Avalanche Advisory for Thursday, February 8, 2018

Huntington Ravine has HIGH and CONSIDERABLE avalanche danger. Central, Pinnacle and Odell have High avalanche danger. Very dangerous avalanche conditions exist. North, Damnation, Yale, South and Escape Hatch have Considerable avalanche danger. Cautious route-finding and conservative decision making is essential.

Tuckerman Ravine has HIGH and CONSIDERABLE avalanche danger. Very dangerous avalanche conditions exist today in Sluice, Lip, Center Bowl, Chute as well as the floor of the Ravine. Natural avalanches are likely in those areas. Lobster Claw, Right and Left Gully, Hillmans Highway and Lower Snowfields have Considerable avalanche danger. Human-triggered avalanches are likely there so cautious route finding and conservative decision making are essential. Little Headwall has Moderate avalanche danger and may still contain some open water and holes in the snowpack.

AVALANCHE PROBLEM: Wind slab avalanches are likely to occur this morning in areas with a high rating. These areas contain the greatest potential to avalanche naturally due to their position downwind of a sizable fetch as well as their larger size. Considerable rated areas will be dangerous as well. Route-finding in these areas will be difficult due to low visibility and continued wind transport of snow, especially this morning. Peak natural avalanche activity is likely occurring this morning and though we may be moving towards better stability this afternoon, the potential for triggering large, lingering wind slabs will remain through the day. Today is a good day to seek lower angle terrain in sheltered areas and to avoid being in the runout of avalanche paths.

WEATHER: The Hermit Lake snowplot received 20 cm (7.8”) of new snow yesterday with the summit reporting 8.2”. Yesterday afternoon the temperature at Hermit Lake reached 23F while the summit climbed to 21F. Wind packing and warm temperatures are likely responsible for the relatively high density figure of 13% recorded this morning at Hermit Lake. Wind speeds are currently pegged near 70mph on the summit with active wind transport of snow limiting visibility in both Ravines. These NW winds will shift west and diminish a bit. A trace to 2” of new snow today is possible.

SNOWPACK: Field observations yesterday indicated much lower snow density figures at the start of the storm with sensitive slabs and frequent natural sluffing occurring in the early afternoon. These observations lead us to believe that the snow that hasn’t yet been blown into the terrain and avalanched naturally will do so this morning. If a slope has not avalanched, it is likely near the tipping point due to the lower density and weaker snow beneath the new cohesive wind slab. Areas of older and hollow sounding, pencil hard wind slabs existed in wind sheltered areas of Hillman’s Highway yesterday. These slabs likely exist in other sheltered areas and could contribute volumes of snow to a larger avalanche stepping down into them.

The Sherburne Ski Trail is a great alternative to skiing in avalanche terrain today.

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 Harvard Cabin.
• Posted 8:00 a.m., Thursday, February 8, 2018. 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