Avalanche Advisory for Sunday, 2-19-2012

Expires 12:00 midnight, February 19, 2012

Tuckerman Ravine has CONSIDERABLE and MODERATE avalanche danger.  The Sluice, Lip, Center Bowl, and Chute have Considerable avalanche danger. Natural avalanches are possible and human triggered avalanches are likely. Right Gully, Left Gully, and Hillman’s Highway have Moderate avalanche danger. Natural avalanches are unlikely and human triggered avalanches are possible. The Lobster Claw has Low avalanche danger. Natural and human triggered avalanches are unlikely except in isolated terrain features. The Lower Snowfields and the Little Headwall are not posted due to an overall lack of snow. Forecasts for these locations will begin when conditions warrant.

Huntington Ravine has MODERATE and LOW avalanche danger.  North, Damnation, Pinnacle, Odell, and the Escape Hatch have Low avalanche danger. Natural and human triggered avalanches are unlikely except in isolated terrain features. Yale, Central, and South gullies have Moderate avalanche danger. Natural avalanches are unlikely and human triggered avalanches are possible.

Five inches (13cm) of new snow in the past three days has done a lot to change the appearance of the ravines since the last time they were basking in sunlight on Thursday. What had been a mix of wind effected slabs, ski and boot tracks, and crusts is now covered in a smooth blanket of creamy white windslab. This is what winter up here is supposed to be like. The weather today is going to play a role in the avalanche danger rating. Currently winds are blowing from the NW at 55-65mph (89-105kph), and blowing snow is coming in from above the ravines. This active loading is preventing me from dropping the danger rating in the Sluice through the Chute in Tuckerman. More than a couple times, I’ve seen bluebird days just like this where low drifting snow into the Lip and Bowl is sufficient to trigger an avalanche. As high pressure builds in, winds will decrease in velocity. This may shut down wind loading altogether and eliminate the potential for naturally-triggered avalanches, which in turn would bring the avalanche danger down to Moderate. The snow that will be leftover will still be worthy of careful stability evaluation if you are looking to get out onto the slopes. This morning there are crown lines visible from recent avalanches in the Duchess and the Center Bowl. These should be considered “bulls-eye” data that indicate the presence of unstable snow. The crown in the Bowl has mostly reloaded and may not be visible for much longer if the wind loading persists. As with the past few days, the primary threat is the newly developed slabs from the recent snow.

Some areas of Tuckerman offer better options than others for traveling through avalanche terrain. Due to the low snow totals this season, the terrain on the northern side, i.e. Right Gully and Lobster Claw, has more discontinuous snowfields and more islands of safety that you can link together. Areas such as Hillman’s and Left Gully will make it more difficult to avoid exposure to the avalanche paths. Keep in mind there are lots of human factors at play today. It’s the first sunny day after a snowfall, it’s a holiday weekend, and the snow looks like it would be a joy to ski or ride…all these mean you’ll need to be heads up not only for yourself, but for what others are doing nearby.

Huntington has a mix of Low and Moderate danger. In those locations rated Low, expect to find small pockets of unstable new snow. Areas such as above the ice in Odell, near the top of Pinnacle, and in climbers’ right side of the Escape Hatch are examples of where you might find these. The locations rated Moderate have larger snowfields that are too big to call “pockets”. Whether the slab you encounter is small or large, you’ll want to evaluate the stability and do your best to avoid traveling through unstable snow. The consequences of even a very small slide in Huntington can be severe.     

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 8:35am. A new advisory will be issued tomorrow.

Jeff Lane, Snow Ranger
USDA Forest Service
White Mountain National Forest
(603) 466-2713 TTY (603) 466-2856

2012-02-19 Print Friendly