Posted 8:15a.m., Wednesday, February 16, 2011
Tuckerman Ravine has Low and Moderate avalanche danger today. The Lower Snowfields and the Little Headwall have Low avalanche danger. Natural and human-triggered avalanches are unlikely. Watch for unstable snow in isolated terrain features. All other forecast areas in Tuckerman Ravine have Moderate avalanche danger. Natural avalanches are unlikely and human triggered avalanches are possible.
Huntington Ravine has Low avalanche danger. Natural and human-triggered avalanches are unlikely. Watch for unstable snow on isolated terrain features.
Today is a pleasant contrast from yesterday’s punishing weather. Bitter cold temperatures paired with raging winds that gusted over 100 mph (161 kph) for hours on the Summit made most people’s flight instinct take over and head for the valley. Recent snow was being whipped around through the early afternoon resulting in new wind slabs in most forecast areas in Tuckerman Ravine. As expected, the snow was unable to find a suitable landing zone in the gullies in Huntington and they are now stripped down to older snow layers. As a result there are numerous options for climbing and today’s relatively mild conditions will allow for an enjoyable experience. In Tuckerman there are a wide variety of snow conditions to be found that fall within the Moderate rating. Some areas, like Left Gully and Hillman’s Highway, can be managed safely with good route finding techniques that avoid newer wind deposited snow. Others, like the Center Bowl, Lip and Sluice, will leave you no option but to travel on the new wind slabs. These areas are well connected and if a fracture in the snow was initiated, the resulting avalanche could be fairly sizable. This is an experience I would not recommend. Expect slab hardness to vary as you move around. Softer cohesive wind slabs will be easier to trigger than the dominant hard slab that requires you to kick in hard to gain traction in places. Expect to find the softest snow down low including in the sheltered areas of the Lower Snowfields and around the Little Headwall. These two forecast areas are not well developed yet but you may find some isolated areas of instability, particularly on the north side of the Lower Snowfields toward the Little Headwall.
A warming trend will be the topic of discussion in the coming advisories. Warm air making its way into the region could topple tomorrow’s Summit record temperature of 34 F (1C). This warm air will stick around until Saturday. Our field observations will be focusing on the current stability of the wind slabs discussed above as well as analyzing how this warm weather will effect them. Depending on what we find out there, you may see an increase in the avalanche danger as a result of the warming trend. Stay tuned!
- 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.
- This advisory expires at midnight. A new advisory will be issued tomorrow.
Brian Johnston, Snow Ranger
USDA Forest Service
White Mountain National Forest
(603) 466-2713 TTY (603) 466-2856