All forecast areas of Tuckerman Ravine have CONSIDERABLE avalanche danger today. Natural avalanches are possible and human triggered avalanches are likely. The only exceptions to this are the Lower Snowfields and the Little Headwall which have Moderate and Low avalanche danger. In the Lower Snowfields, natural avalanches are unlikely and human triggered avalanches are possible.
Huntington Ravine has CONSIDERABLE and MODERATE avalanche danger. Yale, Central, Pinnacle, Odell and South Gullies have Considerable avalanche danger. Natural avalanches are possible and human triggered avalanches are likely. North and Damnation Gullies and the Escape Hatch have Moderate avalanche danger. Natural avalanches are unlikely and human triggered avalanches are possible.
I had an April Fool’s advisory kicking around in my head that involved 18″ of champagne powder falling on no wind but pulling into Pinkham Notch this morning and seeing 3″ (7.5cm) of snow coating the branches doomed that joke. Truth is, 3″ of 6% snow was recorded at Harvard Cabin and Hermit Lake with 1-3″ (3-7.5cm) more forecast to fall through the day on increasing winds. These conditions will make travel in avalanche terrain nothing to joke about. The snow we recorded here was light in spite of warm temperatures and will be easily transported by the wind today which will wrap around from the SSE through the south then west and really get going this afternoon and evening when it will eventually start blowing 55-75 mph (90-120kph) out of the west. The timing of all this is the question since our ratings are more or less tied directly to the increasing winds. Right now the new snow on very light winds is keeping our ratings down one notch so it’s possible that dawn patrol skiers or climbers could run the gauntlet and pass through avalanche terrain without too much concern for natural avalanche activity but doing so would require just the right timing, assessment and risk tolerance. It is snowing very lightly now and the additional upslope enhanced snowfall through the day will increase the probability of human triggered avalanches as well as the potential for natural avalanches by creating windslabs in lee terrain as winds ramp up and shift. The exact location of the lee areas is a moving target today so at a minimum you will need to assess the danger of the new snow falling on steep terrain. Available snow on the ground and new snow will quickly form sensitive slabs as the wind increases in velocity. There is still quite a bit of snow from last week in the Alpine Garden that will add to the amount of snow available for the wind to move into our avalanche start zones as evidenced by the powder clouds that skiers were kicking up even during the warmest parts of the day yesterday. Poor visibilty due to low clouds and blowing snow will add to the challenge due to the inability to view snow plumes and other evidence of snow being moved into avalanche start zones.
Snow temperatures beneath the 7.5 cm (3″) of new snow are just below freezing so the packed snow under the new snow on the Sherburne will probably allow good edging rather than an ice “dust on crust” situation. Those skiers not willing to risk an encounter with the avalanche dragon might prefer a run there today.
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 at 8:25a.m., April 1, 2013. A new advisory will be issued tomorrow.
Frank Carus, Snow Ranger
USDA Forest Service
White Mountain National Forest
(603) 466-2713 TTY (603) 466-285