THIS AVALANCHE ADVISORY EXPIRED ON March 10, 2018 @ 5:53 am
Avalanche Advisory published on March 9, 2018 @ 5:53 am
Issued by Ben Bernall - Kootenai National Forest

Kootenai

bottom line

Strong winds and storm-snow have created slabs above 5,000', use caution on all steep slopes over 35.°  Leeward terrain directly below ridgelines will be the primary features of concern at upper elevations through the weekend.  Expect to see loose-wet avalanche activity at lower elevations and use caution in areas where these slow moving slides have the potential to push you into high consequence terrain such as gullies, trees or cliffs.

How to read the advisory

Strong winds and storm-snow have created slabs above 5,000', use caution on all steep slopes over 35.°  Leeward terrain directly below ridgelines will be the primary features of concern at upper elevations through the weekend.  Expect to see loose-wet avalanche activity at lower elevations and use caution in areas where these slow moving slides have the potential to push you into high consequence terrain such as gullies, trees or cliffs.

2. Moderate

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Above Treeline
Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.

2. Moderate

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Near Treeline
Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.

2. Moderate

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Below Treeline
Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.
    Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.
Avalanche Problem 1: Wind Slab
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New storm snow and strong southwesterly winds have created windslabs on leeward terrain features above 5,000'. These wind slabs will continue to build through the day Friday. Steep slopes directly below ridgelines will be features of concern through the weekend.

Avalanche Problem 2: Storm Slab
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Area Snotel sites are showing up to 8" of new snow as of Friday morning. This storm came in warm and cooled off slightly with snow levels hovering just below 5,000'. These storm slabs are likely to be relatively thin and dense. Expect these slabs to be reactive throughout the day Friday until they have had a chance to bond with the older snow below it.

Avalanche Problem 3: Loose Wet
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Warm temperatures and rain below 5,000' will loosen the upper snowpack below treeline.  Expect to see loose-wet slides and extensive "pinwheels" at lower elevations. The loose snow that rests on top of last weekends crust will increase the risk of being entrained by one of these slides in steep terrain.

advisory discussion

It has been said that "change is our only constant". This summarizes our current snowpack situation in the mountains of North-west Montana right now. Yesterdays observations revelealed a stable, "right-side up" snowpack. As we descended we noted that the snow that was falling as light powder on the way up had transitioned to a warm, sticky mess at about 5,400'.  Extensive "rollers and pinwheels" bombed down the hill as the surface snow warmed up. In the afternoon a warm, moist and windy storm rolled into the area and deposited a fresh layer of snow. So, yesterdays very stable snowpack is now burdened with a new layer of storm snow and wind slab at the upper elevations. Considering it came in warm and cooled off slightly through the night it is likely to bond relatively quick. Looking at what we have out there right now and the long-term weather forecast I would expect that the snowpack may be dynamic and changing through the weekend with warm days and sunshine in the forecast.

The other observation worth noting is the weak layer on top of the February 4th rain crust. I hate to beat a dead horse; but, it is worth paying attention to as we transition to what looks to be very warm weather next week. This weakness is 4-5' deep in the Cabinets and showing no reactivity in stability tests. It could wake up next week as the warm and sunny days weaken the snowpack. If we enter into a cycle of warm days and cold nights it is likely that it will lock together without causing problems, only time will tell.

I would like to send out a big thanks to Kristen at the Cabinet Mountain Brewery and all the awesome folks from Libby and Troy that showed up for the Brews For Benefits last night! Very much appreciated.

Weather and CURRENT CONDITIONS
weather summary
Backcountry Forecast from NWS Missoula issued:
350 AM MST Fri Mar 9 2018

DISCUSSION: .SYNOPSIS...Expect widespread precipitation this morning ahead of
a cold front which will move across the region later this
afternoon and evening. Snow levels will begin around 4000-5000 
feet this morning and decrease through the day during/after cold 
frontal passage. Expect the best widespread snow accumulations
this morning through the noontime hour. Snow will become more
showery this afternoon and likely in bands. Snow showers will
diminish by mid evening as the cold front quickly exits the
region. The other impact from this system today will be gusty
winds of 20-30 mph through the afternoon hours. Some stronger 
showers this afternoon may contain even stronger gusts. 

Sunny and dry conditions will occur Saturday through Monday under
a building ridge of high pressure. Temperatures will warm up a bit
with overnight lows continuing well below freezing. 


Kootenai:
--------------------------- 5000-7000 FT ----------------------------
                      Today        Tonight      Sat      
Cloud Cover           85%          45%          25%      
Hi/Lo Temps           31 to 39     17 to 22     33 to 39 
Winds(mph)            SW 21G45     W  9G28      S  3     
Precip Chc            90           0            0        
Precip Type           snow         none         none     
Liquid Amt            0.14         0.00         0.00     
Snow Ratio(SLR)       15:1         0            0        
Snow Amt(in)          2-4          0            0        
Snow Level            3000         2500         1500     
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.