Flagstaff, Arizona - Backcountry of The San Francisco Peaks and Kachina Peaks Wilderness
Format and Limitations Statement
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Skiable terrain is mostly on wind protected slopes and northerly aspects. Persistent weak layers continue to plague our thin snowpack . See AZ snow pit data at snowpilot.org
- link also under the snowpack menu.
Human triggered avalanches may still be possible in isolated steep terrain - mainly on northern, northeastern and eastern aspects near and above treeline. These will mostly be small to medium sized, due to highly variable winds, some of which were strong enough to cause more scouring and sublimation than lee slope loading. Pockets of wind slab overlaying previously developed basal facets is the most likely slab/weak layer combination. The specific location of hazards is spatially variable. Wind slabs and cross loaded slopes should be carefully evaluated before choosing to descend. Safer options in the trees may be advisable. Warm midday temperatures could increase the probability of triggering a persistent weak slab.
Significant cold (below freezing) temperature gradients are present in the mostly thin snowpack, exacerbating facet formation and weakening the snowpack, especially on northerly aspects.
Above treeline wind events have loaded leeward slopes near ridge lines in the last week, creating wind slabs that have demonstrated varying levels of stability. These windslabs may prove reactive if persistent weak layers on northerly aspects are weak enough to fail in localized loaded terrain.
With more snow and wind in the forecast, new wind slabs may form on leeward aspects.
With ~37" (94 cm) undisturbed settled snow depth at 10800', NW aspect, rocks and logs remain primary hazards.
Most northerly aspects will have the best coverage with measured depths at 10,000' ranging from 22 to- 50" (56 cm to 127 cm), while south facing slopes range from no snow to 28" (71 cm) in favored locations near treeline. Melt freeze crusts are developing on sun exposed slopes.
The snow depth is highly variable due to wind transport and sun affect, aspect dependent.
The thin snowpack continues to create basal facets and depth hoar, especially on northerly aspects. Cohesive slabs above these weak facets are potential areas of instability on all aspects.
Be cautious of previously loaded terrain - old wind slabs on northerly/shaded slopes may have persistent weak bonds.
Warm midday temperatures may increase the probability of triggering a persistent slab.
The problem is not widespread. So keep your guard up especially in isolated pockets.
With warm air temperatures, the snow surface will become moist. Watch for signs of decreasing stability, such as small point release avalanches running from rocky terrain or roller-balls on steep sunny slopes. An unsupportable wet snowpack, exhibiting slush characteristics means it is time to move to lower angle or cooler slopes. Spring officially begins March 20, equinox, warming slopes with a higher angle of insolation.