THIS AVALANCHE ADVISORY EXPIRED ON January 12, 2020 @ 7:57 am
Avalanche Advisory published on January 11, 2020 @ 7:57 am
Issued by Ben Bernall - Kootenai National Forest

Kootenai
Selkirks/Cabinets
St. Regis Basin/Silver Valley

bottom line

Heavy snowfall and strong winds entered the area on Friday and will continue to impact the mountains of North Idaho and Northwest Montana throughout the weekend. Avoid riding on or below steep terrain this weekend as the new storm will be easily triggered.  Avalanche paths and runouts will also be of concern as slides could step down to deeper weak layers and run long distances. 

How to read the advisory

Kootenai
Selkirks/Cabinets
St. Regis Basin/Silver Valley

How to read the advisory

Heavy snowfall and strong winds entered the area on Friday and will continue to impact the mountains of North Idaho and Northwest Montana throughout the weekend. Avoid riding on or below steep terrain this weekend as the new storm will be easily triggered.  Avalanche paths and runouts will also be of concern as slides could step down to deeper weak layers and run long distances. 

4. High

?

Above Treeline
Very dangerous avalanche conditions. Travel in avalanche terrain not recommended.

4. High

?

Near Treeline
Very dangerous avalanche conditions. Travel in avalanche terrain not recommended.

3. Considerable

?

Below Treeline
Dangerous avalanche conditions. Careful snowpack evaluation, cautious route-finding and conservative decision-making essential.
    Very dangerous avalanche conditions. Travel in avalanche terrain not recommended.
Avalanche Problem 1: Storm Slab
  • Type ?
  • Aspect/Elevation ?
  • Likelihood ?
    Certain
    Very Likely
    Likely
    Possible
    Unlikely
  • Size ?
    Historic
    Very Large
    Large
    Small

It's coming down hard out there with more snow on the way! If you are going into the mountains today show up with a conservative plan and mindset. New storm snow will slide easily as much of it is falling on a weak interface of graupel that fell during the last storm. Human triggered avalanches are likely today in any terrain over 30° and will likely remain that way until the storm snow has ample time to settle out.

Avalanche Problem 2: Wind Slab
  • Type ?
  • Aspect/Elevation ?
  • Likelihood ?
    Certain
    Very Likely
    Likely
    Possible
    Unlikely
  • Size ?
    Historic
    Very Large
    Large
    Small

Strong southwest winds will continue to load north and east aspects today and add to the sensitivity of the conditions on leeward terrain. Weather forecasts are also predicting a substantial wind shift as a cold front enters the area late Sunday as well.

advisory discussion

Let's keep it simple today. Rapid loading and strong winds are never good for stability.  Avoid all steep slopes, avalanche paths and runouts this weekend. 

On Thursday all zones were finding that the previous storm snow was settling and making it's way towards stability.  However, we were also finding weak layers close to the surface of the last storm snow and deeper weak layers that could be activated and sensitive as they adapt to a new load of storm snow.

Weather and CURRENT CONDITIONS
weather summary 
Backcountry Forecast from NWS Missoula issued:
340 AM MST Sat Jan 11 2020

DISCUSSION:  

NORTHWEST MONTANA: A second surge of significant moisture will be
moving into Northwest Montana this morning, bringing another round
of moderate to heavy snow to the region through this evening. The
higher snow amounts will be in the higher terrain along the Idaho
Panhandle, where another foot of snow is expected along with 
isolated higher amounts. Breezy southwest winds up to 30 mph for 
elevations above 5000 feet will continue. An even stronger system,
with more moisture is poised to move into the area Sunday night 
into Monday. At the same time, an arctic push will drop south out 
of Canada Sunday evening into Monday. The artic front and airmass 
is expected to make it as far west as the Whitefish range. Gusty 
northeast winds and significantly colder temperatures are 
anticipated along this boundary. Next week will be much colder 
with continued periods of snow. 
NORTH CENTRAL IDAHO: Another surge of pacific moisture will bring
a second round of moderate to heavy snow to the mountains above
the Highway 12 corridor this morning through the evening hours
tonight. Another 10 to 15 inches of snow is expected in the higher
terrain. Light but persistent snow will likely continue through 
Sunday before an even stronger surge of moisture increases 
snowfall intensity Sunday evening into Monday. Much colder 
temperatures are expected by early next week with continued 
periods of snow likely.

Kootenai:
--------------------------- 5000-7000 FT ----------------------------
                      Today        Tonight      Sun      
Cloud Cover           95%          90%          95%      
Hi/Lo Temps           24 to 30     16 to 22     21 to 27 
Winds(mph)            S 15G31      SW 19G36     SE 15G32 
Precip Chc            90           90           90       
Precip Type           snow         snow         snow     
Liquid Amt            0.29         0.20         0.26     
Snow Ratio(SLR)       17:1         18:1         20:1     
Snow Amt(in)          4-11         3-9          5-8      

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.