THIS SNOWPACK SUMMARY EXPIRED ON February 18, 2017 @ 12:25 pm
Snowpack Summary published on February 17, 2017 @ 7:25 pm
Issued by Ben Bernall - Kootenai National Forest
Avalanche Character 1: Loose Wet
Loose Wet avalanches occur when water is running through the snowpack, and release at or below the trigger point. Avoid very steep slopes and terrain traps such as cliffs, gullies, or tree wells. Exit avalanche terrain when you see pinwheels, roller balls, a slushy surface, or during rain-on-snow events.

Although we are dealing with a relatively stable snowpack we are entering that time of year when we are experiencing rapid changes in temperature from day to day.   Rising temperatures will have the potential to cause loose wet slides on aspects that are receiving intense afternoon sun.  

The best way to manage this potential hazard is to avoid steep slopes that are recieving intense, afternoon sun.  Plan your travels accordingly and pay close attention to the slopes that you may have to cross at the end of the day.

Avalanche Character 2: Persistent Slab
Persistent Slab avalanches can be triggered days to weeks after the last storm. They often propagate across and beyond terrain features that would otherwise confine Wind and Storm Slab avalanches. In some cases they can be triggered remotely, from low-angle terrain or adjacent slopes. Give yourself a wide safety buffer to address the uncertainty.

There are multiple rain crusts in the snowpack that are not currently reactive in stability tests; but, these layers provide the opportunity for avalanches that could be triggered by sun or the previously mentioned wet slides.

Again, the best option for dealing with these potential weaknesses is to avoid steep, sunny aspects in the afternoon and pay close attention to signs of a warming snowpack.

recent observations

 

Today (Friday, February 17th) we traveled into the Cabinet Mountain Wilderness near the Smearl Creek drainage. We found evidence of both loose wet slides and some small slab avalanches that appeared to have released during Thursdays rain event.  The rain left its mark as high as we could see on the highest peaks of the Cabinets (over 8,000").  As the rain left and the temperatures dropped the snowpack has stabilized significantly.  Stability test results showed a stable snowpack on a north aspect at 6,500'.  Southerly aspects were taking on alot of sun and some roller activity was  picking up but no slides were observed during the afternoon sun. 

 

If you are riding near the Idaho line check out the Panhandle Forecast by clicking the link below:

http://www.idahopanhandleavalanche.org/current-advisory.html

weather

Backcountry Forecast from NWS Missoula issued:

230 PM MST Fri Feb 17 2017



DISCUSSION:

Southwest flow will persist over the Northern Rockies for the next

couple of days with subtle disturbances making their way through

the flow. Snow levels will be fluctuating between 3000 to 5000

feet. This active weather pattern will persist through at least

mid next week.





Kootenai:



--------------------------- 5000-7000 FT ----------------------------

                                 Tonight       Sat             Sat Night    Sun     

Cloud Cover              60%            95%           95%            80%     

Hi/Lo Temps             21 to 25     31 to 34     23 to 28      31 to 36

Winds(mph)               E  7G21      SE  7          SW  7          SW  7   

Precip Chc                 0                80              100             60      

Precip Type               none          sno/shr      sno/shr        sno/shr 

Liquid Amt                0.00           0.17           0.16             0.06    

Snow Ratio(SLR)       0                14:1           15:1             16:1    

Snow Amt(in)            0                1                1-2               1       



Snow Level               3500         3000           2500            2500    

Disclaimer

This advisory applies only to backcountry areas outside established ski area boundaries. This advisory describes general avalanche conditions and local variations always occur. This advisory expires midnight on the posted day unless otherwise noted. The information in this advisory is provided by the USDA Forest Service who is solely responsible for its content.