THIS AVALANCHE ADVISORY EXPIRED ON December 25, 2019 @ 5:26 amAvalanche Advisory published on December 24, 2019 @ 5:26 am
Issued by
Ben Bernall - Kootenai National Forest
Kootenai

bottom line
Avoid steep terrain above 6,000' on north and east aspects. It will still be possible to trigger the recent storm snow in these locations and triggering small windslabs will be likely on high, steep terrain. These winds slabs and storm slabs will decrease in sensitivity during the week as temperatures return to seasonal normals and the winds subside.
Kootenai
How to read the advisory
Avoid steep terrain above 6,000' on north and east aspects. It will still be possible to trigger the recent storm snow in these locations and triggering small windslabs will be likely on high, steep terrain. These winds slabs and storm slabs will decrease in sensitivity during the week as temperatures return to seasonal normals and the winds subside.

3. Considerable
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Above Treeline
Dangerous avalanche conditions. Careful snowpack evaluation, cautious route-finding and conservative decision-making essential.
2. Moderate
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Near Treeline
Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.
1. Low
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Below Treeline
Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.
Dangerous avalanche conditions. Careful snowpack evaluation, cautious route-finding and conservative decision-making essential.
Avalanche Problem 1: Wind Slab
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Avalanche Problem 2: Storm Slab
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Last weekends storm brought massive amounts of moisture to the high peaks of the Kootenai. At "treeline" elevations it fell as a mix of rain and snow and has begun to stabilize as temperatures lower. Above 6,000' the moisture came in as all snow and is trending towards improved stability; but, it is still likely you will trigger a slide in the top 3-4 feet of the snowpack in steep terrain at upper elevations.
Avalanche Problem 3: Persistent Slab
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The base of our snowpack is housing some structural weakness consisting of early season ice layers sandwiched by weak sugary snow. These layers are now very deep and will likely be resistant to human triggering. These weak layers will become active as we add stressors such as last weekends warm temps and heavy amounts of moisture. Many avalanches ran on these deep weak layers last weekend as the snowpack took on the stress of added water weight and was weakened by above freezing temperatures.
advisory discussion
Last weekends storm delivered impressive amounts of moisture between Thursday evening and Sunday. Hawkins Lake Snotel recieved 5.3" of snow water equivalent (SWE) and Bear Mountain picked up 6.9" of SWE during this period. The snow line fluctuated up and down the hill during this period leaving us with an interesting scenario where tons of high elevation snow sits on the peaks but very little snow remains down low; thus, making the access for getting there less than awesome. During the storm lots of steep terrain avalanched at the elevation band where the temps were hovering just above the freezing mark. We observed many crowns yesterday that appeared to release on the deep weak layers (crust/facet combos), all the observed crowns were at 6,500' and below. At elevations above 6,500' we observed no recent avalanche activity but there is a thick, dense blanket of snow on north and east aspects due to the strong southwest winds that came in with the storm. The new snow is bonding relatively quickly as the temperatures return to seasonal norms.
During our tour we were also greeted with steady 15mph winds and strong gusts out of the southwest once on the ridgeline. These winds were continuing to build the windslab problem at the upper elevations and I was able to trigger small windslabs on test slopes with an easy ski-cut.
At lower elevations (below 5,000') there is very little snow left. Good news-low avalanche danger. Bad news-lots of brush to thrash through if you want to get to the snow up high.
Weather and CURRENT CONDITIONS
weather summary
Backcountry Forecast from NWS Missoula issued: 340 AM MST Tue Dec 24 2019 DISCUSSION: Widespread light snow accumulations are expected across west central and southwest Montana today with the passage of a weak low pressure system. Spotty snow showers will also occur in northwest Montana and north-central Idaho with only minimal accumulations. Winds will be light today. Wednesday and Thursday will be mostly dry across the entire Northern Rockies, aside of a few lingering showers on the terrain. Snowfall picks up again on Friday in northwest flow but amounts will be light, meanwhile westerly winds will increase on the terrain. Seasonable temperatures are anticipated throughout the week. Kootenai: --------------------------- 5000-7000 FT ---------------------------- Today Tonight Wed Cloud Cover 65% 65% 75% Hi/Lo Temps 24 to 31 15 to 20 22 to 28 Winds(mph) SW 8 SW 9G21 NW 8G20 Precip Chc 30 0 0 Precip Type snow none none Liquid Amt 0.01 0.00 0.00 Snow Ratio(SLR) 18:1 0 0 Snow Amt(in) 0 0 0 Snow Level 2000 1500 500
Disclaimer
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.
This website is owned and maintained by the Friends of the Idaho Panhandle Avalanche Center. Some of the content is updated by the USDA avalanche forecasters including the forecasts and some observational data. The USDA is not responsible for any advertising, fund-raising events/information, or sponsorship information, or other content not related to the forecasts and the data pertaining to the forecasts.