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)
|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|
|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)|
|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|