Avalanche Advisory for Saturday, January 25, 2014

This advisory expires at midnight. 

Tuckerman Ravine has Considerable, Moderate and Low avalanche danger. The Lip, Center Bowl, Chute, Left Gully and Hillman’s Highway have Considerable avalanche danger. Natural avalanches are possible and human triggered avalanches are likely. The Sluice and Lower Snowfields have Moderate avalanche danger. Natural avalanches are unlikely and human triggered avalanches are possible. Lobster Claw, Right Gully and the Little Headwall have Low avalanche danger. Natural and human triggered avalanches are unlikely except in isolated terrain features.

Huntington Ravine has Considerable and Moderate avalanche danger. Central, Pinnacle, Odell, South, and Escape Hatch have Considerable avalanche danger. Natural avalanches are possible and human triggered avalanches are likely. North, Damnation and Yale gullies have Moderate avalanche danger. Natural avalanches are unlikely and human triggered avalanches are possible. Careful snowpack evaluation, cautious route finding and conservative decision making is essential.

AVALANCHE PROBLEMS: Generally, we are starting out today with yesterday’s ratings. However, avalanche hazard will increase to our current ratings through the day. Persistent slabs will compete with wind slabs as our primary avalanche hazard today. A weak layer of facets lurks beneath older wind slabs in many areas which can crack and propagate into a medium size avalanche.  New snow on strong SW then S winds will build new wind slabs in north facing aspects and cross load other areas. This new loading will increase the chance of avalanches later today. Also, visibility will diminish through the day and hamper assessment of snow and terrain and complicate safe travel strategies.

WEATHER: A cold front is bringing snow to the mountains today. Winds from the southwest at 60-80 mph (97-130kph) will shift south and drop to the 50-70 mph (80-113kph) range with higher gusts. Not only will this wind velocity be sufficient to load snow into northerly aspects and crossload areas facing more to the east, it will hammer people on the Lion Head trail much harder than the usual northwesterlies do since there will be no windbreak from the summit cone. Projected wind speeds from this direction will make walking difficult above treeline all the way to the summit and be in your face descending the cone. The 2-4″ (5-10 cm) of new snow will fall through the day, increasing in intensity through the day.

SNOWPACK: The weak layer of sugary facets that has developed during the past week will continue as low air temperatures drive the faceting process. Deeper wind slabs from last Sunday and Monday’s strong westerly winds may be more reactive as the process reaches through the insulating layers of deeper snow to the less permeable melt-freeze crusts that support the growth of these cup shaped crystals. Steep slopes with these pockets may not require you to find a thin spot in these slabs to serve as a trigger and may react only to your weight. Be fast climbing today, but protect yourself on or beside otherwise easy steep snow climbing. Avoid these steep pockets and remember that the slabs are hard enough that they will support your weight but may be undermined by the persistent weak layer of facets. As additional snow adds to the load later today, it will become easier to your weight to tip the balance.

Please Remember:

  • Safe travel in avalanche terrain requires training and experience. This advisory is just one tool to help you make your own decisions in avalanche terrain. You control your own risk by choosing where, when, and how you travel.
  • Anticipate a changing avalanche danger when actual weather differs from the higher summits forecast.
  • For more information contact the Forest Service Snow Rangers, the AMC at the Pinkham Notch Visitor Center, or the caretakers at Hermit Lake Shelters or the Harvard Cabin.Posted 8:30 a.m. 1-25-2014. A new advisory will be issued tomorrow.

Frank Carus, Snow Ranger
USDA Forest Service
White Mountain National Forest

(603) 466-2713 TTY (603) 466-2856 

2014-1-25 Print friendly