1/25/2010
Idaho State Highway 21 to close tonight for cautionary measures to prevent avalanche
BOISE - The
section of Idaho 21 from Grandjean Junction to Banner Summit will close at 5 p.m.
tonight (Monday, Jan. 25) as the Idaho Transportation Department Avalanche
Forecast Office takes cautionary measures to prevent avalanches on the open highway.
The "Avalanche Alley" section of Idaho 21 has received 16 inches of
snow with a water equivalent of 1.35 inches over the past few days, making it
ripe for one or more avalanches in the 12-mile section (milepost 93.8 to
105.4). Six more inches of snow are forecast for tonight.
Crews will perform control work and attempt to bring down the avalanches in a
controlled manner tomorrow. If those measures are successful, the road could re-open tomorrow
afternoon.
Tonight
we should receive another six inches of snow," said ITD's Lead Avalanche
Forecaster, Bill Nicholson. "The cumulative weight is getting fairly
high on our weak snow pack. Later this week the temperatures will rise
causing further stress. So we will close tonight and do control work tomorrow
morning."
The
Avalanche Alley area is home to 57 known avalanche slide paths. Ninety-nine
percent of Idaho's avalanches occur between Lowman and Stanley. The
popular recreation route and vital transportation link is closed an average of
60 days per year due to unstable conditions which can lead to avalanches.
During the closure, U.S.12 (Lolo Pass) will be the nearest alternate for
travelers from Salmon, Challis or Montana, and motorists may also choose to go
to Ketchum and take U.S. 20/26 through Fairfield and connect with I-84 at
Mountain Home.
This same stretch of Idaho
21 last closed for two days on New Year's Eve amid avalanche concerns. In that
case about 13 separate avalanches came down on the roadway.