A fast-moving afternoon storm dumped several inches of snow on Sonora Pass and Highway 108 on Tuesday, impressing Caltrans workers who called it a “Sierra Surprise.”

Automated snow stations showed snow depths near Sonora Pass between Tuesday morning and Wednesday morning increased by 3 inches at Leavitt Lake, elevation 9,560 feet, and 2 inches at Sonora Pass, 9,624 feet, said Eric Kurth, a National Weather Service meteorologist in Sacramento.

Between 1 and 8 p.m. Tuesday, a cold, upper-level, low-pressure system was moving east over the Highway 108 corridor, and as it shifted east through the evening that’s when it exited the high east edges of Tuolumne County and the Central Sierra, Kurth said.

Winds gusted to more than 30 miles per hour during the storm and overnight lows above Kennedy Meadows dropped into the teens and low 20s.

Caltrans District 10 staff posted photos of the snow-globe world the winter storm brought to Highway 108.

They said in their social media post they were surprised by the rapid snow accumulation and they were trying to get the pass open again Wednesday.

"This storm gave us a big surprise,” Caltrans District 10 staff said in their post Wednesday. “Check-out some great photos from our CT Long Barn Supervisor, Chris Baker, taken at dusk last night.”

They said they were only expecting a dusting and ended up with 4 to 5 inches in a very short amount of time.

“By the time our crews got the pass cleared of travelers, they could no longer get to the top of the pass to see total depth,” Caltrans District 10 staff said. “It snowed clear down to Long Barn, with it sticking to the highway from the Sno-Park up. Our safest option for the public was to close the pass for the night.”

Road crews were working hard to get Sonora Pass reopened quickly, Caltrans District 10 staff said.

The storm also temporarily closed Tioga Pass on Highway 120.

As of 3:30 p.m. Wednesday, Sonora Pass and Highway 108 were closed from Kennedy Meadows Road, about 25 miles east of Strawberry, to 8.6 miles west of the junction with U.S. 395 in Mono County. Ebbetts Pass on Highway 4 and Tioga Pass on Highway 120 at the east entrance to Yosemite National Park were both open.

Tuesday’s storm brought the first significant rain and snow of the new water year to the Middle Fork Stanislaus watershed. The new water year started Oct. 1. It’s supposed to be sunny and warm in Mother Lode foothill towns the rest of this week, with Sonora daytime highs in the 80s through Sunday.

Contact Guy McCarthy at gmccarthy@uniondemocrat.com or (209) 588-4585. Follow him on Twitter @GuyMcCarthy.