Archived Hatcher Pass, AK Advisory Avalanche Advisory for January 2, 2016 at 11:51 am This avalanche advisory expires in 24 hours from posting BOTTOM LINE CONSIDERABLE AVALANCHE HAZARD at upper elevations (3500+) for WIND SLABS 6? to up to a foot thick at upper elevations on leeward aspects, generally North to West, and on slopes 35° and steeper. Sensitivity will be touchy today with human triggered wind slab avalanches likely, but quickly moving to stubborn tomorrow as these slabs stabilize. The distribution of soft, new wind slabs will be patchy and pocketed and the size of these avalanches will be on the small to medium side. Careful snowpack evaluation, cautious route finding, and conservative decision-making are essential. MODERATE AVALANCHE HAZARD at mid (2500'-3500') to upper (3500’+) elevations for PERSISTENT SLABS AND CORNICE HAZARDS. Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern. Human triggered avalanches possible, natural avalanches unlikely. Small avalanches in specific areas; or large avalanches in isolated areas. Avoid wind loaded and cross loaded areas, generally North to West aspects or anywhere where snow has been wind loaded and/or where winds have built stiff, hard slabs this week. Be especially careful in and around gaps and passes. Today’s avalanche hazard has low probability, but HIGH CONSEQUENCE. If you choose to travel in the backcountry this weekend, choose scoured vs. loaded slopes, stay out of the runnout of loaded slopes and features, and avoid any heavily wind loaded areas. Good skiing/riding conditions exist in small, patchy zones at mid to lower elevations where some wind protection exists. Poor skiing/riding conditions and increased avalanche hazard exists at upper elevations where almost every snow particle was hammered by the wind. LOW AVALANCHE HAZARD at low elevations (below 2500') and out of the runnout of significant hazards from mid and upper elevations. Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features. Use extra caution around wind loaded terrain traps. RECENT ACTIVITY and CONDITIONS No reported avalanches at HP this week, however visibility has been very limited. The powder honeymoon is over. Strong winds this week have redistributed Hatcher Pass’s entire snowpack. Almost every ridgeline and raised feature has been scoured, many to the ground, and all the snow has been piled into gulleys and leeward terrain features as hard slabs. Sastrugi is widespread, and a patchwork of exposed, scoured, older rain crust over sandy facets litters the landscape. If you are looking for variable snow conditions, Hatcher’s got it. On a good note, small protected areas of warm, rounded, fast snow exists. Strong SE winds and moving snow dominated this weeks weather with max gusts at 4500' of 56 mph on December 28th and 60 mph on December 30th. The average wind speed for the week at 4500' was 32 mph. Overnight winds at 4500' averaged ESE 18.5 mph, gusting to 39 mph. Temperatures were mild with a low of 18°F and a high of 28°F at 4500'. A minimum temp of 19°F and a maximum of 34°F was reported at the Independence Mine Snotel (3500'). Overnight temperatures on the Marmot Weather Station at 4500' reached a high of 27.5°F and dropped to a current temperature of 23°F at 6:00am. Independence Mine Snotel (3500') reported a high of 35°F at 9pm yesterday, currently 29°F at 6:00am. Approximately 4? of new snow accumulated this week at Independence Mine Snotel (3500'), with an additional 2? overnight. The Gold Chord weather station (4050') is reporting 1? of new snow overnight. AVALANCHE PROBLEM 1 Through the week a few intervals of light snow accumulation brought an approximate total of 6? of new snow at the Gold Chord Weather Station (4050'). Winds have continued to move the new snow as well as some older snow. Fresh, soft wind slabs exist 6? to possibly 1 foot deep at upper elevations in specific leeward locations, generally North to West aspects, mostly at ridgeline and on some cross-loaded features. These slabs will be sensitive to trigger today on slopes 35° and steeper, but will quickly stabilize through the weekend, and will be generally small in scale. Newly formed wind slabs are breaking on a new wind-blown snow interface and the old snow surfaces. Use caution around any leeward aspect as even a smaller wind slab could carry you into terrain traps and hazards. AVALANCHE PROBLEM 2 The persistent slab problem still lingers. Wind loaded areas, on generally North to West aspects, have thick, hard and soft slabs ranging from 6? to up to 3 feet thick sitting over persistent, weaker snow. The persistent, weaker snow has begun to round with mild temperatures improving the bond between slabs and the persistent grains. This is good news for the long-term. However, for this weekend, poor structure is still present which has been brought closer to the tipping point by this week’s new, heavy wind loads. Expect these slabs to be stubborn to trigger, and know you are dealing with a HIGH CONSEQUENCE avalanche problem. Hard slabs may break further back on terrain features than you may expect. Give them a wide berth. They may not be triggered by the first skier/rider and will be very unpredictable. These types of avalanches could easily injure or kill you. Avoid any area that has been recently wind loaded. Identifying these locations will be easy, IF you have good visibility. Cloudy, flat light conditions will make identifying this avalanche problem difficult. AVALANCHE PROBLEM 3 While this week’s winds were busy reshaping Hatcher Pass’s snowpack, they were also building bigger cornices on almost every ridgeline. These freshly built cornices are unpredictable, and in some cases have reached monstrous proportions, teetering on the brink of failure. Be especially cautious approaching any upper elevation ridgeline. Scout your play zones carefully to avoid being under the fire or runnout of large cornices. Recognize that a cornice failure of this size could trigger a large avalanche, or the size of the cornice chucks alone could be big enough to injure or kill you. One particular cornice was observed on Friday along the Ray Wallace chutes teetering on a rock outcrop which appears to be the size of a small school bus. Heads up. TREND The avalanche hazard will remain steady through the weekend for persistent wind slabs and cornices. The wind slab hazard will likely improve overnight and into Sunday.