THIS SNOWPACK SUMMARY EXPIRED ON January 4, 2017 @ 12:00 am
Snowpack Summary published on January 3, 2017 @ 7:00 am
Issued by Ben Bernall - Kootenai National Forest
Avalanche Character 1: Wind Slab
Wind Slab avalanches release naturally during wind events and can be triggered for up to a week after a wind event. They form in lee and cross-loaded terrain features. Avoid them by sticking to wind sheltered or wind scoured areas.

New Years day brought 6-8" of fresh snow to the Snotel Sites throughout the Kootenai National Forest.  This new snow was quickly followed by northeasterly winds that accompanied the ensuing cold front.  This has resulted in significant wind loading on the south and westerly aspects as well as some dense slab formation on the north and east aspects.  Yesterdays travels in the Eastern Cabinets found this problem to exist primarily above 5,000' on open and exposed terrain.  Cracking was observed in the top 8" of snow yesterday on convex rolls and within close proximity to ridgelines.

Backcountry travelers can mitigate this potential hazard by playing and riding on timbered slopes that are protected from the wind.  Use caution on steep convex rolls and near ridgeliness where the wind is forming a cohesive slab layer.

Snowpack Discussion

On January 2nd we traveled into the East Cabinets where we found approximately 8" of fresh snow and cold temperatures.  Winds were light out of the northeast with stronger gusts near the ridgelines (15-20mph).  The top 8" of the snowpack was dense in the open exposed areas, slabby and reactive near the ridgeline and light and fluffy where protected by the timber.  We dug pits and did stability tests on southeast and northeast aspects at approximately 6,000'.  Pit results revealed a relatively stable snowpack that was progressively denser with depth.  Stability test results showed easy failures in the top 8" where the new snow had not yet bonded to the existing snowpack, this layer is currently only a concern where it is exposed to the wind and forming a cohesive slab.   We found a buried layer of surface hoar 24" below the surface that was failing with hard force and no propagation.  This weakness has been showing up consistently throughout the mountains of the Kootenai; however, the surface hoar crystals appear to be breaking down and bonding well to the surrounding layers.

This weeks weather is forecast to be very cold with a chilly northeast wind.  Make sure you have the neccessary gear to survive the unexpected situation and remember that an injury or equipment breakdown situation will become much more dire in these temperatures.  Keep this in the forefront of your mind when making decisions in the mountains.

 

recent observations

For folks venturing into the country near the Idaho State line be sure to check out the Panhandle forecast for additional information at http://www.idahopanhandleavalanche.org/current-advisory.html

Also, you can help us out by submitting your avalanche observations on the Kootenai by clicking on the tabs to the left.  Any additional info is helpful!

weather

Backcountry Forecast from NWS Missoula issued:

430 AM MST Tue Jan 3 2017



DISCUSSION: Cold and dry weather is expected through most of this

week. Easterly winds are expected to gradually decrease throughout

the day today but another increase in easterly winds will be

possible during the day Wednesday (mainly for ridge tops).


Temperatures will gradually begin to warm late Thursday into

Friday as a ridge of high pressure builds over the Northern

Rockies. The next weather system is expected on Sunday and models

are in a fairly good agreement for a warm and moist system moving

through the region.





Kootenai:



--------------------------- 5000-7000 FT ----------------------------

                                     Today            Tonight           Wed     

Cloud Cover                  40%              30%                 10%     

Hi/Lo Temps                 0 to 5           -13 to -5           0 to 4  

Winds(mph)                  NE  9G23       NE  9G20         NE  9G23

Precip Chc                    0                    0                      0       

Precip Type                  none              none                none    

Liquid Amt                   0.00               0.00                 0.00    

Snow Ratio(SLR)          0                    0                      0       

Snow Amt(in)               0                    0                      0       



Snow Level                  0                    500                 500     

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 midnight on the posted day unless otherwise noted. The information in this advisory is provided by the USDA Forest Service who is solely responsible for its content.