Current new snowfall is 14" at 11,000'. Residual snow from early October has turned to facets at higher elevations on northerly aspects, creating a very weak layer onto which new storm and windblown snow will rest. Other aspects and elevations with no snow cover prior to this storm cycle are barely covered and hazardous to navigate on skis or boards. Avalanche activity may be localized due to wind loading along ridgelines or cross loaded terrain features.
The sequence of two storms this weekend is predicted to deposit 12-24 inches of new snow, with southwest winds loading northwest and east aspects. If precipitation and winds meet or exceed predicted levels, natural avalanches will be possible, and skier triggered avalanches are likely on steep terrain where old snow underlies the new. Stability will deteriorate as the second storm impacts the area Saturday. Size and distribution of avalanches will be highly variable based on the distribution of old faceted snow, and the depth and cohesiveness of the new snow on top.
Starting zones will generally be at and above treeline on cool north facing slopes where storm winds have loaded new snow on top of old facets. Potential avalanche sizes will be dependent on new snow depth and wind re-distribution. Moderate to large avalanches may be possible where faceted snow remains in the starting zones, such as Abineau Canyon and North Core Ridge. Expect early season obstacles and hazards in the thin snowpack...
On lower elevation slopes, baseless new snow will create obstacle hazards rather than avalanche hazards. Early season conditions will exist until more snow arrives and new snow settles and gains density. As the week progresses, changing weather might create a corresponding increase in the avalanche danger, as well as, change the type of avalanche problems you may encounter.
Near and Above Treeline:Expect new and windblown snow sitting on top of old facets. Signs of instability may include "whumphing" and cracking of the snow under your skis or snowboard. If such signs are experienced, stay clear of slopes exceeding 35 degrees and report observations on our website. Early season skiing and riding can be particularly dangerous as overzealous enthusiasm leads to poor decision making.
Below Treeline:Safe backcountry travel may be challenging due to the shallow baseless snowpack at lower elevations. Until the snowpack fills in, hidden logs and rocks are significant hazards. Despite new snow it is still relatively thin out there. North and easterly slopes above 10,000 feet will be your best bet for sufficient coverage to ski/board.
Storm slab avalanches, of medium to large size are possible depending on the amount of snow loading on old facets at high elevations.
If predicted southwesterly and westerly winds materialize, wind slab avalanches will be possible on high elevation areas on lee facing slopes (NE to E) where slabs may develop on old facets at high elevation.
Looking into the future, with more snow accumulation on tap, instability may remain where snow is loaded on top of old facets at high elevation. Each successive storm may revitalize this instability.
The current storm total of 14" has exceeded all snowfall events of last season...let's hope this trend continues!
Backcountry Permits are required for travel in the Kachina Peaks Wilderness and available at local USFS locations, as well as the Agassiz Lodge on Saturday and Sundays 9 -12 a.m. after the Agassiz Chairlift opens in December.
Uphill travel on terrain within the Arizona Snowbowl ski area is still closed. Please refer to flagstaffuphill.com and snowbowl.ski for details.
FREE AVALANCHE AWARENESS SEMINAR: Wednesday December 5, 6:00 pm, 911 Sawmill Rd, Leaf Auditorium.
Updated Friday November 30th at 1400
Our false start of winter in early October was followed by a month and a half of drought. Most of the 12 to 20 inches of snow that blanketed the Peaks above 10,800 feet has disappeared. The exceptions are up high (above 11,000 feet) and on shady north and northwest aspects where shallow snow remains. This snow has reacted to cold, clear conditions progressively turning to poorly bonded facets.
Now it appears the pattern may be changing and perhaps winter has finally arrived for real. A significant low pressure system is currently bearing down on us (at the time of publication) bringing anticipated snowfall to the high country above 5500-6000 feet. Snow totals are expected to reach between 12 and 20 inches at 10,800 feet. Storm winds will be out of the southwest and west 29-34 mph, gusting to as high as 49 mph; the perfect velocities for moving snow and loading up leeward aspects. A second storm on Saturday and Sunday will be colder and less moist. Snowline is expected to drop to approximately 4,000 feet adding another 6-12 inches of new snow at high elevations. Cold air will follow the second storm’s exit with gradually warming conditions during the week. A third storm appears to be on the distant horizon. It is too early for any certainty on precise timing of impact, but possibly arriving by the end of next week.
On the afternoon of November 30th, the Inner Basin SNOTEL site Snowslide reported a snow depth of 9 inches (23 cm) at 9,730 feet, and Arizona Snowbowl reported a settled base of 14 inches (36 cm) at 10,800 feet. So far this winter, 23 inches (58 cm) of snow have fallen at the mid-mountain study site. Since November 23rd, SNOTEL temperatures have ranged between 47° F on November 27 and 15° F on November 25th. For the same period, the AZ Snowbowl Top Patrol Station (ASBTP, 11,555 feet) the temperature ranged between 38° F on November 27 and 15° F on November 23rd.