• Backcountry Avalanche Forecast
  • Forecast Discussion
  • Observations & Weather Data

Thu, Mar 4, 2021 at 7:39 AM
Issued by: Chris Bilbrey

Thursday

 

Friday

Considerable (3) Dangerous avalanche conditions. Cautious route-finding and conservative decision-making essential.   Considerable (3) Dangerous avalanche conditions. Cautious route-finding and conservative decision-making essential.
Considerable (3) Dangerous avalanche conditions. Cautious route-finding and conservative decision-making essential.   Considerable (3) Dangerous avalanche conditions. Cautious route-finding and conservative decision-making essential.
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.
  Danger Scale

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Summary

3 to 5 inches of dense snow accumulated across the South San Juan overnight with up to 8 inches near Wolf Creek Pass. The new snow fell onto a variety of old snow surfaces and will be reactive to the weight of a rider or machine. Slopes with more than about 8 inches of new or drifted snow are the most dangerous and slides there could grow large enough to bury a person. Southwest winds are forming thicker drifts at higher elevations. Avoid areas of slopes where the snow appears deepest or forms smooth, rounded pillows of wind-affected snow.

Slides triggered from a wind-drifted area of the slope will be larger and could potentially trigger a more dangerous slide breaking deeper in the snowpack. The looming threat of a deep, wide, and very large avalanche still lingers on northwest through east to southeast-facing slopes. You are more likely to trigger one of these monster avalanches where the snowpack is shallow and weaker snow is closer to the surface. Cracking and collapsing suggest potential danger and stick to low-angle slopes below treeline, without avalanche terrain above you, for safer riding options

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Please remember to recreate responsibly, including following state and local public health orders and social distancing recommendations.

 

Avalanche Problem

 
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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

 
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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


Wind Slab avalanches release naturally during wind events and can be triggered for up to a week after a wind event. They form in lee and cross-loaded terrain features. Avoid them by sticking to wind sheltered or wind scoured areas.

Weather Forecast for 11,000ft Issued Fri, Mar 5, 2021 at 4:20 AM by Mike Floyd Statewide Weather Forecast
  Thursday Thursday Night Friday
Temperature (ºF) 32 to 37 15 to 20 33 to 38
Wind Speed (mph) 5 to 15 2 to 12 8 to 18
Wind Direction NNE SW SW
Sky Cover Clear Clear Mostly Clear
Snow (in) 0 0 0

Archived Forecasts

  • Select Forecast: Valid

Thu, Mar 4, 2021 at 8:14 AM
Issued by: Chris Bilbrey Statewide Weather Forecast  

A warm, moist storm systems arrived overnight forming fresh Storm Slabs at all elevations. With a mix-bag of old, snow surfaces below the new snow, dense slabs will be reactive to the weight of a rider. Sensitivity may be a bit touchier on northerly-facing slopes where the old snow surface faceted and weakened during the recent warm, dry spell. In addition, firm melt-freeze crust on slopes facing east through south to west may act as a slippery sliding surface and avalanches can travel farther and faster than you might expect.

Since mid-February, the snowpack is less reactive and terrifying avalanche activity has dropped off significantly. The majority of stability test are not popping off the column with excitement ending up in your lap. Despite our Persistent Slab avalanche problem trending down over the last week, looming weak layers have been cranky all season. Storm Slab avalanches triggered from deeper drifts could trigger deeply buried persistent weak layers. This cascade event would result in deeper failures and wider propagating contributing to a more deadly and destructive avalanche. 

Initiating a failure in deeply buried weak layers below a stiff slab takes finding the right combination of depth and structure or the shallow spot on a slope. Stepping out into terrain near 35 degrees at higher elevations is like rolling the dice. Slopes harboring the right combination of depth and structure may tolerate multiple people traveling across or below without avalanching providing a false sense of security. During times like this, it does not matter how much you know about snow, avalanches, or how many years you have spent in the backcountry, recreating on steeper slopes is purely a game of chance.

Weak, fragile facets that formed in December keep rearing their ugly head and surprising observers with lingering sensitivity. A large remotely triggered avalanche outside of Lake City this week is a good reminder that weak snow lurking below can still fail from added weight of a rider or machine. Stubborn slabs may not offer clues of potential danger prior to failure and may even lure you further out onto a slope before breaking above and around you. You can reduce the chance of waking the monsters in the basement by sticking to lower angle slopes without overhead hazards or below treeline slopes.

If uncertainty surrounds your snowpack assessment or you are new to the backcountry, now is not the time to explore bigger, more complex terrain. If you are an old veteran, now is not the time to rely on what you have done in past years. Patience is a strong attribute and know that the snowpack will turn around, but it is not there yet.


  • NW near treeline snowpit from the South San Juan near Molas Pass 3/32021 (full)
  • 1 to 3 mm facets (4F) still linger at the base of the snowpack on many northerly and easterly-facing slopes near and above treeline. Extended Column Tests did not produce propagating failures in this snowpit, but Compression Test still highlight these weaker grains with sudden collapse failures. Though more stubborn to triggering, a slide breaking this deep would be large and dangerous. South San Juan. 3/2/21. (full)
  • Hand hardness profile for a snowpit on an east-southeast aspect at 12,550 feet. South San Juan. 2/26/21. (full)
  • A thick melt-freeze crust with softer snow below found on east to south aspects below treeline. Moderate winds kept snow surfaces cool despite clear, sunny skies. This crust was barley breakable on many slopes by the afternoon - zip away! South San Juan. 2/26/21. (full)

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Avalanche Observations
Report Date # Elevation Aspect Type Trigger SizeR SizeD
View Tue Mar 2 - >TL S WL N - D1.5
View Tue Mar 2 - TL S WL N - D1

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Field Reports
Report Date Observer Snowpack Obs Avalanches Media
View Thu Mar 4 Mark Mueller No No No
View Wed Mar 3 Becs Hodgetts No No Yes (2)
View Wed Mar 3 Chris Bilbrey No Yes (2) Yes (3)
View Tue Mar 2 Chris Bilbrey No Yes (2) Yes (5)

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Weather Observations
Station Date Time Temperature Relative Humidity Wind Speed Wind Direction Max Gust 24 Hr Snow
Wolf Creek Pass Fri Mar 5 5:00 AM 16 83 34 27 51 -

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