The cold arctic air that brought record cold temperatures to the region isn’t going to go away without a parting shot.
Partly sunny skies today are going to give way to an advancing plume of precipitation from the Pacific Ocean that is expected to bring a chance of snow and sleet to the Inland Northwest on Tuesday morning.
The National Weather Service this morning posted a hazardous weather outlook for continued cold this morning and the chance of icy precipitation Tuesday. They said ground temperatures are mostly above freezing in the region, so any snow or ice should melt quickly. However, they said there is a chance of ice accumulating on trees, along road bridges and overpasses and in higher elevations.
Highs today should reach the middle 40s before the milder Pacific air begins running over the arctic air on the ground tonight and Tuesday morning.
The overrunning of moist Pacific air sets the stage for frozen precipitation in the morning as it falls through a colder air mass in the lower portions of the atmosphere.
The frigid lows over the weekend are going to go away, but not before another freezing night tonight when a low of 27 is forecast in Spokane.
A record low of 20 degrees was reported on Sunday at Spokane International Airport, breaking the previous record low of 24 set in 2002. A record low of 23 was recorded on Saturday.
The high at the airport on Sunday was 40 degrees, which tied the record for the coldest maximum temperature for the date. The last time it was only 40 degrees on Oct. 11 was in 1881.
In Spokane, the average date of the first measureable snow is Nov. 12, and the first snow of an inch or more is Nov. 19.
The strong ridge of higher air pressure off the Pacific coast is breaking down today. Its north to south air flow that had drawn arctic air into the Inland Northwest and Rockies is switching after more than a week.
The northerly flow will be replaced by a stream of moisture riding on a strong west-to-east jet stream of upper-level air.
But remnants of the arctic cold remain in the lower elevations so that any precipitation on Tuesday falling from higher clouds will potentially reach the ground as snow or sleet in the morning.
The chance of light snow or sleet mixing with rain is about 40 in the morning Tuesday before 11 a.m. Between 11 a.m. and 2 p.m., the precipitation should change to a mix of rain and snow before the cold air is scoured out by the advancing storm and the precipitation turns to all rain by Tuesday night.
Rain is likely through Thursday.
The region could use a good dousing. The last measureable rain in Spokane came on Sept. 17.
The dry weather contributed to a series of dust storms last week, the strongest of which closed Interstate 90 west of Ritzville on Oct. 4.
At 7 a.m., temperatures were consistent in the lower 20s across the region. It was 21 at the airport, 20 at Felts Field, 21 in Coeur d’Alene, 21 at Sandpoint, 20 in Deer Park and 22 in Pullman.
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