Low angle pow grins just the same.

Location Name: 
Northern Whitefish Range
Observation date: 
Tuesday, February 16, 2021 - 19:00
Is this an Avalanche Observation: 
Yes
Observation made by: Professional Observer

Location

Tabs

Quick Observation

Today was a tour in the Whitefish Range.

  • One of our main objectives was to track the buried surface hoar on the south aspects.  And find it we did.  It was generally down in the snowpack about 2 feet deep, and a few inches above the obvious 1/13 crust.  However, it didn't show up until approx. 6500 feet.  Below that the 1/13 crust is capped with small facets.  While it wasn't broadly distributed, we found it in enough locations that we steered clear of steep terrain in the mid and upper elevations.
  • We did have several collapses today.  They were all above 6500', but it was difficult to predict where the next one would be.  Some openings would sound off, others wouldn't.  It was reason enough for us to choose the lower angled terrain.
  • Below 6000 feet there was a density change at the new/old interface approx 10 inches down.  This was more reactive in our tests than the 1/13 crust/facet combo until we got to about 6300 feet. We got a few propagating test results on the buried surface hoard between 6300 and 6700 feet on south and southwest aspects.
  • The snow surface above 6800 feet has surface hoar on it on all aspects.  
  • We saw plenty of avalanche activity from the last natural cycle, mainly confined to southeast, east, and northerly slopes above 6000 feet.  These avalanches were running on the buried surface hoar layer and were WIDE (some crowns were up to 1500 feet in width).  
Snowpack, Avalanche, Weather Images: 
Snowpack, Avalanche, Weather Videos: 

2/16/21 Managing Persistent Slabs

Travel Details
Region: 
Whitefish Range - Northern (north of Coal Creek)
Route Description: 

To 7200 feet

Activity: 
Skiing
Snowboarding
Snowmobiling
Snowpack Details
Snowpack and Weather Details: 
Hide Terrain
Aspect(s) of observation: 
NE
E
SE
S
SW
Red Flags: 
Collapsing / whumpfing noises
Persistent Weak Layers: 
Surface Hoar
Facets or Faceted Crust
On the surface
Buried
New Snow in the past 24 hours: 
2.00in.
Total Snow Depth: 
200cm
More comments about the snowpack and weather: 
Skies were mostly overcast with a few sucker-holes of blue sky mixed in. There was no wind, a good thing, as there is plenty of light snow available for transport. The top 6-8 inches is light, Fist hard, blower powder. Only right on the ridgeline we did skin over some wind board that was underneath the new light snow. 4 hasty pits between 6300 feet and 7000 feet on SW and S. CTE SP in all pits down 23 cm at the most recent storm interface (DFs). ECTPs with hard force down 58cm on buried, broken SH, on SW @ 6353 and S @ 6660. The slab above that layer is 4F with a very thin 1F sun crust is some openings from the sunny days in late Jan.
Blowing Snow: 
None
Wind Speed: 
Calm (No air motion)
Air temperature: 
Below Freezing
Snow line: 
Valley Floor
Sky Cover: 
Overcast (OVC)
Highest Precipitation Rate: 
Very Light Snowfall (S-1)
Avalanche Details
Avalanche Details: 
Date and Time of Avalanche: 
Saturday, February 6, 2021 - 02:00
Number of avalanches: 
6
Avalanche Type: 
Soft Slab
Failure Plane/Weak Layer: 
Old snow
More information or comments about the avalanche: 

Most north-northeast facing slopes on Whitefish Mtn and surrounding peaks had slid.

Hide Trigger
Trigger: 
natural
Hide Terrain
Aspect: 
Northeast
Starting Elevation: 
near-treeline
Hide Size
Destructive Size: 
D2 Could bury, injure, or kill a person.
Relative Size: 
R3 Medium
Crown Height: 
2 ft
Avalanche Location: 
Date and Time of Avalanche: 
Saturday, February 6, 2021 - 02:00
Number of avalanches: 
1
Avalanche Type: 
Soft Slab
Failure Plane/Weak Layer: 
Old snow
More information or comments about the avalanche: 

This slide wrapped around the bowl. The crown spanned NE-E-SE-S aspects. We confirmed that it failed on the buried SH layer.

Hide Trigger
Trigger: 
natural
Hide Terrain
Aspect: 
Northeast
Starting Elevation: 
above-treeline
Hide Size
Destructive Size: 
D3 - Could destroy a car, a wood house, or snap trees
Relative Size: 
R4 Large
Crown Height: 
2 ft
Avalanche Length (Vertical Run): 
1000ft.
Avalanche Width (Average width): 
1500ft.
Avalanche Location: