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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)

See more photos & videos

Avalanche Observations
Report Date # Elevation Aspect Type Trigger SizeR SizeD
View Fri Feb 23 - >TL N HS N / u R3 D3
View Fri Feb 23 - >TL NE HS N / u R3 D3
View Fri Feb 23 - >TL N HS N / u R3 D2.5
View Fri Feb 23 - TL N HS N / u R2 D2
View Fri Feb 23 - >TL N HS N R1 D1
View Fri Feb 23 - >TL N HS N R2 D2

See All Avalanche Observations

Field Reports
Report Date Observer Snowpack Obs Avalanches Media
View Sat Feb 24 Jay Godson No No Yes (2)
View Sat Feb 24 Jeff Davis Yes (1) Yes (4) Yes (5)
View Sat Feb 24 Kreston Rohrig Yes (2) No Yes (3)
View Sat Feb 24 Kyle Lefkoff No No No
View Fri Feb 23 Mark Mueller No No No
View Fri Feb 23 Ann Mellick Jeff Davis Yes (1) No Yes (2)
View Fri Feb 23 Roger Coit No No Yes (1)
View Fri Feb 23 blase reardon No No No
View Fri Feb 23 Jason Konigsberg No Yes (1) Yes (2)
View Fri Feb 23 Kreston Rohrig No No Yes (2)

See All Field Reports

Weather Observations
Station Date Time Temperature Relative Humidity Wind Speed Wind Direction Max Gust 24 Hr Snow
Bear Lake Sun Feb 25 12:00 AM 10 - - - - 1.0
Steamboat Lake State Park Sun Feb 25 12:00 AM 9 91 1 32 4 1.4
Bottle Peak Sun Feb 25 12:00 AM -1 87 22 258 25 -
Berthoud Pass Sun Feb 25 12:00 AM -3 80 15 256 36 -
Cameron Pass Sun Feb 25 12:00 AM -1 84 10 244 22 -
Grand Mesa - Skyway Point Sun Feb 25 12:00 AM 4 89 3 218 11 2.0
Kendall Mt Sun Feb 25 12:00 AM -5 85 24 201 42 -
Loveland Pass Sun Feb 25 12:00 AM -3 82 19 249 35 -
Molas Pass Sun Feb 25 12:00 AM 5 90 5 207 14 -
Putney Sun Feb 25 12:00 AM 0 85 25 251 43 -
Swamp Angel Sun Feb 25 12:00 AM 6 77 2 219 16 0.1
Wolf Creek Pass Sun Feb 25 12:00 AM 0 85 18 234 30 -
Monarch Pass (050e200) Sun Feb 25 12:44 AM 1 83 4 160 9 -
Columbus Basin Sun Feb 25 12:00 AM 9 - - - - -
Hayden Pass Sun Feb 25 12:00 AM 6 - - - - -
Lizard Head Pass Sat Feb 24 11:00 PM 11 - - - - 1.0
Mc Clure Pass Sun Feb 25 12:00 AM 14 - - - - -
Medano Pass Sun Feb 25 12:00 AM 17 - - - - 1.0
Mesa Lakes Sun Feb 25 12:00 AM 8 - - - - -
Ripple Creek Sun Feb 25 12:00 AM 5 - - - - -
South Colony Sat Feb 24 11:00 PM 10 - - - - -
Slumgullion Sun Feb 25 12:00 AM 5 - - - - -
Schofield Pass Sun Feb 25 12:00 AM 7 - - - - -
Storm Peak Observatory Sat Feb 24 11:55 PM -1 91 16 290 20 -
Taylor Park Sat Feb 24 11:57 PM 3 81 1 183 4 -
Wolf Creek Summit Sun Feb 25 12:00 AM 8 - - - - -
Zirkel Sun Feb 25 12:00 AM 8 - - - - 1.0

See All Weather Observations