This advisory expires at 12:00 midnight, March 22, 2013.
All forecast areas of Tuckerman and Huntington Ravines have MODERATE avalanche danger. Natural avalanches are unlikely and human triggered avalanches are possible. Heightened avalanche conditions exist. Evaluate snow and terrain carefully and identify features of concern. The only exception is the Little Headwall, which has Low avalanche danger. Watch for unstable snow in isolated terrain features here.
Today we are treated to an unexpected bluebird morning in the ravines, which is allowing us to get great visual observations of what’s taken place here since the latest storm began. On the whole, it’s definitely a “heads up” kind of Moderate today. The storm dropped a large quantity of snow across the mountain, which was subsequently blown into the ravines on strong NW winds and produced numerous avalanches in many locations. Recent avalanche activity is a red flag that should heighten your awareness of the avalanche risk. This morning that red flag is standing straight out and strong in the relatively windless ravine. If winds increase as forecasted and additional snow loading begins to occur, that is another red flag and should cause you to reconsider whatever plan you have made.
The stability problems we’re dealing with today are the result of the aforementioned storm and wind event. Snow began on Tuesday, but it wasn’t until Wednesday morning that the winds shifted to the NW and increased in speed. This created a situation of significant windslab development across all aspects. Avalanches occurred at various times during the storm, which allowed some slopes to see a lot of reloading while others still show sharp crown lines indicating they took place later in the avalanche cycle. Thursday ended with clear skies and some solar gain on S-facing slopes. This created a sun crust on some of these aspects, but I doubt that the sun’s effect was strong enough to completely stabilize these slopes. In fact, it just might be enough to provide a false sense of stability if one were to only make assessments in the upper layers, such as with a ski pole probe or the feel of snow beneath one’s skis.
We often are able to pick out a couple specific areas where we have our greatest concerns. Today, new windslab is sufficiently widespread to make just about all areas an “area of concern.” For example, in all locations of Tuckerman I would be cautious about venturing up without a clear idea of why I was going there. Sluice did have a recent avalanche, but there is still a large amount of hangfire sitting in very steep terrain above the crown line. The Lower Snowfields, Right Gully, and Lobster Claw are the areas with the lowest likelihood of avalanches today, but they still easily fall within the Moderate range.
Huntington has stability concerns in many areas as well. In Yale, Damnation, and North, the problems are greatest in the mid-sections of the gullies. Central has a lot of new slab throughout. Pinnacle and Odell have slab on the approach to the ice as well as up above the ice. We’ve had lots of accidents and close calls on these approaches after similar events, so be sure to begin assessing snow carefully long before you swing a tool. South and Escape Hatch have a lot of windslab near the exits. So as you can see, the problems truly are widespread today.
Enjoy the sunshine while we have it. The forecasted weather was for summits being firmly entrenched in fog, so visibility may deteriorate rapidly at any time today. We’ll have an Weekend Update for you this afternoon or evening after our field work 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 8:40 a.m. Friday, March 22, 2013. 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