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BOTTOM LINE:

Natural avalanches are very unlikely and human triggered avalanches are unlikely at mid and high elevations on all aspects. Natural avalanches are unlikely and human triggered avalanches are possible on south aspects at low elevation.

TREND:

Stable on most aspects.

Deteriorating stability on south aspects at low elevation during the heat of the day.

DISCUSSION:

The amount of tracks at Hatcher Pass right now could fool just about anyone into thinking a ski resort was nearby. The number of tracks and the absence of significant natural and human triggered avalanches shows the long withstanding stability trend we have endured over the past month. Conditions continue to range from windslab, to sun crust, to facet powder, and a mix of all of the above. Between 3/23 and 3/24 wind speed picked up enough to develop a wind crust/slab varying from 1-5″ thick on exposed north, east and west aspects. Wet loose point releases have been observed in greater numbers on south aspects at low elevation during the heat of the day.

Due to a cooler March, we have yet to see significant heating and a true “shed cycle” of the snowpack. Be warned, it is on the way. The stability of the snow and low energy has made us lazy by way of FACETS. (Familiarity, Acceptance, Consistency, Experts, Tracks, and Scarcity) These FACETS are heuristics that lead to poor decision and avalanche accidents. Being aware of them can keep you out of trouble. As the weather changes so must our perspective of the snowpack. New wet snow or rain and/or significant heating will dramatically change the structure and stability of the snowpack.

At this point our biggest concern lies on south aspects. Sun crusts and radiation crusts are growing in size and developing larger facets beneath the crusts. South aspects at low elevation are heating up enough for wet-loose point releases to become prime time. These avalanches are growing in size and number, and are large enough to throw you off your feet or week a knee. As the sun beats its blazing rays on the slopes wet-loose avalanches will become more likely.

The large gaping cornice crevasses continue to grow in size, weakening bonds to their slopes, and preparing for detachment as the sun’s radiation increases. Good hazard evaluation techniques should be used in conjunction with keeping a humble distance from the large cornice edge.  Cornices can be good stability indicators as they weaken, detach, and fall onto slopes beneath them. Watch to see if they trigger any sizable avalanches as they fall.

No dramatic changes have been observed on N,E, and W aspects. A new brittle wind slab 1-5″ thick exists on some north, northeast, and west aspects.  This wind slab varies in hardness and sits over large facets, however, the lack of energy in the snowpack has withheld key ingredients in the recipe for an avalanche. This slab is non-cohesive and brittle, however, the possibility of popping out a small slab exists on shallow faceted ridges, rollovers, and rocky zones, so choose lines wisely.

Paying attention to the rate of change as we blossom into spring will be tell tale of the avalanche cycles to come.

-Allie Barker

This advisory expires in 24 hours

BOTTOM LINE:

Natural avalanches are very unlikely and human triggered avalanches are unlikely at low elevations. At mid and high elevations natural avalanches are unlikely and human triggered avalanches are possible.

TREND:

Stable.

DISCUSSION:

Hatcher has experienced a long spell of beautiful sunny weather over the past 10 days. More tracks have been laid down than we have ever seen at Hatcher Pass. Conditions range from sun crust, to faceted recycled powder, to thin brittle wind crust. A short spell of easterly 30+ mph winds on 3/14 (recorded at both weather stations) lasted 24 hours, leaving westerly slopes with a new wind slab, covering last weekends tracks, and cross loading some north and south aspects.

Wet loose point releases were observed today on  multiple south aspects. You are  more likely to get caught in a wet loose avalanche on southerly aspects with a higher angle of incidence in conjunction with rocky starting zones that heat up rapidly during the day.

While our pale Alaskan ghostly figures are being torched by the sun, the snowpack is also starting to show sun effects. Our returning midnight sun has assisted in the formation of variable sun crusts on south and some east and west aspects ranging from 1-4″, in addition to firnspeigel on the snow surface. The crust, which sits on top of buried near surface facets, could act as a weak layer under a new dump of higher density wet snow and potentially trigger larger and more dangerous wet loose point release avalanches.

Multiple cornice crevasses were observed today at mid-high elevation. These cornices are large and pose great danger if traveling too close to the edge on ridgelines above leeward slopes. If traveling on ridgelines stay 20′ or more away from the cornice edge. These cornices are deteriorating.  Falling into the crevasses/holes and/or taking an unpleasant ride down a leeward slope from a cornice collapse are real consequences.Photo

Two new slab avalanches (SS-N[y?]-R3-D2.5-I) were observed today at high elevation (5000′) on a West aspect. Photo. Two other slab avalanches (up to a week old) of smaller size were still visible on the same aspect and elevation. The most recent avalanches most likely occurred after the 3/14 wind event. The fracture characteristics of the slab appear to have failed on surface hoar or buried near surface facets in the new snow/old snow interface.  These avalanches remind us that although not widespread, instabilities do exist in the upper layers of the snowpack on west cross-loaded and loaded aspects at upper elevations.

-Allie Barker