Likelihood ?CertainVery LikelyLikelyPossible
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Fresh snow and stout winds out of the southwest yesterday created dense slabs of reactive snow just below ridgeline and steep rolls on north and easterly aspects. These slabs were mostly isolated to these locations and consequently small in size. It is very possible you will trigger something bigger if high-marking or dropping into steep and open terrain on these aspects. Use caution and watch for shooting cracks, and changes in surface density to alert you to these slabs. Yesterday they were making themselves obvious as can be seen in the photos below.
So, lets start with the good news.
The riding and skiing conditions are fantastic and generally the snowpack is quite stable across the area. Snowpack tests have produced pretty consistent results and shown the weak layers within the snowpack are unlikely to propagate into a slab avalanche. Yesterday we found one anomaly at 6,400' on a NE aspect that propagated with hard force, it did not propagate in the second test or in adjacent pit. This is really a good reminder of the fact that snow varies widely across aspects and elevations and you will not always see everything that is going on below the surface. SO, again the best way to deal with these unknowns is to be prepared and practice smart travel habits.
Fresh snow and strong winds! On the trip up yesterday in the East Cabinets we had moderate winds out of the North which switched mid-day to strong out ot the South and West. The loose, fresh snow was rapidly transported and forming fairly reactive slabs near ridgeline. Additional observations from the West Cabinets reported similiar conditions in Keeler Creek. The 6" of new snow was poorly bonded to the older snow but it was not slabby or likely to be a concern unless you are in an area where the wind worked its evil magic. In steep terrain you may get some light surface sloughing out of this new snow. as well. Lastly, hard to believe but it is now March. When the sun comes out (which it may this weekend) it will have some energy that we haven't seen in a while. Expect the new snow to form small wet slides on southerly aspects in steep terrain. Likely to be pretty harmless except in areas where they can entrain you and push you into trees or cliffs.
Backcountry Forecast from NWS Missoula issued: 510 AM MST Fri Mar 8 2019 DISCUSSION: Occasional snow showers are anticipated today and Saturday, most numerous in the afternoons with only an inch or two possible each day. Westerly winds on the terrain today are expected to diminish for Saturday. Skies clear with a dry period Sunday and Monday. Another weak weather system Tuesday into Wednesday will once again produce light to moderate snow accumulations. Temperatures will remain at below normal levels into next week. Kootenai: --------------------------- 5000-7000 FT ---------------------------- Today Tonight Sat Cloud Cover 65% 70% 55% Hi/Lo Temps 20 to 30 9 to 14 20 to 30 Winds(mph) SW 8G24 SW 10G21 SW 7 Precip Chc 30 20 0 Precip Type sno/shr snow snow Liquid Amt 0.02 0.01 0.00 Snow Ratio(SLR) 19:1 19:1 20:1 Snow Amt(in) 0-1 0 0 Snow Level 500 0 0
Avalanche conditions change for better or worse continually. Backcountry travelers should be prepared to assess current conditions for themselves, plan their routes of travel accordingly, and never travel alone. Backcountry travelers can reduce their exposure to avalanche hazards by utilizing timbered trails and ridge routes and by avoiding open and exposed terrain with slope angles of 30 degrees or more. Backcountry travelers should carry the necessary avalanche rescue equipment such as a shovel, avalanche probe or probe ski poles, a rescue beacon and a well-equipped first aid kit. For a recorded version of the Avalanche Advisory call (208)765-7323.
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