THIS AVALANCHE ADVISORY EXPIRED ON March 28, 2018 @ 5:36 am
Avalanche Advisory published on March 27, 2018 @ 5:36 am
Issued by Ben Bernall - Kootenai National Forest

Kootenai

bottom line

Strong southwesterly winds and new snow will continue to build windslabs today. Expect to find windslabs on steep, leeward terrain at the upper elevations and in "cross-loaded" gullies where the wind has depostited the new snow. The most recent weather system is forecasted to bring rain to western Montana below 5,000' today, this will create perfect conditions for "loose-wet" avalanches through out the day Tuesday below treeline. 

How to read the advisory

Strong southwesterly winds and new snow will continue to build windslabs today. Expect to find windslabs on steep, leeward terrain at the upper elevations and in "cross-loaded" gullies where the wind has depostited the new snow. The most recent weather system is forecasted to bring rain to western Montana below 5,000' today, this will create perfect conditions for "loose-wet" avalanches through out the day Tuesday below treeline. 

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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Yesterday we observed strong and erratic winds that were creating thin slabs on leeward terrain and loading in gully features as it blew across the slopes. These slabs were not highly reactive and were showing a resistance to movement, the lack of a good "sliding surface" to move on was keeping these slabs in place yesterday. The strong winds forecasted will cause this problem to increase in danger during the day Tuesday, particularly on steep slopes and "extreme" terrain at upper elevations. Use caution in these areas and look for "lens-shaped" pillows of snow and take notice of changes in snow density as you travel.

Avalanche Problem 2: Loose Wet
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As the snowline rises today expect to see the most recent storm snow start to flow down the hill in a wet, sticky mess. The most recent storm snow is well bonded to the rain crust but it will flow easily once it starts raining. There is also the potential to see the sun on Wednesday which will create wet slides on any aspect, regardless of elevation. These avalanches will be slow in nature but have the potential to push you into spots where you don't want to be. Use caution in steep terrain above gullies, trees and cliffs where a slow moving wet-slide can increase your odds of getting hurt.

advisory discussion

On Monday March 26th we travelled into the South Fork of Callahan Creek. We observed evidence of wind-loading and cross-loading during the day but found the winds effects to be minimal in hazard due to the lack of a smooth and weak surface to move on. The wind effects were limited to a thin slab layer that resisted moving when triggered. I would expect these slabs to increase in thickness and sensitivity on Tuesday, potentially becoming more of a threat in exposed terrain above tree-line.

Stability tests conducted during the day revealed a very stable snowpack. Last Thursday the warm mountain temperatures and rain saturated the upper 12" of the snowpack, on Friday a cold, high pressure system caused temperatures to plummet as it pushed the moist weather out of the area. This left us with another thick crust layer (4" thick) and 12-14" of new snow that was found to be bonding well on all aspects observed yesterday. Looking forward into the week the weather is expected to be very windy and the snow-line is predicted to rise to over 5,000' across western Montana. Spring is a great time to remember that things can change from good to bad relatively quickly, rapid increases in temperature and wind will be the catalyst for reduced snowpack stability this coming week. Stay safe by paying attention to the weather and changing snow surface conditions as you ride!

Weather and CURRENT CONDITIONS
weather summary
Backcountry Forecast from NWS Missoula issued:
402 AM MDT Tue Mar 27 2018

DISCUSSION: A storm system will move through the region today
resulting in scattered showers with snow levels rising to 5000
feet during the afternoon. The biggest impact today will be strong
westerly winds sustained 15-30 mph with gusts of 40-50 mph, 
locally higher to 60 mph. Winds will diminish later this evening. 

Kootenai:
--------------------------- 5000-7000 FT ----------------------------
                      Today        Tonight      Wed      
Cloud Cover           95%          55%          40%      
Hi/Lo Temps           34 to 40     23 to 28     33 to 40 
Winds(mph)            SW 32G61     W 20G53      W  9G22  
Precip Chc            80           60           30       
Precip Type           sno/shr      sno/shr      sno/shr  
Liquid Amt            0.17         0.05         0.01     
Snow Ratio(SLR)       12:1         13:1         15:1     
Snow Amt(in)          1-4          0-1          0        

Snow Level            3500         5000         3000     
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.