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.
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.
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!
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.
--------------------------- 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
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.
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