Avalanche Threat Prompts Closure This Evening Of Idaho 21 In Avalanche Alley


By Paul Johnson

Boise, County, Idaho ( KMVT-TV / KTWT-TV ) - The 12-mile stretch of Idaho 21 between the Grandjean Junction and Banner Summit will close today Friday, Feb. 7 at 6 p.m. as an avalanche-safety precaution, the Idaho Transportation Department announced. The route will be evaluated regularly for a decision on re-opening when conditions improve.
The area received eight inches of snow this morning, and heavy snowfall, higher-density snow, and strong winds are expected in the area through late tonight and tomorrow.
This will be the second closure of Idaho 21 because of the potential for an avalanche. The road was closed most of the weekend of Jan. 10-12 as nine slides tumbled down to the highway.
Despite 45-50 slides each year and more than 250 inches of snow on average, the forecast team has reduced closures by more than 60 percent since they began forecasting slides and slide threats five years ago.
The notorious "Avalanche Alley" section between the Grandjean Junction turnoff and Banner Summit is home to about 60 avalanche chutes and 90 percent of the Idaho avalanches that affect highways.

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