THIS SNOWPACK SUMMARY EXPIRED ON January 18, 2017 @ 10:30 pm
Snowpack Summary published on January 18, 2017 @ 5:30 am
Issued by Ben Bernall - Kootenai National Forest
Avalanche Character 1: Storm Slab
Storm Slab avalanches release naturally during snow storms and can be triggered for a few days after a storm. They often release at or below the trigger point. They exist throughout the terrain. Avoid them by waiting for the storm snow to stabilize.

Weather forecasts indicate that the incoming storm system will bring warm temps and significant moisture into the Kootenai Region.  This new snow and warmer temperatures will likely form a layer that is more dense than the existing surface layer that lies beneath it.  In many locations this new snow will fall on a layer of surface hoar that developed during the cold and calm conditions of the previous week. 

Although much of the danger is hard to pin down at this time due to the uncertainties of the incoming weather, it is highly likely that this new snow will be very reactive for the next couple of days.  Backcountry travelers should be aware that this new snow will be sensitive in areas that may surprise them and not look like typical avalanche terrain.  Be especially cautious in areas that are shaded and protected from sun and wind where surface hoar will be creating a weak point under the new snow load.  Open timber, steep gullies in drainage bottoms and any shaded aspect should be approached with caution until this storm snow has settled.

Avalanche Character 2: Wind Slab
Wind Slab avalanches release naturally during wind events and can be triggered for up to a week after a wind event. They form in lee and cross-loaded terrain features. Avoid them by sticking to wind sheltered or wind scoured areas.

Upper elevations within the Kootenai Region have been exposed to winds strong enough to transport the light surface snow during the past week.  We have observed these winds to be an issue primarily above 6,500' in elevation.  This hazard will rise in its potential and become more widespread as the incoming weather has predicted southwesterly winds in the teens with gusts up to 37 mph. 

Dealing with this problem will be a matter of avoiding steep, wind loaded slopes until the new snow has had time to strengthen and settle.  Look for a pillow like texture below ridgelines and within gullies.  Any observations such as shooting cracks or recent avalanches will be your obvious sign to find lower angle terrain that has not been subjected to recent wind loading.

Snowpack Discussion

For those riding near the Idaho Panhandle check out the advisory for additional info below at:

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

The report for last weeks fatality in Glacier Park has been released and may be viewed via the link below.  Our deepest condolonces go out to the friends and family for their loss.

http://www.flatheadavalanche.org/announcements/fri-01062017-0731/avalanche-fatality-stanton-mountain-glacier-national-park-152017

David Thompson Search and Rescue will be hosting a free avalanche course January 27th at the SAR Barn in Libby.  It will begin at 7PM on Friday night then resume at 7AM for a field day at Turner Mountain.  Interested parties may contact Terry Crooks for additional information at 406-293-1618.

recent observations

On January 17th Nate and I traveled into the North Fork Keeler drainage of the Western Cabinets.  The most interesting observation of note was the widespread surface hoar development that was observed on all aspects as high as 6,500'.   As I mentioned last week, stability tests have consistently showed very stable results; however, big changes can be expected with the incoming weather scenario.  Warmer conditions and heavy snow have the potential to create dangerous conditions as it buries this layer of surface hoar on steep, sheltered aspects.  On exposed ribs, ridgelines and southerly slopes we are seeing some sugary, faceted layers that will also create a weakness and ideal avalanche conditions once loaded by a layer of wet, cohesive snow.  All this is very much dependent on how the incoming storm shakes out.  I will be posting again Friday morning and should have a better picture going into the weekend, until then it is advisable to stick to lower angle terrain and remember that quick changes in weather often result in quick changes in avalanche conditions.  At this point we anticipate a rapid change in temperatures and snowloading.

weather

Backcountry Forecast from NWS Missoula issued:
410 AM MST Wed Jan 18 2017

DISCUSSION: Snow is spreading throughout north central Idaho and
northwest Montana this morning. Some of the lower elevations in
Idaho have been reporting rain, otherwise, snow is the dominate
precipitation type this morning. There are indications that the
vertical atmospheric profile will support light to moderate snow
at least through the morning. There are very warm mid- slope
temperatures in west central Montana ranging from the 30s to 40s.
A few of these spots may cool down to freezing with as
precipitation falls. Heavy wet snow over north-central Idaho
locations is expected today especially over the Clearwater
National Forest. While the majority of the precipitation will fall
today, snow and mixed precip will persist through Thursday.


Kootenai:

--------------------------- 5000-7000 FT ----------------------------
                                    Today             Tonight      Thu     
Cloud Cover                100%              95%            95%     
Hi/Lo Temps               32 to 36         25 to 30      32 to 37
Winds(mph)                SW 16G37      S 12G31      SW  9G21
Precip Chc                  100                100              100     
Precip Type                sno/fzra          snow           sno/shr 
Liquid Amt                 0.41                0.22             0.20    
Snow Ratio(SLR)       10:1                 11:1             10:1    
Snow Amt(in)            4-6                   2-4              2-4     

Snow Level               3500               4000            3500    
 

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.