Avalanches on Nyack

Location Name: 
Forecaster Observation - Flathead Range
Observation date: 
Tuesday, March 23, 2021 - 21:00
Is this an Avalanche Observation: 
Yes
Observation made by: Forecaster

Location

Tabs

Quick Observation

We enjoyed a day off, sampling the fresh snow in the Middle Fork. 

  • There were four inches of recent snow at 4000 feet and 8 to 10 inches at 6000 feet.
  • Cloud cover limited wet loose activity to a handful of small slides on steep southerly slopes. Steep northerlies had a few small dry loose sluffs which probably occurred during the storm overnight.
  • We observed several storm slabs at upper-elevations on the east face of Nyack Mountain. It appears that debris from the higher slabs triggered the lower slabs.
  • Dry snow sluffing on steep northerly aspects was common with ski turns. These were large enough to push you around and ran several hundred feet. 
  • Aspects that received sun during the day had a 1 to 2 inch surface crust by late afternoon.

 

Snowpack, Avalanche, Weather Images: 
Travel Details
Region: 
Flathead Range - Middle Fork Corridor
Activity: 
Skiing
Snowpack Details
Snowpack and Weather Details: 
Hide Terrain
Elevation of observation: 
3500-5000 ft
5000-6500 ft
Aspect(s) of observation: 
N
NE
SE
S
Red Flags: 
Avalanches from the past 2 days
Rapid or prolonged warming
Rollerballs / pinwheels
Persistent Weak Layers: 
Facets or Faceted Crust
On the surface
New Snow in the past 24 hours: 
6.00in.
More comments about the snowpack and weather: 
The surface snow on northerlies became moist below 5000 feet later in the day. Above this elevation, the snow stayed cohesionless. The surface of southerlies became moist early but was not sticky and allowed for easy traveling.
Air temperature: 
Above Freezing
Snow line: 
4000'
Avalanche Details
Avalanche Details: 
Date and Time of Avalanche: 
Tuesday, March 23, 2021 - 10:00
Number of avalanches: 
10
Avalanche Type: 
Wet Loose
Failure Plane/Weak Layer: 
Within storm snow
More information or comments about the avalanche: 

These occurred early in the day from solar input.

Hide Trigger
Trigger: 
natural
Hide Terrain
Start Zone Slope Angle: 
35
Aspect: 
Southeast
Starting Elevation: 
near-treeline
Hide Size
Destructive Size: 
D1 Relatively harmless to people.
Relative Size: 
R1 Very Small
Avalanche Length (Vertical Run): 
150ft.
Avalanche Width (Average width): 
25ft.
Avalanche Location: 
Date and Time of Avalanche: 
Monday, March 22, 2021 - 22:00
Number of avalanches: 
5
Avalanche Type: 
Loose Dry/ Sluff
Failure Plane/Weak Layer: 
Within storm snow
More information or comments about the avalanche: 

These appeared to have run during the storm.

Hide Trigger
Trigger: 
natural
Hide Terrain
Start Zone Slope Angle: 
40
Aspect: 
North
Starting Elevation: 
near-treeline
Hide Size
Destructive Size: 
D1 Relatively harmless to people.
Relative Size: 
R1 Very Small
Avalanche Length (Vertical Run): 
100ft.
Avalanche Width (Average width): 
20ft.
Avalanche Location: 
Date and Time of Avalanche: 
Tuesday, March 23, 2021 - 16:00
Number of avalanches: 
6
Avalanche Type: 
Loose Dry/ Sluff
Failure Plane/Weak Layer: 
Within storm snow
More information or comments about the avalanche: 

It was impossible not to trigger sluffs on steep northerly slopes we traveled. None of these appeared to slide on or step down to the crust.

Hide Trigger
Trigger: 
skier
Trigger Modifier: 
Intentionally Triggered
Hide Terrain
Start Zone Slope Angle: 
40
Aspect: 
Northeast
Starting Elevation: 
near-treeline
Hide Size
Destructive Size: 
D1.5
Relative Size: 
R1 Very Small
Avalanche Length (Vertical Run): 
300ft.
Avalanche Width (Average width): 
20ft.
Avalanche Location: