Kootenai National Forest Avalanche Advisory – 3/25/2014

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 25, 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 Friday, March 28, 2014 by Jon Jeresek.


MOUNTAIN WEATHER 

WeatherGraphic

Since the Friday morning (March 21st) advisory,  amounts of snow (SWE 0.2- 0.6 inches) have fallen at all Kootenai snotel sites (Banfield Mtn, Bear Mtn, Hawkins Lake, Poorman Cr).  Winds Friday through Monday were light from the southwest. Temperatures at all sites have been below freezing day and night through Saturday. Thereafter, we have had above freezing temps Sunday and Monday afternoon. 

FORECAST:  Mostly cloudy skies Tuesday through Thursday.  All daytime temperatures are forecasted to be above freezing in the mid/upper 30s, with night time temperatures in the upper 20s.  Winds will be out of the southwest at 5 – 12 mph Tuesday through Thursday.  Chance of snow is 30-80% through Sunday with accumulations of 10- 12 inches forecasted.


 RECENT OBSERVATIONS

RecentObservationsGraphic

We traveled to Flatiron Mountain in the Purcell Range located 21 air miles north of Libby on March 24th.  70 to 75 inches of total snow depth was encountered on east aspects at 5,891 ft. elevation.   A 1 inch thick suncrust sits atop 4 inches of new snow.  Melt-freeze cycles have stiffened the upper layers of the snowpack.  There is no free water present in any layers of the snow column. The upper 20 inches of the snowpack releases with 8 – 12 inch drop heights using the stuff block test.  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.

   

 


 

  SNOWPACK DISCUSSION

Avalanche Problem #1

Wind Slab

Recent southwest wind events havetransported 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

WetAvalTemperatures are expected to be warmer tomorrow increasing the wet avalanche hazard, particularly on sun exposed slopes. Be aware of changing weather conditions, specifically rapidly rising temperatures. If travelling on or below sun exposed slopes consider turning around or moving to shaded areas if the snow surface becomes wet, skis or boots sink deep into the snow, or pin wheels or roller balls start to form on steep slopes.  

 

 


 

Avalanche Problem #3 

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: Heavy storm loading is the forecasted Tuesday monrning through Thursday with 0.5 inches of rain and 10-12 inches of new snow accumulations.  We expect light to moderate winds (5-15 mph) out of the southwest.  Temperatures are forecasted to be above freezing daytime in the mid/upper 30s, and night time in the upper 20s through Thursday.  The trend is for hazard to increase through this period. 


  BOTTOM LINE

The avalanche hazard in the West Cabinets, East Cabinets and Purcell Range is MODERATE but could increase with new snow and rain.  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:  Snowpack conditions have improved with melt-freeze cycles in the absence of storm loading, wind transport, or rain on snow events.  Next round of weather will include storm loading, possible rain on snow, and some wind transport. 


 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.