This advisory expires tonight at 12:00 midnight.
Tuckerman Ravine has MODERATE and LOW avalanche danger today. The Sluice, Lip, Center Bowl, and Chute have Moderate avalanche danger. Natural avalanches are unlikely and human triggered avalanches are possible. All other forecast areas of Tuckerman have Low avalanche danger. Natural and human triggered avalanches are unlikely. Unstable snow may exist in isolated terrain features.
Huntington Ravine has LOW avalanche danger today. Natural and human triggered avalanches are unlikely. Unstable snow may exist in isolated terrain features in these locations.
AVALANCHE PROBLEM: Wind Slabs are the primary issue today, although isolated across the terrain. High winds peaking at 115 mph on Tuesday night did a good job scouring many areas to the old hard rain crust from 3 days ago. Across the Ravines, Wind Slabs will be isolated to the most protected areas from W winds. Pockets beneath steeps bulges and terrain features are locations to look for these wind slab instabilities.
WEATHER: Cold air is still in place with the summit currently at -10F with gusting winds to about 90mph from the NW. Some light new snow accumulations will fall, but should not add up to much. However the light aerosol of snow will hamper visibility. Wind velocities are forecasted to slacken through the day with temperatures slowly rebounding as we head toward the weekend, perhaps hitting the freezing mark by Saturday. As we discussed yesterday, be ready for full winter conditions this morning with the right experience and equipment. If venturing above treeline assure you have very good Arctic mountaineering clothing with a focus on your most vulnerable parts, the hands, feet and head. As we move into the afternoon winds will drop substantially with temperatures heading into the singles above zero. This warming trend will move the mercury into positive territory for the first time in several days.
SNOWPACK: The warm and rainy weather on Monday, with the Arctic freeze up that followed, have made weaknesses below the hard crust layer inconsequential. This frozen, icy, hard, bridging layer has a high degree of tensile strength that will take a large impact to overcome. Stepping down through this layer would take something as influential as a new snow avalanche compared to your weight. Therefore a human trigger will only be an issue in new slab that has developed from the few inches of snow over the last several days. These wind slabs will be isolated due to the very high winds the mountain has seen over the past 36 hours. The main location in either Ravine to find new slabs will be across Tuckerman’s Center Bowl and Lip. Be suspicious. But generally across the eastern side of Washington, screaming winds from Tuesday night and this morning have scoured most areas down to the icy crust from Monday night. Some snow showers are expected today which may once again cause some new loading as wind speeds drop. New accumulations will be light so I would suspect it is unlikely the problem will be anything more than isolated.
The very hard slick surfaces that exist, coupled with a strong wind this morning close to 90mph, will make falling in steep terrain is a real concern. Mountaineering experience in these conditions and the ability to execute an immediate self-arrest with your ice ax is essential. Once moving not even the most skilled mountaineers with a lifetime of experience could stop on this surface.
- 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 7:50a.m. Thursday January 9, 2014. A new advisory will be issued tomorrow.
Christopher Joosen, Snow Ranger
USDA Forest Service
White Mountain National Forest
(603) 466-2713 TTY (603) 466-2856