Battle between sun and wind

Location Name: 
Forecaster Observation - Triangle, Northern Flathead Range
Observation date: 
Wednesday, March 7, 2018 - 13:00
Is this an Avalanche Observation: 
No
Observation made by: Forecaster

Tabs

Quick Observation

Toured in the northern Flathead Range to look for wet loose activity and lingering wind slabs.

  • Sunny, bluebird day
  • 4-10" of snow above last weekend's sun crust
  • Observed a couple wet loose slides running on steep, gullied, and east facing aspects of Penrose above 6000 ft prior to winds picking up
  • Moderate southwest wind's with strong gusts above 5500 ft started around 10 am
    • Snow plumes off peaks above 6000 ft noted throughout the day
  • Sustained winds allowed air temperatures and snow surface to stay cool despite direct sunshine
  • Lots of pinwheels and rollerballs primarily observed below 6000 ft on sunny slopes
  • Shady, mid/ upper elevations slopes remained dry and provided the best skiing quality
  • Small, newly formed wind slabs were found on leeward slopes above 6000 ft
    • These were specific to below ridgelines and cross-loaded gully features that were reactive to ski cuts and didn't run far or entrain a large amount of snow
  • West through southeast aspects had a thin, breakable sun crust by late afternoon that made for some tricky skiing
  • Limited evidence of old, natural wind slab activity during prior 48 hours
Snowpack, Avalanche, Weather Images: 
Travel Details
Region: 
Flathead Range - Middle Fork Corridor
Route Description: 

Skiumah Creek to Triangle (7680 ft) and Deerlick Creek

Activity: 
Skiing
Snowpack Details
Snowpack and Weather Details: 
Hide Terrain
Elevation of observation: 
3500-5000 ft
5000-6500 ft
Above 6500 ft
Aspect(s) of observation: 
N
NE
E
SE
S
SW
W
NW
Red Flags: 
Blowing snow
Rollerballs / pinwheels
New Snow in the past 24 hours: 
0.00in.
More comments about the snowpack and weather: 
Snow surface on sunny aspects became wet, dense, and sticky from today's warm temperatures. Snow surface on shady mid/ upper elevation slopes remained cool and dry. Sun crust noted in the late afternoon on sunny aspects that warmed from today's sun and above freezing temperatures. Pinwheels and rollerballs were observed primarily below 6000 ft. Above 6000 ft, moderate winds kept snow surface cooler than at lower elevations. Specific and reactive wind slabs were found on upper elevation, leeward slopes and cross-loaded gullies below ridgelines.
Avalanche Details
Avalanche Details: 
Date and Time of Avalanche: 
Wednesday, March 7, 2018 - 14:00
Avalanche Type: 
Soft Slab
Failure Plane/Weak Layer: 
New/old snow interface
Hide Trigger
Trigger: 
skier
Trigger Modifier: 
Intentionally Triggered
Hide Terrain
Aspect: 
North
Starting Elevation: 
above-treeline
Hide Size
Destructive Size: 
D1 Relatively harmless to people.
Relative Size: 
R1 Very Small
Crown Height: 
Less than 1 ft
Avalanche Length (Vertical Run): 
100ft.
Avalanche Width (Average width): 
30ft.
Hide People Involved
Number of people caught: 
0
Number of partial burials: 
0
Number of full burials: 
0
Avalanche Location: 
Date and Time of Avalanche: 
Wednesday, March 7, 2018 - 09:00
Avalanche Type: 
Wet Loose
Failure Plane/Weak Layer: 
Within storm snow
Hide Trigger
Trigger: 
natural
Hide Terrain
Aspect: 
East
Starting Elevation: 
above-treeline
Hide Size
Destructive Size: 
D1 Relatively harmless to people.
Relative Size: 
R2 Small
Avalanche Length (Vertical Run): 
500ft.
Hide People Involved
Number of people caught: 
0
Number of partial burials: 
0
Number of full burials: 
0
Avalanche Location: