storms packing mild, moist air from the subtropical waters of the Pacific has left the Northwest with a leaner-than-normal snowpack.
Lower elevations are seeing day after day of fog between the storms while the upper elevations have basked in more springlike temperatures.
Forecasters said they expect the fog to continue off and on until Sunday, but blow away as another mild storm strikes the region on Sunday.
“We are going to get a fairly quick hosing of some deep subtropical moisture,” forecaster Matt Fugazzi, of the National Weather Service in Spokane, said of the Sunday forecast.
The milder storms dating back to autumn have given the Spokane area a nearly normal amount of precipitation – 6.6 inches of rain or snow water equivalent since Oct. 1. That is about three-quarters of an inch below normal for the period through Monday.
Snowfall is another matter. Spokane has seen only 13.8 inches of snow this season compared with a normal through Monday of 32.4 inches.
The skimpy snowfall is an issue in the mountains where accumulating snowpack has been held down by periodic rainfall and milder temperatures.
Schweitzer Mountain Resort near Sandpoint on Tuesday was reporting just 16 inches of snow near the village with a temperature of 43 degrees under mostly sunny skies.
The Cascades of Washington and Oregon are showing the thinnest snowpacks.
According to the U.S. Natural Resources Conservation Service, snowpack amounts ranged from 17 to 68 percent of normal in the Cascades through Monday. The mountains of northeast Washington and North Idaho are better – the snowpack is running from 65 to 70 percent of normal.
The measurements are based on the water content in the snow.
At the same time, the U.S. Drought Monitor said the important Columbia Basin growing area continues to be in moderate to severe drought although winter rains have provided a slight improvement to the situation there.
Fugazzi said the milder storms are efficient at melting lower-elevation snow, providing a source of moisture to the lower atmosphere.
The storms have brought behind them mild areas of strong high pressure with clear skies aloft. At lower elevations east of the Cascades, cold nighttime air gets held close to the ground under a dome of milder air pushing down from above.
A weather balloon released at 4 a.m. Monday found that the air was near freezing at the ground at the weather service office near Airway Heights. As the balloon rose into the sky, it measured a temperature of 55 degrees at 2,200 feet above ground.
So far this year, 14 days have had fog thick enough to limit visibility to a quarter mile or less. December had 10 such days as measured at Spokane International Airport. That’s on par with the last two years.
That compares with 29 days with low visibility in December and January a year ago and 21 such days in the same two months two years ago.
Looking ahead, Fugazzi said it is difficult to predict whether the region will see more of the same or a return to more wintry weather.
Above-normal temperatures and near-normal precipitation are expected through Feb. 8, according to the U.S. Climate Prediction Center.
“There is still hope,” Fugazzi said. “I’d like to see a healthy snowpack in the mountains.”
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