• Backcountry Avalanche Forecast
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Wed, Nov 22, 2017 at 6:48 AM
Issued by: Brian Lazar

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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.
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

We continue to receive reports of avalanches breaking into old, weak snow. Combine this with widespread shooting cracks and large thunderous collapses, and we have plenty of good evidence that dangerous avalanche conditions exist on north and east-facing slopes at higher elevations. The most suspect slopes now have freshly form wind-drifted slabs from the 1 to 4 inches of new snowfall, stacked on top of older early season snow. The slopes with the best coverage are also the slopes where you're most likely to trigger an avalanche. You can trigger avalanches from a distance and from below, so give this terrain a wide buffer to address the unpredictability. 

We now have slabs 1 to 2 feet thick on east-facing slopes, and you might be able to trigger an avalanches in just the freshly drifted snow even in areas that don't harbor more deeply buried weak layers. Drum-like or hollow sounds underfoot are signs of this problem. You can reduce your risk by avoiding slopes where you observe active wind loading.

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, 7:35 AM
@CAIC: MOD(L2) Near & Above TL Look for cracking collapsing & previous Avys Limit risk by avoiding NW->NE->E NR/ATL Nov 21, 7:32 AM

Avalanche Problem

 
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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

 
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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

 
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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) 25 to 30 40 to 45 25 to 30
Wind Speed (mph) 15 to 25 15-25 G50 20 to 30
Wind Direction WNW WNW W
Sky Cover Mostly Clear Partly Cloudy Partly Cloudy
Snow (in) 0 0 0

Archived Forecasts

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Wed, Nov 22, 2017 at 7:22 AM
Issued by: Brian Lazar Statewide Weather Forecast  

We got just enough snow and wind over the last day or two to complicate avalanche conditions. The 1 to 4 inches of new snow and strong west and northwest winds created fresh wind-drifted slabs around a foot thick. On high-elevation north and east-facing slopes this fresh slab is stacked on top of the the Persistent Slab avalanche problem that formed earlier. This incremental loading will make triggering an avalanche breaking into deeper weak layers a bit easier than a day or two ago. 

We also need to consider south east aspects as well.  On these slopes there are just wind-drifted slabs without the underlying persistent weak layers, but even triggering a Wind Slab avalanche a foot thick could be enough to injure you or bury you in a terrain trap. 

The snow that fell in October and didn't melt off gradually transitioned into weak basal facets and crust-facet combinations. The saving grace is that the early season snow did melt off in most places, so this worrisome snowpack foundation isn't widespread. It is confined to near and above treeline slopes that face northwest to north to east. But, on these slopes you can easily trigger an avalanche. The storm event from last week provided the first test of the weak foundation, and it did not hold up well. Anywhere the new storm snow fell on a preexisting snowpack, we saw evidence of instability: avalanches, shooting cracks, and propagating snowpack tests. 

The saving grace is that the early season snow did melt off in most places, so this worrisome snowpack foundation isn't widespread. It is confined to near and above treeline slopes that face northwest to north to east. But, on these slopes you can easily trigger an avalanche. The storm event from last week provided the first test of the weak foundation, and it did not hold up well. Anywhere the new storm snow fell on a preexisting snowpack, we saw evidence of instability: avalanches, shooting cracks, and propagating snowpack tests. 

The danger is MODERATE (Level 2) because the suspect slopes are not widespread, natural avalanches are unlikely,  and due to lack of snow coverage, very large avalanches are also unlikely. But, the most suspect slopes are also the most attractive for recreating. We're going to be lured to slopes with deeper coverage.  Despite all the rocks, shrubs, and bare ground poking through the thin snow coverage in most places, it is avalanche season up high.

Be cautious near, on, or below, any slope steeper than about 30 degrees that looks like rocks and shrubs are buried and no longer visible. This near miss in the Aspen zone is exactly the type of event we want to avoid. You can trigger avalanches from below or from a distance. Give yourself a wide buffer around potential avalanche terrain to account for this unpredictability.  The Persistent Slab avalanche problem will be with us for a while. 

 


  • Remotely triggered cracking. Was able to safely ski cut the crack but it wouldn't move. (full)
  • Pit was located 200m downslope from where the remotely triggered cracking occured. (full)
  • Looking back at the slope that collapsed. If this was a steeper slope it would have resulted in a large dangerous avalanche. (full)
  • East aspect at 12,200ft. Notice the pencil hard crust in the misssle of the snowpack. (full)

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Avalanche Observations
Report Date # Elevation Aspect Type Trigger SizeR SizeD
View Sun Nov 19 - >TL E U N R2 D2
View Sun Nov 19 - >TL E SS N R2 D1.5
View Sun Nov 19 - >TL E HS N R2 D1
View Sun Nov 19 - >TL SE HS N R2 D1.5

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Field Reports
Report Date Observer Snowpack Obs Avalanches Media
View Tue Nov 21 Ryo Sueda No Yes (1) Yes (1)
View Mon Nov 20 Mike Cooperstein No No No
View Mon Nov 20 Carter Spencer No No Yes (2)
View Mon Nov 20 - No No No
View Sun Nov 19 Wil Rickards No No Yes (2)
View Sun Nov 19 Nick Barlow No Yes (1) No
View Sun Nov 19 Ryan Zarter No Yes (2) Yes (2)
View Sun Nov 19 John Gibbons No No Yes (1)
View Sun Nov 19 chase courington No No Yes (1)

See All Field Reports

Weather Observations
Station Date Time Temperature Relative Humidity Wind Speed Wind Direction Max Gust 24 Hr Snow
Bear Lake Wed Nov 22 7:00 PM 39 - - - - -
Bottle Peak Wed Nov 22 6:50 PM 31 100 34 279 39 -
Berthoud Pass Wed Nov 22 7:00 PM 29 96 23 320 47 -
Cameron Pass Wed Nov 22 7:00 PM 31 98 13 243 25 0.4
Joe Wright Wed Nov 22 7:00 PM 37 - - - - -
Loveland Basin Wed Nov 22 7:00 PM 33 - - - - -
Lake Eldora Wed Nov 22 7:00 PM 40 - - - - -

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