This advisory expires at 12:00 midnight.
Tuckerman and Huntington Ravines have Moderate avalanche danger. Natural avalanches are unlikely and human triggered avalanches are possible. Evaluate snow and terrain carefully. The only exceptions to this are the Little Headwall in Tuckerman and Pinnacle Gully in Huntington, which both have Low avalanche danger. Natural and human triggered avalanches are unlikely. Unstable snow may exist in isolated terrain features.
AVALANCHE PROBLEM: Avalanche problem #1 today is wind slab. The most concerning of these can be found in the middle of Tuckerman, between the Sluice and the Center Bowl. Other areas in Tuckerman, as well as much of Huntington, also fall in the Moderate range. With careful snowpack assessments and conservative choices you may find slopes stable enough to travel through while avoiding potential instabilities. In Pinnacle Gully, the concern lies in the snowfield exiting the route. The climb itself is pretty well wind scoured. Northern gullies in Huntington have potentially unstable snow leading up to the routes as well as in the lower to middle sections. In the gullies to the climber’s left of Pinnacle you’ll find the issues in the middle to upper sections.
WEATHER: Today should be a little warmer than yesterday and with a lot less wind. You should still be expecting a cold day with increasing clouds. Summit temperatures will be in the single digits F (-15C), winds are already lighter than the forecasted 15-30mph range (24-48kph).
SNOWPACK: As I mentioned yesterday, the snowpack in the Center Bowl and Lip area has grown tremendously in the past couple weeks. Within this area, you should expect numerous layers of wind slab. Initial failure of the slope could take place at any one of these, however, I’d put my money on a graupel layer that fell from the sky on Friday as being the weakest of the weak layers. A couple easy compression test results yesterday had the block sliding on this layer, then falling down and breaking up into multiple layers the way a stack of books might look if it fell off the coffee table.
Many areas in both ravines have received a fair amount of wind effect. Left Gully and South Gully are two examples. This hammering of the wind has the potential to add strength and stability to the snowpack, but unless you’ve been able to assess the snow with your own hands, don’t assume a slope is stable simply due to its visual appearance. The surface layer may provide a false sense of security and mask underlying weaknesses.
- 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 Visitor Center, or the caretakers at Hermit Lake Shelters and Harvard Cabin.
- Posted 8:00a.m. 03-25-2014. 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