Kootenai National Forest Avalanche Advisory – 4/4/2014

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: April 4, 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. This is the last scheduled advisory for the Kootenai National Forest area. 


MOUNTAIN WEATHER 

WeatherGraphic

Since the Tuesday morning (April 1st) advisory, only small amounts of snow (SWE 0.0- 0.2 inches) fell at Kootenai snotel sites (Banfield Mtn, Bear Mtn, Hawkins Lake, Poorman Cr).  Winds on Friday through Monday were light from the southwest.  All sites experienced melt-freeze cycles through Monday with night time low temperatures in the upper 20s F and day time highs in the low 40s F.  

FORECAST:  Cloudy skies Friday through Sunday.  All daytime temperatures are forecasted to be above freezing in the low 40s F with night time temperatures in the upper 20s F.  Winds will be from the west/southwest direction at 13 – 17 mph.  Chance of snow is 50-90% through Sunday with 8 – 12 inches forecasted.


 RECENT OBSERVATIONS

RecentObservationsGraphic

We traveled to Chicago Peak in the East Cabinets located 23 air miles south of Libby on April 3rd.  Total snow depth was about 100 inches on west aspects at 6,000 feet elevation.   A three inch knife hard crust sits on top of a five inch one finger hard slab.  Below these surface layers is a four inch pencil hard slab that releases cleanly (Quality 1 shear) with moderate force in stability tests.  Below these top layers are very hard crusts and hard slab several feet thick.  The upper 20 inches of the snowpack releases roughly (Quality 3 shears) with moderate force in compression (stability) tests.  Currently, there are no significant temperature gradients in the snowpack.


 

SNOWPACK DISCUSSION

Avalanche Problem #1

Wind Slab

Southwest wind events transport snow onto east and northeast aspects. Wind slabs can take up to a week to gain strength, and steep wind loaded slopes should still be treated as suspect. It remains important to assess the stability of each slope you intend to ski or ride. From a distance these will be quite obvious due their smooth, raised, and rounded appearance.  Most of these slabs are hard and may have a hollow sound.  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 are easily identified and should be avoided.

 

 


TREND: Moderate to heavy storm loading (8-12 inches) is forecasted Friday morning through Sunday.  I expect wind transport (southwest/west 13 – 17 mph) of this new snow.  Temperatures are forecasted to be above freezing during the day in the low 40s, and night time in the upper 20s through Sunday.  The trend is for avalanche hazard to increase through this period due to new snow and wind.


 

  BOTTOM LINE

For today, 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.  Natural avalanches are unlikely, and human triggered avalanches are possible.  Evaluate snowpack and terrain carefully, identify features of concern.

Snowpack conditions have improved with melt-freeze cycles in the absence of storm loading, wind transport, or rain on snow events.  Forecast is for storm loading and wind transport through Sunday.  The trend is for avalanche hazard to increase through this period due to new snow and wind.


 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.