The National Weather Service is stumped. Rainfall this 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 has been receiving calls from the public asking about the source of the dirt. One call came from Walla Walla.
Also this morning, Spokane broke a 129-year-old record for Feb. 6 with a high of 55 degrees just after 4 a.m. today. The previous daily record was 54 in 1886.
Turner said today’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 that got into the atmosphere from Mexico.
One of the volcanoes near Colima, Mexico, erupted on Wednesday sending volcanic ash into the sky. Colima is located south of Guadalajara in west central Mexico about 2,600 miles from Spokane.
Today’s wind map showed a strong south to southeasterly flow coming from the direction of Mexico to the Inland Northwest.
Drivers this morning said they could see the dirt in rain drops starting about 9:30 a.m. Storm water 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.
Also, the weather service received a report of a similar event in Albuquerque, N.M., recently, he said.
Bill Morrison, of Spokane, said he lived for years in Alaska and had seen similar-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 this morning for an appointment and discovered a layer of residue on his windshield when 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 visibilities this morning in the Tri-Cities area.
Meanwhile, the weather service said that today’s high in the lower 50s is now 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 has triggered an avalanche warning today for North Idaho.
Mudslides were reported on Friday on state Highway 21 just south of Republic in Ferry County and state Highway 31 at Metaline in Pend Oreille County.
In Spokane, a third of an inch of rain had fallen Thursday night ant early Friday. More rain is expected through the weekend. How much dirt it will contain is up in the air.
More rain is on the way through early Monday. The weather service said the Coeur d’Alene River at Cataldo should crest just below flood stage on Sunday.
The St. Joe River at St. Maries should reach its crest on Tuesday night at a foot below flood stage.
Localized flooding and landslides are possible with the storm.
In addition, North Idaho is under an avalanche warning through midnight.
A flood watch was issued for the North Cascades, Okanogan region, Northeast Washington and North Idaho through Monday afternoon.
Saturday should bring strong gusty winds of 40 to 50 mph out of the southwest, raising the possibility of power outages.
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