Avalanche threat closed several Idaho highways

Avalanches, or the threat of them, caused a number of closures to Idaho highways in the last few weeks, and also caused at least one death in central Idaho.

The 12-mile, avalanche-prone section of Idaho 21 between Grandjean Junction and Banner Summit – known as Avalanche Alley – closed, reopened, then went through the cycle again in mid-February. During the closures, the area received more than 50 inches of snow and experienced the volatility of rain and melting temps.

In the first round of closures, 35 slides occurred and 21 of those reached the highway. Nine of the 25 slides in the second closure on Idaho 21 reached the roadway; two of the avalanches were large – 40 feet deep and several hundred feet wide each. Tons of timber and debris also reached the highway.

A little farther north, a much longer section of U.S. 12 went through the same close-open cycle twice, but with single-day closures each time. The 61-mile segment from Lowell to Powell was closed, each time due to the threat of slide conditions.

To the east, slide conditions buried a snowmobiling party of four on Sunday (Feb. 16) in Blaine County, killing one. The western U.S. had been relatively quiet on avalanche deaths through early February, but nine people died in slides in the 10-day period ending Feb. 17, bringing the total to 15 deaths nationwide so far this winter season.

Published 2-21-14