It depends on your definition of old snow....

Location Name: 
Forecaster Observation - Middle Fork/ Bear Creek corridor
Observation date: 
Thursday, February 14, 2019 - 15:30
Is this an Avalanche Observation: 
Yes
Observation made by: Forecaster

Tabs

Quick Observation

Took advantage of good visibility to survey slopes visible from Highway 2 looking for recent natural avalanches, particularly those that broke on old snow and indicate an ongoing Persistent Slab avalanche problem.

  • 5-10 large natural avalanches visible on very steep (40* or more) east-northeast slopes on high peaks between Nyack and Marias Pass (Nyack Mtn, Mt. Cameahwait, and Elk Mtn). From snow obscuring crowns and debris, estimate these failed late in the storm (2/12 or early 2/13). Most ran on steep aprons below rock bands; all occurred above 6500 feet. Impression that these involved storm and drifted snow that accumulated after 2/9 arctic intrusion. No crowns from very large avalanche crowns visible.
  • 15-20 small-large natural avalanches ons steep (35* or more) southeast and west facing slopes below 5000 feet. Several put debris on shoulder of Highway 2 or on railroad grade. Several may have been triggered by plowing operations on highway or railroad. Crown profile of one just below 5000 ft showed the 20-inch soft slab failed on a very thin layer of weak snow above a hard melt-freeze crust (formed on Groundhog Day Feb. 2). Other slides at this elevation looked to be similar depths. 

Some blowing snow at ridge crests from gusty/ moderate easterly winds. These seemed to increase as day progressed. Did not appear extensive enough to form widespread or thick slabs, though there might be some pockets of drifted snow sensitive to a person.

Snowpack, Avalanche, Weather Images: 
Travel Details
Region: 
Glacier National Park - Southern Lewis Range
Route Description: 

Binocular survey up Highway 2 up Middle Fork from West Glacier to Marias Pass and return

Snowpack Details
Snowpack and Weather Details: 
Hide Terrain
Elevation of observation: 
3500-5000 ft
Aspect(s) of observation: 
NE
E
SE
S
Red Flags: 
Blowing snow
Persistent Weak Layers: 
Facets or Faceted Crust
Buried
New Snow in the past 24 hours: 
0.00in.
Total Snow Depth: 
135 cm
More comments about the snowpack and weather: 
Partly cloudy in the AM; stratus moved in mid-afternoon from SW w clouds. Gusty east winds blowing snow at ridge crests, w small banners at ridges, more because snow low-density than winds strong. Winds veered to SE mid afternoon. Temps cool near Marias Pass. Crown profile on SS-N(?)-R2D1.5-O on SE facing slope above road at just under 5000 ft. 2/2 crust buried 50 cm by ~4F slab. Density change 5 cm above crust; some tests failing here but not propagating. CTM 13 RP on 2/2 crust, but very subtle. Repeated ECTs and CT, but couldn't see other failures in this layer. Not sure whether they didn't occur, or I just didn't see them.
Blowing Snow: 
Light
Wind Speed: 
Light (Twigs in motion)
Wind Direction: 
East
Air temperature: 
Below Freezing
Sky Cover: 
Partly Cloudy (SCT)
Avalanche Details
Avalanche Details: 
Date and Time of Avalanche: 
Tuesday, February 12, 2019 - 15:30
Avalanche Type: 
Unknown
Failure Plane/Weak Layer: 
Unknown
More information or comments about the avalanche: 

3-5 natural D2s on east face of Elk Mountain. Crowns partially visible; debris visible but both snow-covered. Looks like drifting as well as storm snow. 

Hide Trigger
Trigger: 
natural
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Start Zone Slope Angle: 
40
Aspect: 
East
Starting Elevation: 
above-treeline
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Destructive Size: 
D2 Could bury, injure, or kill a person.
Avalanche Location: 
Date and Time of Avalanche: 
Wednesday, February 13, 2019 - 06:00
Avalanche Type: 
Soft Slab
Failure Plane/Weak Layer: 
Old snow
More information or comments about the avalanche: 

Natural avalanches on southeast-facing slopes in the Bear Creek corridor, between Java East and Marias Pass. Includes several above BNSF Railroad in the Shed 4.5 area. Several others on W facing slopes; these were not as common. Data about slab and failure layer from crown profile of slide at ~5000 ft just above Hwy 2. Slab def failed on 2/2 crust, but weak layer very thin. 5-8 cm recent snow on bed surface. 

Hide Trigger
Trigger: 
natural
Hide Terrain
Start Zone Slope Angle: 
38
Aspect: 
Southeast
Starting Elevation: 
below-treeline
Hide Size
Destructive Size: 
D1.5
Relative Size: 
R2 Small
Crown Height: 
2 ft
Avalanche Length (Vertical Run): 
75ft.
Avalanche Width (Average width): 
75ft.
Date and Time of Avalanche: 
Tuesday, February 12, 2019 - 16:15
Avalanche Type: 
Unknown
Failure Plane/Weak Layer: 
Unknown
More information or comments about the avalanche: 

Natural avalanches on east faces of Nyack Mountain and Mt. Cameahwait, breaking either at ridgelines or on steep aprons below cliffy areas. Crowns inditinct; debris piles evident from shape but both crowns and debris snow covered, w drifted snow as well as recent storm snow. Slides look to have run to mid track. Start zones more east-northeast than due east. 

Hide Trigger
Trigger: 
natural
Hide Terrain
Start Zone Slope Angle: 
40
Aspect: 
East
Starting Elevation: 
above-treeline
Hide Size
Destructive Size: 
D2.5
Relative Size: 
R3 Medium
Avalanche Length (Vertical Run): 
400ft.
Avalanche Width (Average width): 
150ft.
Avalanche Location: