Dry October’s end giving way to rain

The golden days and frosty nights of October are as gone as the 10th page on the calendar.

A persistent ridge of high pressure that kept the Inland Northwest sunny and dry for weeks is giving way to rain and maybe even snow in coming days.

“It’s a wet and unsettled forecast,” said Rocco Pelatti, forecaster for the National Weather Service in Spokane.

The cool, rainy weather arrives as daylight-saving time ends – clocks go back one hour at 2 a.m. Sunday – and after nearly a month without any measurable precipitation.

October had slightly more than a quarter inch of rainfall, well below the normal of an inch for the month. It was the driest October since 2002 and the 18th driest on record in Spokane. Together, precipitation in September and October amounted to nearly an inch below normal in Spokane.

The moisture shortage put the Columbia Basin into the abnormally dry category on the U.S. Drought Monitor, managed through the University of Nebraska-Lincoln.

The high pressure pattern also brought cold, still nights. Freezing lows in October were reached on 13 nights at Spokane International Airport, the city’s official reporting station. That compares with an average in October of seven nights of freezing temperatures in Spokane.

A low of 22 degrees in Spokane on Oct. 12 was cold enough to kill the leaves on sensitive trees like catalpas, crab apples, ginkgos and horse chestnuts.

Looking ahead, rain or showers are expected tonight through Monday before a brief drying period Tuesday and Wednesday.

Clearing Tuesday night could cause a cold-air layer to form at the lowest elevations, and snow is possible by Wednesday night at elevations as low as 2,400 feet in areas north of Interstate 90, forecasters said.

A cold-air temperature inversion was evident across the region this week. On Monday morning, the low at Spokane International Airport was in the mid-20s, but at 5,000 feet in elevation the temperature was about 50 degrees. Normally, air is colder aloft.

The inversion, which persisted through the week, caused air pollution levels to rise to the moderate category, leaving a distinct haze over the region. Jon Fox, Weather Service meteorologist, said outdoor burning was allowed in rural locations across the region this week. The forecast for rain and light wind should improve air quality, he said.

The Weather Service’s long-range outlook calls for equal chances of a mild, normal winter or severe, cold season.

Last winter’s near-record snowfall came during a La Niña, a cooling of tropical water in the Pacific Ocean. This fall, ocean waters are normal, giving climate experts no help in making a forecast.

But Fox said the odds of a snowy winter like last year are slim.