STEVENS PASS, Wash. - In what appears to be the first time in at least a decade, snow fell in September at the pass, which has an elevation of 4,061 feet.
The snow arrived in the morning and caught many people off guard.
The Washington State Department of Transportation says around 10 semi-trucks spun out just west of the pass, briefly trapping about 50 cars between them.
"They couldn't get going again and there's only one lane there so everybody behind them was stuck," said WSDOT lead maintenance tech Mike Moreshead.
It happened in a place where summertime slope stabilization work is still going on. Traffic is reduced from four lanes to two.
"There's not much room up there. It bottlenecks pretty quick," Moreshead said.
The snow triggered a traction-tire advisory for drivers, which also brings a prohibition on oversized loads, reducing the risk of a jacknifed semi shutting down the highway.
Requirements for truckers to carry chains begin November 1.
WSDOT's seasonal plow drivers are not yet assigned to Stevens Pass.
The agency keeps one snow plow ready at Stevens Pass year-round, and is now clearing the roadway with three full-time workers staggering their shifts.
While the early snow is unlikely to stay around, managers at Stevens Pass Ski Resort say it helps boost season pass sales.
"We don't see snow in September very much but it's always exciting to see it when we do," said marketing manager Nate Escalona.
He said snow typically begins falling at Stevens Pass in mid-October and starts sticking by Halloween.