Kootenai National Forest Avalanche Advisory – 3/21/2014

The avalanche information for the Kootenai National Forest is provided by Kootenai National Forest personnel. The Flathead Avalanche Center hosts this information on its website for the Kootenai National Forest.

THIS ADVISORY HAS EXPIRED

Issued: March 21, 2014 at 7:00 a.m. by Jon Jeresek
Expires: 11:59 p.m. of issue date

This advisory applies only to backcountry areas outside established ski area boundaries. The next scheduled advisory for the Kootenai National Forest area will be Tuesday, March 25, 2014 by Jon Jeresek.


MOUNTAIN WEATHER 

WeatherGraphic

Since the Tuesday morning (March 18th) advisory, moderate amounts of snow (SWE 0.3 – 1.0 inches) have fallen at all Kootenai snotel sites (Banfield Mtn, Bear Mtn, Hawkins Lake, Poorman Cr).  Winds Tuesday through Thursday were from the southwest at variable speeds with moderate snow transport.  Temperatures at all sites have been below freezing day and night.  There is soft new snow available for wind transport at all sites in our ranges.

FORECAST:  Partly cloudy skies Friday through Sunday.  All daytime temperatures are forecasted to be near freezing in the low 30s F with night time temperatures in the low 20s F.  Winds will be extremely variable by direction at 3 – 5 mph.  Chance of snow is 20-50% through Sunday with accumulations of 2- 4 inches forecasted.


 RECENT OBSERVATIONS

RecentObservationsGraphic

We traveled to Cheer Ridge in the West Cabinets located 29 air miles west of Libby on March 20th.  Total snow depth was 125 to 130 inches on southeast aspects at 6,000’ elevation.  Four inches of new snow sits atop a 4 inch soft slab .  There is no free water present in any layers of the snow column. The upper 16 inches of the snowpack releases easily with a 4 inch drop height using the stuff block stress test.  The failing layer is 2 mm irregular columns.  The mid pack hard slabs release cleanly with hard force. The base of the snowpack shows depth hoar development as a result of the severe temperature gradients during the first week of February.  Currently, there are no significant temperature gradients in the snowpack to drive change processes.

View of Bear Mountain 6,061’ east side from Cheer Ridge. 3/20/2014.

View of Bear Mountain 6,061’ east side from Cheer Ridge. 3/20/2014.


Snowmobile play areas below Drift Peak. 3/20/3014,

Snowmobile play areas below Drift Peak. 3/20/3014,


Wind deposits near view and far from Cheer Ridge. 3/20/2014.

Wind deposits near view and far from Cheer Ridge. 3/20/2014.

 

 

 

 

 

 

 

 

 

   


 

  SNOWPACK DISCUSSION

Avalanche Problem #1

Wind Slab

Recent southwest wind events have “pillowed” snow onto east and northeast aspects.  From a distance these are quite obvious to the observer due their smooth, raised, rounded appearance.  Most of these slabs are hard and may have a hollow sound when traveled upon (NOT RECOMMENDED!).  Wind slabs should be identified and avoided. 

 

 

 


 

 Avalanche Problem #2 

CorniceCornice fall is the release of an overhanging mass of snow that forms when the wind moves snow over a sharp terrain features such as ridge.  Cornices range in size from small wind lips to huge overhangs of hard snow.  They can break off the terrain suddenly and trigger slab avalanches.  Cornice locations should be identified and avoided.

 

 

 

 


TREND:  Light storm loading is the forecasted Friday morning through Sunday with 2–4 inches snow accumulations.  Temperatures are forecasted to be near freezing daytime in the low 30s, and night time in the low 20s through Sunday.  


  BOTTOM LINE

The avalanche hazard in the West Cabinets, East Cabinets and Purcell Range is MODERATE.  This means that heightened avalanche conditions exist on specific terrain features, such as wind deposits.  Natural avalanches are unlikely, and human triggered avalanches are possible.  Evaluate snowpack and terrain carefully, identify features of concern.

SPECIAL NOTE:  Near surface layers (surface to 16 inches deep) release with ease but not cleanly.  Continued below freezing temperatures in the absence of storm loading, wind transport, and rain on snow will improve snowpack conditions. 


 DISCLAIMER

This advisory applies only to backcountry areas outside established ski area boundaries. This advisory describes general avalanche conditions and local variations always occur. This advisory expires 24 hours after the posted time unless otherwise noted. The information in this advisory is provided by the USDA Forest Service who is solely responsible for its content.