Outdoors blog

Avalanche advisory: snowpack has weak layers

This sunrise view greeted backcountry skiers in the Caribou Lake area of the Idaho Selkirk Mountains on Feb. 3, 2012. (Alison Boggs)
This sunrise view greeted backcountry skiers in the Caribou Lake area of the Idaho Selkirk Mountains on Feb. 3, 2012. (Alison Boggs)

WINTER SPORTS -- Storms helped the region's mountains catch up on precipitation in the past two weeks -- as you can see from powder piled deep in this Selkirk Mountains sunrise photo iPhoned to me this morning by backcountry skier Alison Boggs.

But the snowpack also developed some weak layers, avalanche experts say.

Technicians from the Idaho Panhandle Avalanche Center observed natural avalanches during their Thursday survey and documented some persistent weak layers.

"Falling snow won't be a concern for a while, but the sun and rising temperatures could be," said technician Kevin Davis. "Break out you're spring travel tricks if it's getting too warm or if we get inversions. Those crusts are becoming more of a concern as they continue to break down."

Read on for the full advisory posted this morning, or click here to check out the center's new website under construction.

 

 

AVALANCHE ADVISORY

 

U.S. FOREST SERVICE

FORECASTER: Davis

IDAHO PANHANDLE AVALANCHE CENTER

EFFECTIVE DATE: 02/03/2012

DATE ISSUED: 02/03/2012 0730

OUTLOOK: 02/04-05/2012

This report does not apply to local ski areas within the forecast region and the hazard rating will remain valid through midnight February 3rd, 2012. Special thanks to Idaho Parks and recreation for sponsoring this Avalanche advisory.

Thanks to everyone for sending in pit data this week. Some observations of natural slide activity from earlier in the week across the forecast region and from yesterday on a N aspect in the Selkirks. Check out our new site @ idahopanhandleavalanche.org.

WEATHER

TODAY: Sunny with temperatures in the mountains into the high 20s to the north and low 30s to the south. Light E winds.

TONIGHT: Should be clear tonight, temperatures dropping to low 20s and steady E winds.

SATURDAY: High pressure ridge seems to be parked over the Northwest giving us plenty of sunshine and warmer temperatures well into next week. For the outlook, sunny and warm days with cold and clear nights will create periods of unstable snow, especially above freezing temps on southerly aspects.The avalanche danger will increase if day time temperatures rise above freezing, especially on slopes in direct sun.

Selkirks and Cabinet mountains: We motored about the Cabinets yesterday and found ample powder on all aspects. Snowfall for the week from snotel was about 15 inches of new and in the Selkirks you’ll find from 5 to16 inches, southern Kirks a little deeper. We were in about 2 feet on a N aspect at 6200’ and found a weak layer of surface hoar about 1.5 feet deep that failed with moderate force. On an E aspect we found a moderate weak layer on graupel about 10 inches deep. S aspects are collapsing at the late December ice crust which is rotten. Report of a natural slide off Keokee above the Caribou Hut yesterday. Possibly running on surface hoar layer or a slight crust about 1.5 feet deep. Avalanche danger is rated MODERATE on aspects steeper than 35 degrees above 5,000 feet. Pockets of Considerable avalanche danger may exist especially with above freezing temperatures or direct solar radiation. St. Regis Basin and Silver valley: At Silver Mountain, patrol was getting some easy shears about 1 foot deep in the new snow. In the Basin Carole was finding consistent shears with moderate force on a weak layer over a crust at 2.5 feet deep. 1.5 feet of new snow was firmer at the bottom and seemed to be bonded well. They also noted signs of strong wind-loading. On Moon Pass Ed got hard but clean shears on a crust just over 2 feet deep. All pit observations are confirming that the numerous crusts we have in the pack are decomposing and getting weaker. The forecast weather will break these crusts down further. Avalanche danger is rated MODERATE on aspects steeper than 35 degrees above 5,000 feet. Pockets of Considerable avalanche danger may exist especially with above freezing temperatures or direct solar radiation. Natural avalanches have been occurring for the past couple weeks due to instability in new snow and also from stressed weak layers, such as above ice crusts or buried surface hoar. Some weak layers persist on northerly and shaded slopes and some weak layers are becoming weaker due to rotting crusts. Watch the thermometer closely for the next week since these weak layers will be stressed by warming temps. Steep southerly slopes in direct sun could be unstable with the rotting crusts we’re finding.

The next avalanche advisory will be issued February 10th.

Have a safe and pleasant weekend!!!!

Contact: Kevin Davis (208) 265-6686, Ed Odegaard (208) 245-6209, or John Olson (208) 265-6635

This message is available by calling (208) 765-7323 or toll-free at 1-866-489-8664.

E-mail address: kevingdavis@fs.fed.us, eodegaard@fs.fed.us, jrolson@fs.fed.us, ebmorgan@fs.fed.us

 




You must be logged in to post comments. Please log in here or click the comment box below for options.

comments powered by Disqus
« Back to Outdoors blog

Rich Landers


Go to the full Outdoors page


Close

Sections


Profile

Close

Contact the Spokesman

Main switchboard:
(509) 459-5000
(800) 338-8801
Newsroom:
(509) 459-5400
(800) 789-0029
Customer service:
(800) 338-8801