Looks like 2018 will go out with a bang. A winter storm warning is in effect until 2019 (midnight tonight).
As of 3 PM today we have accumulated ~12" of new snow near treeline. West and North winds are expected to drift snow. The snow is very low density (awesome pow!) and will be easily transported.
Wind slab and storm slab avalanche hazard is increasing. Natural avalanches are possible, human triggered avalanches probable on wind loaded and steep terrain. Easily induced small sloughing on 35+ degree terrain has been observed at Snowbowl.
Near and Above Treeline:Natural avalanches are possible, human triggered avalanches probable on wind loaded and steep terrain. Wind slabs and large accumulations may overload our weak/faceted early season snowpack, potentially creating larger more destructive avalanches.
We recommend staying away from steep avalanche prone terrain until the snowpack has time to adjust. Should you go, cautious route finding, conservative decision making and snowpack evaluation will be essential.
Remember most slab avalanches occur during a storm or within 48 hours of accumulation.
Below Treeline:The new accumulation is very welcome and will help our low tide. Expect rocks and logs to be hidden under the new coverage.
Natural avalanches possible, human triggered avalanches probable on wind loaded and steep terrain.
Keep an eye on the ASBTP weather station. Speeds between 17 and 25 mph are ideal for transporting snow and creating wind slabs.
Cold temperatures will inhibit bonding between layers of snow. This problem may last a while into the new year.
Due to cold temperatures, new snow bonding to old snow may be an issue.
The bullseye slope angle for avalanche activity is 38 degrees. Moderating slope angles to 30 degrees and less drastically reduces the likelihood of triggering an avalanche.
See our courses page for upcoming free courses, including a FREE Introduction to Avalanches Seminar at Aspen Sports on January 3.
Backcountry permits are required for travel in the Kachina Peaks Wilderness and available at local USFS locations, as well as, at the Agassiz Lodge on Saturday and Sunday 8:30 -11:30 a.m.
For information on uphill travel within the Arizona Snowbowl ski area, please refer to www.flagstaffuphill.com and https://www.snowbowl.ski/the-mountain/uphill-access/ for details. Access to the Kachina Peaks Wilderness is available from the lower lots at Snowbowl via the Humphreys Trail and Kachina Trail.
As of noon today, December 31st, Snowbowl reports 10" of new snow and SNOTEL reports 6" of new.
From NWS Flagstaff
...WINTER STORM WARNING REMAINS IN EFFECT UNTIL MIDNIGHT TONIGHT...
Heavy snow occurring. Plan on difficult travel conditions, including during the evening commute. Additional snow accumulations of 3 to 5 inches, with localized amounts up to 9 inches over the highest elevations, are expected.