Likelihood ?CertainVery LikelyLikelyPossible
Size ?HistoricVery LargeLarge
The persistent slab problem that we have been discussing is unlikely to move at this point without a drastic weather change. Below 5,500' it is very much "bridged" by a thick rain crust. Above this elevation I would continue to use caution in extreme terrain and continue to practice safe travel habits as there is always potential to find a weak spot and trigger one of these weaknesses.
Yesterdays' travels took us up an easterly aspect up to 7,000' in the Cabinet Mountains. Pit results on the easterly aspect were fairly uneventful with some failures in the top 12" of snow between crust layers and none showing the likelihood to propagate. Still finding facets at the base of the snowpack in thinner areas but they continue to show progress and gain strength. Another pit done on a north aspect at 7,000' revealed no weaknesses in the upper snowpack and showed a nice progressive density increase with increased depth "right side up!" We observed a couple of small crowns and older wet slides that likely released during last Thursdays rainy and warm weather. No slides were observed yesterday despite the abundance of sunshine at upper elevations.
The real story right now is what may come in the future. With the current high pressure and temperature inversion we are under there is an abundance of surface hoar growing on all aspects that we observed up to 6,000', I believe it is likely you may find it at higher elevations in other locations; but, it seems with the upper elevations recording warmer temps, the growth of surface hoar is likely stunted and less prevalant. Below 5,500' this surface hoar is growing on a thick, hard rain crust, this will be a significant issue once it begins to snow. It is really the perfect recipe for creating touchy avalanche conditions at lower elevations that may take some time to heal. So, with the current stable conditions expect the potential to undergo a big change by the weekend at treeline and below. Watch the video below for a quick summary of yesterdays observations.
Surface hoar crystals .5-1cm in length
Backcountry Forecast from NWS Missoula issued: 410 AM MST Tue Jan 15 2019 DISCUSSION: A cooling trend is being observed in the high elevations, that will continue through today. Moisture is also increasing; weak waves of moisture will promote light snow out of existing stratus. Light snow arrives to the high terrain by this evening with minor accumulations. Models remain on track for a long duration snow event Thursday and Friday with easterly winds. 48 hour snow totals currently range from 6-8 inches with SWE 0.30-0.50 inches. Kootenai: --------------------------- 5000-7000 FT ---------------------------- Today Tonight Wed Cloud Cover 35% 55% 65% Hi/Lo Temps 28 to 34 12 to 19 26 to 31 Winds(mph) E 7 E 6 E 6 Precip Chc 0 30 30 Precip Type flurries snow snow Liquid Amt 0.00 0.01 0.02 Snow Ratio(SLR) 11:1 19:1 17:1 Snow Amt(in) 0 0 0 Snow Level 2000 1500 1500
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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