Region Bracing For Blast Of Below-Zero Temperatures

The Inland Northwest’s early winter is about to turn downright brutal.

Lows are expected to plunge below zero on Monday for the second time in a month.

“We are looking for an arctic air mass to drop south out of Canada late Sunday into Monday,” said Lyle Hammer, forecaster for the National Weather Service in Spokane.

Lows of around minus 5 are forecast across northeast Washington and North Idaho on Monday night and Tuesday morning.

Hammer said the arctic cold could ease by midweek, but not without a chance of fresh snow at week’s end.

All of this comes after nearly a foot of snow fell in Spokane during an unusually frigid November.

“This is the beginning of a very old-fashioned cold blustery winter,” said professor Bob Quinn, an expert in long-range weather patterns at Eastern Washington University.

For Quinn, the early winter confirms something he has been saying for two months now.

“We are going to see a much colder-than-normal pattern here through December,” Quinn said.

The Inland Northwest has gotten off easy for the past three years. Winters have been relatively mild, with more rain than normal in the valleys. The coldest it got last winter was 9 degrees.

Experts attribute the mild winters to the combination of El Nino warming and La Nina cooling of the equatorial Pacific.

Both phenomena kept the winter storm track positioned in a west-to-east pattern across the northern temperate latitudes.

Now, water temperatures in the tropical Pacific Ocean are closer to normal.

But there’s still one big abnormality in the central North Pacific, Quinn said.

A pool of warm water south of the Aleutian Islands is causing a strong high pressure ridge to form periodically along the West Coast. That aligns the upper level winds in a north-south pattern, and opens the door for arctic air to drop out of Canada when the northerly flow comes over the Inland Northwest.

The recent cold spells became especially apparent in September, when an early freeze abruptly ended the summer gardening season. A low of 22 degrees killed frost-tender plants and prevented leaves on some trees from turning color and dropping to the ground like they normally do.

On Nov. 11, another arctic outbreak caused the mercury to plunge to minus 2 degrees at Spokane International Airport, the city’s official weather monitoring site. It was the first below-zero reading in two years.

The rest of November was cold, too, with an average temperature of 26.9 degrees, one of the coldest on record.

Looking ahead, Quinn said he expects the worst of the cold to ease by January, but that doesn’t mean winter is going north any time soon.

“This year is totally different,” he said.