• Backcountry Avalanche Forecast
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Tue, Dec 11, 2018 at 6:53 AM
Issued by: Chris Bilbrey

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Tomorrow

Moderate (2) Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully.   Moderate (2) Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully.
Moderate (2) Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully.   Moderate (2) Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully.
Moderate (2) Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully.   Moderate (2) Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully.
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Summary

You can trigger an avalanche today.  Steep slopes with a stiff-over-soft layering near and above treeline have potential for large and dangerous avalanches. Steep slopes below treeline continue to be touchy. Recent avalanches have been triggered from a distance. If you want to reduce your risk to avalanches, avoid traveling on or below steep slopes facing northwest, north, northeast, east, and southeast.

Slopes with wind-drifted snow are the most hazardous. There are multiple layers of drifted snow, and an avalanche triggered near the surface could eventually rip them all out and entrain the entire season’s snowpack. Look for lens-shaped pillows on the sides of gullies, around rock outcrops, or below ridge lines to help identify these wind-pillow spots. Although smaller, wind-sheltered areas can produce avalanches too. You may want to avoid steep northerly or easterly-facing slopes that end in terrain traps like gullies or large stands of trees. Use shooting cracks or whumpfing collapses as indications of unstable snow and consider avoiding steep slopes if present.

 

Avalanche Problem

 
problem icon
N
S
E
W
NW
NE
SE
SW
Above Treeline
Near Treeline
Below Treeline
Certain
Very Likely
Likely
Possible
Unlikely
Historic
Very Large
Large
Small
Avalanche Character Aspect/Elevation Likelihood Size

What You Need to Know About These Avalanches


Persistent Slab avalanches can be triggered days to weeks after the last storm. They often propagate across and beyond terrain features that would otherwise confine Wind and Storm Slab avalanches. In some cases they can be triggered remotely, from low-angle terrain or adjacent slopes. Give yourself a wide safety buffer to address the uncertainty.

Avalanche Problem

 
problem icon
N
S
E
W
NW
NE
SE
SW
Above Treeline
Near Treeline
Below Treeline
Certain
Very Likely
Likely
Possible
Unlikely
Historic
Very Large
Large
Small
Avalanche Character Aspect/Elevation Likelihood Size

What You Need to Know About These Avalanches


Storm Slab avalanches release naturally during snow storms and can be triggered for a few days after a storm. They often release at or below the trigger point. They exist throughout the terrain. Avoid them by waiting for the storm snow to stabilize.

Avalanche Problem

 
problem icon
N
S
E
W
NW
NE
SE
SW
Above Treeline
Near Treeline
Below Treeline
Certain
Very Likely
Likely
Possible
Unlikely
Historic
Very Large
Large
Small
Avalanche Character Aspect/Elevation Likelihood Size

What You Need to Know About These Avalanches


Deep Persistent Slab avalanches are destructive and deadly events that can release months after the weak layer was buried. They are scarce compared to Storm or Wind Slab avalanches. Their cycles include fewer avalanches and occur over a larger region. You can triggered them from well down in the avalanche path, and after dozens of tracks have crossed the slope. Avoid the terrain identified in the forecast and give yourself a wide safety buffer to address the uncertainty.

Weather Forecast for 11,000ft Issued Tue, Dec 11, 2018 at 4:08 AM by Brian Lazar Statewide Weather Forecast
  Tuesday Tuesday Night Wednesday
Temperature (ºF) 25 to 30 10 to 15 25 to 30
Wind Speed (mph) 10 to 20 5 to 15 12 to 22
Wind Direction WSW WSW WSW
Sky Cover Decreasing Mostly Clear Mostly Cloudy
Snow (in) 0 to 2AM 0 0 to 2

Archived Forecasts

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Tue, Dec 11, 2018 at 7:52 AM
Issued by: Chris Bilbrey Statewide Weather Forecast  

The string of rider-triggered avalanches continues in the North San Juan zone with another one reported Monday on Red Mountain Pass. Avalanches, surface cracking, whumpfing collapses, and propagating stability test all point to unstable snow and should be a solid reminder that you can trigger a large and dangerous avalanche. You could trigger a slide from a distance and they could involve the entire season’s snowpack. 

In the race between the rabbit and the tortoise, you can think of weak faceted snow as the tortoise. Until the snowpack becomes deeper, these buried weak layers will only get worse before getting stronger. Time may be the best option. 

Surface instabilities gain strength more quickly and recent warm temperatures will help the surface snow consolidate. Slopes where thick and firm wind-drifted slabs exist above weak snow are most problematic and where we are seeing the most avalanche activity. These slopes are mostly found near and above treeline.

Steep slopes below treeline continue to be touchy in the North San Juan zone. These slopes are where the greatest uncertainty exists. On many below treeline slopes, the snow surface has transitioned to weak and cohesionless. Other below treeline slopes continue to produce propagating results in stability test indicating that the softer surface slab is still sensitive. Although avalanches in wind-sheltered areas may be smaller, you may want to avoid steep northerly or easterly-facing slopes that end in terrain traps like gullies or large stands of trees.

There is a west-to-east gradient in danger across the Southern Mountains with the bulls-eye of instability in the mountains around Silverton and Telluride. Evaluate snow and terrain carefully and identify wind-loaded terrain features of concern. This will help reduce your risk to avalanches. In the end if stability is the question, terrain is the number one answer.

 

 


  • Human triggered avalanche on Red 3 near Red Mountain Pass. (full)
  • Hwy side of Anvil Mtn (full)
  • Looking down a large remote skier trigger avalanche on the north aspect of Anvil. 12/9/2018 (full)
  • Skier-triggered avalanche Ophir Bowl 12.8.18 (full)

See more photos & videos

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Avalanche Observations
Report Date # Elevation Aspect Type Trigger SizeR SizeD
View Mon Dec 10 - TL NW SS AS / u R2 D2
View Sat Dec 8 - >TL W HS N R1 D1
View Sat Dec 8 - <TL E SS AS / u R1 D1.5
View Sat Dec 8 - >TL S WL N / u R1 D1.5
View Sat Dec 8 - >TL NE SS N / u R2 D2
View Sat Dec 8 - >TL N SS AS / u R2 D2

See All Avalanche Observations

Field Reports
Report Date Observer Snowpack Obs Avalanches Media
View Mon Dec 10 Jeff Davis No Yes (1) Yes (2)
View Mon Dec 10 Allen Riling No No Yes (1)
View Sun Dec 9 Amy Pertuz No No No
View Sun Dec 9 - No Yes (1) Yes (3)
View Sun Dec 9 Amy Pertuz No No Yes (1)
View Sat Dec 8 Amy Pertuz No Yes (1) No
View Sat Dec 8 Grady James No No No
View Sat Dec 8 Jeff Davis No Yes (3) Yes (4)

See All Field Reports

Weather Observations
Station Date Time Temperature Relative Humidity Wind Speed Wind Direction Max Gust 24 Hr Snow
Beartown Tue Dec 11 7:00 AM 23 - - - - 1.0
Dynamo Telluride Ski Resort Tue Dec 11 8:00 AM 19 95 19 238 26 -
Kendall Mt Tue Dec 11 7:00 AM 15 94 11 233 17 -
Molas Pass Tue Dec 11 7:00 AM 23 86 3 352 6 2.1
Putney Tue Dec 11 7:00 AM 20 92 14 280 34 -
Swamp Angel Tue Dec 11 7:00 AM 21 91 - - - 0.6
Lizard Head Pass Tue Dec 11 7:00 AM 26 - - - - -
Lone Cone Tue Dec 11 7:00 AM 30 - - - - 2.0

See All Weather Observations