Milky rain puzzles region’s weather observers

The National Weather Service is stumped. Rainfall Friday morning contained some kind of milky-colored or light gray dirt.

But where the grit came from is a bit of a mystery, said forecaster Mark Turner.

The weather service in Spokane received calls from as far away as Walla Walla with questions about what made the rain that color.

Also on Friday, Spokane broke a 129-year-old record for Feb. 6, with a high of 57 degrees. The previous daily record was 54, set in 1886.

Turner said Friday’s storm originated in the subtropics of the Pacific Ocean and could have tapped into some kind of dust or volcanic ash as it moved westward. The storm had a strong southerly flow as it arrived.

Forecasters were looking at earlier satellite images to see if they could determine a source, he said. One meteorologist speculated that the dirt was volcanic ash from Mexico.

One of the twin volcanoes near Colima, Mexico, erupted on Wednesday. Colima is south of Guadalajara in west central Mexico, about 2,600 miles from Spokane.

Friday’s wind map showed a strong south to southeasterly flow coming from Mexico toward the Inland Northwest.

Another possibility is that ash from last year’s forest fires to the south got blown into the atmosphere or a volcano in Russia spewed grit skyward into the storm days ago as it moved into the western Pacific, the weather service said.

Drivers Friday morning said they could see the dirt in raindrops starting about 9:30 a.m. Stormwater along the curb had a milky color.

“Obviously, it’s dust from somewhere,” Turner said.

The weather service was looking into having a sample tested by a lab, he said.

Bill Morrison, of Spokane, said he lived for years in Alaska and had seen similarly colored rain caused by volcanoes in that state. “It looks like ash to me,” he said.

Doug Oeser, of Colbert, said he drove to Spokane Friday morning for an appointment and discovered a layer of residue on his windshield when he returned to his vehicle. “I’ve never seen anything like it,” he said. “There’s no sense in going to a car wash.”

The weather service reported reduced visibility Friday morning in the Tri-Cities area. Late in the day, forecasters posted a map of locations where the dirty rain had fallen, including Pendleton, Hermiston, the Tri-Cities, Moses Lake, Pullman, Ritzville, Rathdrum, Hayden and Coeur d’Alene.

Meanwhile, the weather service said Friday was the sixth day since Dec. 1 with a high temperature of 50 degrees or greater. The last time that happened was in 1941.

The rain-over-snow event in the mountains triggered an avalanche warning on Friday for North Idaho.

Mud and rock slides were reported on state Highway 21 just south of Republic in Ferry County and state Highway 31 at Metaline in Pend Oreille County. Both of the slides were cleared after several hours.

In Spokane, a third of an inch of rain had fallen Thursday night and early Friday. More rain was expected through the weekend. Localized flooding is possible in urban areas, especially in Coeur d’Alene, the weather service said.

The Coeur d’Alene River at Cataldo should crest just below flood stage Sunday.

The St. Joe River at St. Maries should reach its crest Tuesday night at a foot below flood stage.

More landslides are possible with the storms. A flood watch was issued for the North Cascades, Okanogan region, Northeast Washington and North Idaho through Monday afternoon.

Today is expected to bring strong gusty winds of 40 to 50 mph out of the southwest, raising the possibility of power outages. A high wind advisory was in effect for southeast Washington.

High temperatures through Sunday should be near 50 in Spokane, with lows in the lower 40s.