• Backcountry Avalanche Forecast
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Wed, Nov 22, 2017 at 6:38 AM
Issued by: blase reardon

Today

 

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.
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.
  Danger Scale

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Summary

Strong westerly and northwesterly winds have drifted snow onto lee slopes, complicating conditions at upper elevations. Avoid steep slopes with newly-formed drifts on northeast, east and southeast slopes above treeline. Expect isolated slopes with this danger in near-treeline terrain.

On shaded slopes, this danger may may overlap with a Persistent Slab avalanche problem, increasing the likelihood and potential size of triggering slides that break near the ground. This danger exists wherever recent storm snow buried weak, early-season snow. It's most widespread on cold, northerly slopes above about 10,500 feet. It may also be lurking on other aspects or at lower elevations where shade from trees or rocks preserved snow that fell early this season. 

Those slopes are the same slopes that can be most attractive for early season riding, because the snowpack is deeper. Avoid being on or under slopes steeper than about 35 degrees if you see shooting cracks or feel any whumpfing collpases. Check your safety equipment before you arrive at a trailhead and review safe riding protocols with your partners.

The Friends of CAIC are hosting the 10th Annual CAIC Benefit Bash on December 2, 2017 in Breckenridge The funds from this event go to support the CAIC and these backcountry forecasts. It’s an event not to miss. For more information and to purchase tickets visit: https://adecadedeep.eventbrite.com.

 

Recent Tweets

@CAIC: Av season! Poss 2 trigger avs that break nr ground NW-N-SE slopes, esp those w fresh wind drifts. MOD(Level 2) Nov 22, 7:21 AM
@CAIC: Avalanche season up high. B alert 4 cracks whumpfs fresh drifts on/below slopes >35 deg. MOD(L2) N/ATL. Nov 21, 8:07 AM

Avalanche Problem

 
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Above Treeline
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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
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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.

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.

Weather Forecast for 11,000ft Issued Wed, Nov 22, 2017 at 11:51 AM by Brian Lazar Statewide Weather Forecast
  Wednesday Night Thursday Thursday Night
Temperature (ºF) 27 to 32 42 to 47 28 to 33
Wind Speed (mph) 7 to 17 5 to 15 10 to 20
Wind Direction NW WNW W
Sky Cover Partly Cloudy Mostly Clear Partly Cloudy
Snow (in) 0 0 0

Archived Forecasts

  • Select Forecast: Valid

Wed, Nov 22, 2017 at 7:10 AM
Issued by: blase reardon Statewide Weather Forecast  

In the past 24 hours, winds have averaged 15-25 mph with gusts to 50 mph at near- and above-treeline weather stations. These strong winds have been blowing from the west and northwest, loading easterly slopes near ridgelines and on the lee sides of prominent terrain features. That’s complicated the avalanche picture for today and tomorrow. 

On some slopes, these freshly-formed wind slabs can be a danger in their own right. That’s mostly steep, east- and southeast-facing slopes above treeline, where the drifted snow fell on recent snow instead of bare ground. Similar conditions may exist on isolated northeast slopes and on the same aspects near-treeline. In this terrain, you can trigger slabs of drifted snow one to two feet thick. Avoid slopes steeper than about 35 degrees where you see dunes or find dense deposits of cakey, drifted snow.

On northeasterly slopes, the Wind Slab avalanche problem may overlap with a more widespread Persistent Slab avalanche problem. Where the winds deposited snow on slopes that harbor old, collapsible snow near the ground, the drifted snow is increasing the likelihood and potential size of triggered avalanches. The layer of old, faceted snow was the failure plane for a spate of natural and triggered avalanches when it was buried by heavy snowfall Friday. In some cases, the crowns ran long distances and connected across terrain features. People reported some slopes failing remotely, resulting in one very close call. In that incident, the two riders triggered a slope above them, but safe travel protocols - riding one at a time - kept the avalanche from having far more serious consequences. 

The danger posed by the Persistent Slab avalanche problem will linger, especially on slopes where it is exacerbated by the wind-loading of the past 24 hours. Be on the lookout for steep slopes where the snowpack is deep enough and continuous enough to cover ground features. Carry avalanche rescue gear, rely on safe travel protocols, and look for obvious signs of danger, like collapses and shooting cracks. Follow those practices even on trips up closed ski areas, where there’s been no mitigation on slopes that are steep enough to slide. 

Thanks to everyone who's contributed observations so far this winter. Special thanks to people who reported unintentionally triggered avalanches and/ or close calls. These are invaluable to other backcountry travelers, and they help us to confirm or fine-tune our forecasts. If you're out and about, please let us know what you see. It doesn't need to be dramatic or technical; just report some basics information about where you went, what kind of slopes you rode, and what the snow was like. Alerting us to any recent or triggered avalanches can be especially helpful. 


  • The site of a very close call above Ashcroft. Two snowboarders skinned up the lower-angled slopes to looker's left, then descended the gully one at a time. They triggered a slab above the them on looker's right. It carried one rider down the gullly and left him partially buried. 11-18-17 (full)
  • Crowns from natural avalanches on northerly slopes above upper Mud Gulch/ The Fridge. The crowns connect across terrain features. 11-18-17 (full)

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Avalanche Observations
No relevant backcountry observations found for this forecast

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Field Reports
Report Date Observer Snowpack Obs Avalanches Media
View Wed Nov 22 blase reardon No No No
View Mon Nov 20 - No No No

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Weather Observations
Station Date Time Temperature Relative Humidity Wind Speed Wind Direction Max Gust 24 Hr Snow
Chapman Tunnel Wed Nov 22 7:00 PM 35 - - - - -
Independence Pass Wed Nov 22 7:00 PM 36 - - - - -
Ivanhoe Wed Nov 22 7:00 PM 35 - - - - -
Sunlight Wed Nov 22 8:00 PM 34 86 5 350 - -
Mc Clure Pass Wed Nov 22 7:00 PM 42 - - - - -
Schofield Pass Wed Nov 22 7:00 PM 35 - - - - 1.0

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