Tuckerman and Huntington Ravines have Low avalanche danger. Natural and human triggered avalanches are unlikely except in isolated terrain features. Isolated pockets of slab do exist with in isolated terrain features so see the fine points addressed below.
Upslope snow events keep giving us scant amounts of new precipitation changing little on the mountain, but they are keeping us on our toes. Since late on Friday we’ve picked up about 2” of new snow on the Washington massif as of midnight, with an additional “trace to 2 inches” forecasted for the next 18 hours. Over the weekend relatively very light winds have moved little snow into the ravines. Therefore 1-2” still sits above treeline waiting to board their flights from the alpine zone concourse later today as wind velocities rise. Winds will increase from 40-65mph to 85mph with higher gusts in the afternoon. This will start a loading event for the Ravines, predominately in Tuckerman Center Bowl and Lip. So when we discuss a “loading event” the danger should be above Low right? Well….usually.
Last week’s thaw has created scattered nooks and crannies above treeline that will be small catchment areas providing less snow for transport to lower slopes. The warm spell with rain also dramatically reduced the thin size of bed surfaces for future avalanches. These 2 points were the drivers in our forecasters meeting this morning and the decision factors to keep areas at Low. To recap, we will have some loading today and get close to ‘Moderate’ in several areas such as Tuckerman’s Lip, Center Bowl and Chute. In Huntington Ravine, the target areas to watch will be Central, Pinnacle and Odell. Treat new pockets with suspicion as they will be loading on either old icy surfaces or on a thin layer of unconsolidated snow. However the peppered distribution of any new slabs will be able to be avoided by remaining on old surfaces. This isolated nature of slabs fits well within the “Low” rating, but expect an increasing danger trend in strong lee areas over the next 24 hours.
As Frank mention yesterday the old hard surfaces are very slippery. These old surfaces are camouflaged by newer snow in places and threaten those on angled terrain with long sliding falls. An ice ax, crampons and the skills and experience to use them well are imperative. The Tuckerman Ravine trail from Pinkham to Hermit Lake has significant stretches of water ice erupting onto the surface and covered thinly by new snow. A minimum of ski poles and microspikes are needed to avoid frequent falls due to hidden blue ice. Time since the thaw has diminished the potential for ice dams on alpine climbs but the threat still exists. Running water under pressure behind surface ice may be looking for a release such as an ice tool placement. Protecting climbs with well thought out ice screws and rock gear is an intelligent choice. Soloists should keep the ice dam hazard in mind when selecting a route.
If you like an extreme challenge or are considering shaking out those old fillings the Sherburne trail will comply as very hard chattery ice exists. I would prefer ski runs that have the benefit of “eastern tillers” with deep grinding teeth to chew up water ice. It’s rare that I would suggest lift serve sliding over the woods, but until we get at least a few inches it is rough going in the backcountry.
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 8:25 2-04-2013This advisory expires at midnight. 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