If you're heading up north from Twin Falls or the Magic Valley... Avalanche Alley is closing again: BOISE COUNTY (KTVB) - The 12-mile stretch of Idaho State Highway 21 between the Grandjean Junction and Banner Summit closed at noon Thursday due to avalanche danger.'Avalanche Alley' has received 13 inches of snow and an inch of water since Wednesday.

The area currently has a 92-inch snow base recorded at Banner Summit.

Avalanche forecasters say warming weather could lead to instability in the snowpack and the possibility of avalanches.