THIS SNOWPACK SUMMARY EXPIRED ON February 24, 2017 @ 10:45 pmSnowpack Summary published on February 24, 2017 @ 5:45 am
Issued by Ben Bernall - Kootenai National Forest
Avalanche Character 1: Storm Slab
Storm Slab avalanches release naturally during snow storms and can be triggered for a few days after a storm. They often release at or below the trigger point. They exist throughout the terrain. Avoid them by waiting for the storm snow to stabilize.
The Mountains of the Kootenai National Forest have 1-2' of snow that fell over the course of Presidents Day weekend above 6,000' in elevation. This new storm snow overlies a thick rain crust that developed on the rain event of February 16th. The new snow seems to have bonded well to the rain crust but harbors some thin weaknesses and density changes within the storm snow approximately 6" and 12" below the surface. These weaknesses have shown improvements in strength since Tuesday. The highest potential for human triggered avalanches exists on convex terrain features and steep northeasterly aspects above 6,000' where light winds have created a slightly more cohesive and thicker layer.
Bottom Line: Best option for travel safety this weekend is to approach steep, convexities and leeward terrain (north/easts aspects) with caution near ridgelines where light winds may have created a more cohesive slab in the upper snowpack. Triggering a small slab in these areas could step down to deeper layers within the storm snow.
For those of you who are out there riding and skiing you can help out your fellow riders (and me!) by posting your observations on this site. Simply click on the blue buttons in the observations section. You can also email me at firstname.lastname@example.org and let me know if you are seeing anything out there, start a slide or have a close call. With more info I can paint a better picture about conditions. The more recent the info the more relevant it will be to me and other users.
On Thursday February 23rd we traveled to Benning Mountain in the Keeler-Rattle drainage. Stability tests revealed weak layers 6" and 12" below the surface, extended column tests showed that these layers are unlikely to propagate into a slab avalanche. Stepping onto leeward aspects however one may find that the light winds have created a more cohesive layer where a rider could possibly trigger a slab in steep terrain. We observed what appeared to be avalanche debris in steep terrain at the bottom of Cliff Creek from earlier in the week. Other observations of note were the development of surface hoar on sheltered/shaded aspects and a thin sun crust on steep southerly terrain, this could become a problem once we recieve addtional snow. (Stay tuned.)
The view from the Benning Mt. Fire.
If you are riding near the Idaho Border check out the conditions near the Idaho Line by clicking the link below!
Weather and CURRENT CONDITIONS
Snow Level 0 0 0
Backcountry Forecast from NWS Missoula
issued: 340 AM MST Fri Feb 24 2017
DISCUSSION: A cold, showery regime will continue over the area today, bringing light snowfall amounts to western MT and keeping maximum temperatures well-below normal. A weak disturbance is anticipated on Saturday, initiating low- density snowfall and an increase in west winds. By Sunday, a more robust system will produce accumulating snowfall beginning over northwest Montana, and spreading into north-central Idaho and west- central Montana by late Sunday into Tuesday. Snow levels will remain down to valley floors, and temperatures will remain well- below normal.
--------------------------- 5000-7000 FT ----------------------------
Today Tonight Sat
Cloud Cover 70% 75% 70%
Hi/Lo Temps 20 to 26 6 to 13 21 to 26
Winds(mph) W 5 W 6 W 13G31
Precip Chc 0 0 40
Precip Type sno/shr sno/shr sno/shr
Snow Amt(in) 0 0 0
Snow Level 0 0 0
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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