Avalanche causes road closure on Idaho 21. Snow, ice shut down other routes
An avalanche trapped motorists and closed a stretch of Idaho 21 as winter weather continued to create difficult driving conditions across the state.
In a news release Thursday night, Idaho Transportation Department officials said an avalanche prompted a 12-mile closure between Grandjean and Banner Summit. That stretch of Idaho 21, about halfway between Lowman and Stanley, is nicknamed “Avalanche Alley” and frequently closes during winter storms.
An initial ITD report said two vehicles were “involved in the avalanche,” though few other details were available. About an hour later, officials said the vehicles’ occupants had been safely escorted from the canyon and were uninjured.
“Last night’s avalanche cycle was driven by a perfect storm of weather,” Bill Nicholson, leader of the ITD avalanche team, said in a news release. “We had very high precipitation intensity, increasing temperature and extremely high winds from the southeast. These are very unusual conditions for this zone.”
ITD will keep Idaho 21 between Grandjean Junction and Banner Summit closed through the weekend as teams work to clear the avalanche.
Weather permitting, ITD’s avalanche team plans to drop explosives along the 11-mile Avalanche Alley stretch to test snowpack behavior and identify any further slides.
Once the snowpack is deemed to be stable, a maintenance team will begin cleanup.
An even lengthier closure blocked off Idaho 21 for 24 miles due to deep, drifting snow, according to the Transportation Department’s 511 road condition map. That closure begins 8 miles north of Idaho City and continues to Lowman, where Idaho 21 meets Banks-Lowman Road.
Other roads are closed across Southern Idaho. A 50-mile stretch of U.S. 20 between Mountain Home and Fairfield remained closed Friday due to heavy, drifting snow. Other closures include a portion of U.S. 93 from Jerome to Shoshone and part of Idaho 75 from Shoshone near the junction with U.S. 20. Idaho 46 is closed from the Camas-Gooding county line to the intersection with U.S. 20.
In eastern Idaho, where forecasts are predicting blizzard conditions, multiple sections of highways are closed.
Across the state, snow, wind and cold temperatures have created potentially dangerous driving conditions. Most major routes around the state were categorized as “difficult” or “fair” on the 511 map Friday morning, with road conditions ranging from snow-covered to icy.
Current road conditions can be found online at 511.idaho.gov.
This story was originally published January 12, 2024 at 10:53 AM.
