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Monday, November 20, 2017 at 6:33 AM Issued by: Nick Barlow  

Last Friday’s quick-hitting storm system came in with a punch. The Northern Mountains picked up eight to fourteen inches of new snow, while some portions of the Central Mountains saw more than twenty inches. Snow accumulations were less in the Southern Mountains, where two to eight inches fell. Vigorous southwest winds accompanied the storm, efficiently drifting the new snow into sensitive surface slabs. This rapid new load upon our weak, early-season snowpack is a dangerous combination.

Reports of recent avalanches in the backcountry continue to filter into the CAIC, including human triggered, remote triggered, and natural avalanches. There was a close call on Saturday near Aspen, involving a remote-triggered avalanche and partial burial of a snowboarder. Each avalanche report varies in specific details, but they all share many of the same characteristics.

Since October, most reported avalanches in the backcountry occurred on northwest through northeast to east-facing slopes near and above treeline. In the Northern and Central Mountains, the snowpack on these aspects may be two to four feet deep. Numerous recent reports of collapsing, shooting cracks, and remote-triggered avalanches suggest the presence of dangerous persistent weak layers. With poor snowpack structure observed statewide, including a CAIC Forecaster report Saturday near Wolf Creek Pass, the recent uptick in avalanche activity is not overly surprising. The Southern Mountains may lag slightly behind, but the Colorado backcountry as a whole is starting to form a concerning continuum.  

The Northern Mountains will see a few inches of new snow Monday night, while westerly winds ramp up for all zones. With ample snow available in windward fetches, slab building will continue on lee-facing slopes at higher elevations. Slabs in favored areas are growing thick, but much of the winter’s snowpack remains quite thin. Thin coverage also means that natural hazards like rocks and trees are lurking. Taking a ride in even a small avalanche could have severe consequences, as you are likely to be dragged across rocks and stumps. Additionally, recent remote triggers suggest danger from hanging snowfields above you, and unpredictable avalanche behavior in general. Steep, wind-affected slopes are not to be tangled with in this early-season environment. The same goes for any higher-angled terrain with more than about eight inches of new snow. 

We are issuing Zone Weather Forecasts at 6:00 AM and 1:00 PM daily. You can check current weather conditions on the Weather Stations page, and recent observations on the Field Reports page. Let us know what you see anything interesting out there by Submitting an Observation.

We will issue our first Zone Avalanche Forecasts on Tuesday November 21, 2017.

 
  • East aspect at 12,200ft. (full)
  • Conducting fieldwork around Vail Pass after 12 inches of snow fell in the last 24 hours. I triggered an avalanche and observed cracking and collapsing.
  • An avalanche remotely triggered near Vail Pass on 11/18. (full)
  • Crown and bed surface from a natural avalanche on northeast-facing slopes in Marble Bowl. 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 Mon Dec 11 Taigh McDonagh No No Yes (1)
View Mon Dec 11 Crested Butte Avalanche Center No No No
View Mon Dec 11 Crested Butte Avalanche Center No No Yes (1)
View Mon Dec 11 Ben Pritchett No No Yes (8)
View Mon Dec 11 Jason Konigsberg, Mike Cooperstein No No Yes (2)
View Mon Dec 11 Kreston Rohrig, Becs Hodgetts, Ryan Zarter No No Yes (1)
View Sun Dec 10 blase reardon Yes (1) No Yes (2)
View Sun Dec 10 Mike Cooperstein, Jason Konigsberg No No Yes (5)
View Sun Dec 10 Gabi Benel No No Yes (3)
View Sun Dec 10 Scott Messina No No Yes (1)

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Weather Observations
Station Date Time Temperature Relative Humidity Wind Speed Wind Direction Max Gust 24 Hr Snow
Bear Lake Tue Dec 12 8:00 AM 37 - - - - -
Steamboat Lake State Park Tue Dec 12 8:00 AM 9 96 1 277 3 1.2
Bottle Peak Tue Dec 12 7:50 AM 26 50 14 270 16 -
Berthoud Pass Tue Dec 12 8:00 AM 21 60 10 23 16 -
Cameron Pass Tue Dec 12 8:00 AM 26 46 6 195 11 0.6
Cottonwood Pass Tue Dec 12 8:00 AM 25 38 11 287 18 -
Grand Mesa - Skyway Point Tue Dec 12 8:00 AM 26 51 2 73 5 -
Kendall Mt Tue Dec 12 8:00 AM 28 19 10 323 13 -
Loveland Pass Tue Dec 12 8:00 AM 26 43 17 300 28 -
Molas Pass Tue Dec 12 8:00 AM 27 26 3 245 5 0.4
Putney Tue Dec 12 8:00 AM 34 13 6 2 9 -
Swamp Angel Tue Dec 12 8:00 AM 24 34 2 252 3 -
Wolf Creek Pass Tue Dec 12 8:00 AM 35 26 10 342 14 -
Monarch Pass (050e200) Tue Dec 12 8:34 AM 30 29 3 145 7 -
Columbus Basin Tue Dec 12 8:00 AM 31 - - - - -
Hayden Pass Tue Dec 12 8:00 AM 34 - - - - -
Lizard Head Pass Tue Dec 12 8:00 AM 21 - - - - 1.0
Mc Clure Pass Tue Dec 12 8:00 AM 32 - - - - -
Medano Pass Tue Dec 12 8:00 AM 27 - - - - -
Mesa Lakes Tue Dec 12 8:00 AM 27 - - - - -
Ripple Creek Tue Dec 12 8:00 AM 29 - - - - -
South Colony Tue Dec 12 7:00 AM 26 - - - - 1.0
Slumgullion Tue Dec 12 8:00 AM 31 - - - - 1.0
Schofield Pass Tue Dec 12 8:00 AM 23 - - - - -
Spud Mountain Tue Dec 12 7:00 AM 32 - - - - -
Storm Peak Observatory Tue Dec 12 7:30 AM 26 31 2 263 2 -
Taylor Park Tue Dec 12 7:57 AM 18 56 1 333 2 -
Wolf Creek Summit Tue Dec 12 8:00 AM 38 - - - - -
Zirkel Tue Dec 12 8:00 AM 25 - - - - 1.0

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