A winter storm warning has been posted this afternoon for what’s shaping up to be the biggest snowfall of the season in the Inland Northwest starting this evening and continuing into Tuesday before rain arrives in lower elevations.
The National Weather Service is forecasting 5.5 inches of snow in Spokane and 5.3 inches in Coeur d’Alene through Tuesday.
Forecasters had issued a winter weather advisory earlier today, but upgraded it to a more severe winter storm warning, raising the prospect of a slow and difficult morning commute on Tuesday.
Light snow already has been falling after noon in Spokane, and the main part of the storm should arrive by 7 p.m., said forecaster John Livingston.
The snow should change to a rain and snow mix by midday Tuesday in Spokane as the snow level rises to 2,200 feet in elevation, but precipitation should remain as snow in Coeur d’Alene on Tuesday. Milder air will have reached the area by nightfall Tuesday when rain is forecast in Spokane and Coeur d’Alene. Snow levels are expected to be at 3,000 feet, which is above the elevation of urban areas. Highs should reach the low 30s Tuesday and the middle to upper 30s on Wednesday.
“Snow levels are going to rise,” Livingston said.
Snowfall amounts are expected to be higher in areas north and west of Spokane and lighter to the south. The snow storm should arrive about 4 p.m. today in areas near the Cascades and move eastward into North Idaho by 10 p.m.
Forecasters said they expect 8.8 inches of snow in Sandpoint, 8.6 inches in Colville, 5.2 inches in Pullman, 5.3 inches in Moses Lake and 4.4 inches in Ritzville and 9 inches in Ellensburg.
A strong storm system drawing moisture from subtropical regions of the Pacific Ocean is expected to move onshore later today and run over the top of the remnants of arctic air in place in the Columbia Basin and mountains of the region.
The chance of precipitation tonight and Tuesday is being forecasted at 100 percent.
Until the storm arrives this evening, forecasters are calling for cloudy conditions and 20 percent chance of snow.
Travel across the region could be slowed, particularly along mountain passes.
Milder air will progressively replace the remaining arctic cold so that by Tuesday afternoon the precipitation could be falling as rain in lower elevations. The snow level is pegged at 2,000 feet in elevation in Spokane and Coeur d’Alene, which includes most of the two urban areas outside of downtown Spokane.
Snowfall will be the deepest in mountain areas. Forecasters said that 8 to 15 inches may accumulate above 3,000 feet in elevation in mountainous areas of northeast Washington and North Idaho by Wednesday.
An overnight pulse of snow brought some impressive accumulations to mountains and valleys in North Idaho. A weather spotter near St. Maries reported 4.5 inches of snow over a four-hour period ending at 1:15 a.m. today.
A dusting of new snow fell in Spokane.
Compact snow and ice were reported this morning on Snoqualmie and Stevens passes in Washington. Traction tires were advised. Packed snow was reported on Interstate 90 at Fourth of July Summit and Lookout Pass in Idaho.
At 7 a.m., temperatures had moderated from the single-digit lows of the past week. It was 21 at Spokane International Airport, 24 in downtown Spokane, 16 in Coeur d’Alene, 12 in Deer Park and 31 in Pullman.
The moderating temperatures began Sunday evening following a trace of snow in Spokane. Sunday’s high was 23 degrees just before midnight.
The normal high today in Spokane is 33 and the normal low is 21.
December has been bone dry with Sunday’s trace of snow the only precipitation so far this month. Normally, Spokane would see an inch of precipitation by the middle of December.
Moses Lake on Sunday set a record low of 2 degrees, breaking the mark set in 1955.