DIABLO, Wash. — A portion of state Route 20, also known as the North Cascades Highway, is closing beginning at 6 p.m. Thursday due to avalanche danger.
The roadway will close between mileposts 131 near Diablo and 171 in Okanogan County due to forecasted heavy snow and rain. The Washington State Department of Transportation (WSDOT) will assess reopening that section of the highway next week.
SR 20 is the northernmost route across the Cascade Mountain Range in Washington. It's also part of the Cascade Loop, which is a 400-mile driving tour through the Cascades, according to WSDOT.
WSDOT closes a portion of the highway every year between Diablo and Mazama once snow fills the avalanche chutes that line the highway, which poses a safety risk to travelers and road crews. SR 20 usually reopens in the spring by early May.
A series of weather events are lined up to bring heavy rain, strong winds, and mountain snow to western Washington late this week into the weekend and continuing into early next week.
A cold front accompanied by a "strong" atmospheric river will arrive in western Washington Thursday afternoon and linger throughout Friday, bringing the potential of heavy rainfall.
Snow levels will drop to around 2,500 feet on Thursday evening, bringing snow to the mountain passes, which could contribute to tricky travel conditions on Friday morning. Snow levels will drop to 2,000 feet overnight on Friday.
The Cascades are expected to see heavy rain in this weather system, with 2-3 inches forecasted. The rainfall could cause rivers in the central Cascades to approach the flood stage.
A Flood Watch has been issued for the central Cascades and parts of the southeast Olympics through Saturday afternoon.