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Mon, Dec 6, 2021 at 7:17 AM
Issued by: Jeremy Yanko

Monday

 

Tuesday

Low (1) Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.   Moderate (2) Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully.
Low (1) Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.   Moderate (2) Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully.
Low (1) Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.   Low (1) Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.
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Summary

Today, you may be able to trigger a small slide on very steep, northerly-facing slopes above treeline. Here, you may find wind-stiffened snow that appears smooth and rounded in gully features and below ridgelines. Lower-angled, wind sheltered terrain or slopes with limited snow cover offer safer traveling options. The first, in a series of storms is slated to begin tonight and add a new load to our weak snowpack, potentially increasing the danger starting tomorrow. 

 
Weather Forecast for 11,000ft Issued Mon, Dec 6, 2021 at 12:27 PM by Mike Cooperstein Statewide Weather Forecast
  Monday Night Tuesday Tuesday Night
Temperature (ºF) 20 to 25 28 to 33 16 to 21
Wind Speed (mph) 12 to 24 10 to 20 8 to 18
Wind Direction WSW WSW W
Sky Cover Mostly Cloudy Mostly Cloudy Partly Cloudy
Snow (in) 0 to 2 0 to 2 0

Archived Forecasts

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Mon, Dec 6, 2021 at 7:43 AM
Issued by: Jeremy Yanko Statewide Weather Forecast  

A highly anticipated change is on the horizon as weather models continue to advertise a significant pattern shift and snowfall to begin tonight. By Tuesday morning, if the forecast verifies, we expect avalanche conditions to change and danger to ramp up more by the end of the week. The amount of new snow received and wind accompanied with the two storms forecasted will keep us on our toes each day as this evolves. The snowpack throughout the Southern Mountains is queued up for potentially the first real tolerance test of the season as November was not a big moisture producer. 

The majority of our snowpack, accumulated in the month of October is now faceted and weak at the surface and also within the pack on northerly-facing slopes. Above treeline, east and west aspects offer firm- crusted surfaces overlying weak-faceted snow and older crust layers below. Time will tell, but it will likely not take much of a new load to produce avalanches that step deeper into the foundational snowpack.  

In addition, the snow on north-facing slopes, near and below treeline is also very weak. Those slopes hold loose, cohesionless snow from the surface to the ground. This lack of structure becomes more problematic on steep rolls or creek banks where the weak surface facets are likely to sluff from the weight of a rider and will gain mass while moving downhill. We expect these facet sluffs to remain small in size, but if caught, the consequences could yield a rough ride through shallowly buried obstacles. 

Although the start to the season appears bleak, keep in mind that bare ground or patchy snow-covered terrain provides a clean slate. Those slopes will not have old snow layers lurking below and should offer safer options as new snowfall is added. Patience and careful terrain selection will be crucial moving forward this week and awhile beyond.  

 


  • General snow cover looking west across Cascade Creek. Grizzly Peak is on the right edge of the photo and Sliderock Ridge is on the left edge of the photo. South San Juan. November 26, 2021. (full)
  • Once we isolated the column and compensated the tensile strength of the slab, we observed propagating results and sudden planar fractures in stability test where a thick, wind-drifted slab rest above weaker snow. We did not observe any other signs of instability on this slope. On the margins of the slab, the snowpack was shallower and mostly faceted. South San Juan. November 26, 2021. (full)
  • Snowpit on a north aspect near treeline. South San Juan. December 1, 2021. (full)
  • Evidence of scouring and drifting on north-facing alpine terrain. Some drifts were around 12 inches deep. South San Juan. November 24, 2021. (full)

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Weather Observations
Station Date Time Temperature Relative Humidity Wind Speed Wind Direction Max Gust 24 Hr Snow
Wolf Creek Pass Mon Dec 6 7:00 PM 20 51 28 238 43 -

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