This advisory expires at 12:00 midnight.
Tuckerman Ravine has CONSIDERABLE and MODERATE avalanche danger. Sluice, Lip, Center Bowl, and Chute have Considerable avalanche danger. Natural avalanches are possible and human-triggered avalanches are likely. All other forecast area have Moderate avalanche danger. Natural avalanches are unlikely but human-triggered avalanches are possible. Lobster Claw, Lower Snowfields, and Little Headwall are not posted due to a lack of snow in these areas.
All areas of Huntington Ravine have MODERATE avalanche danger. Natural avalanches are unlikely but human-triggered avalanches are possible.
AVALANCHE PROBLEM: Today’s avalanche problem is Wind Slab. The primary concern is the new slab that formed from snow and winds yesterday into today. This will be found in most forecast areas, particularly in the start zones of Tuckerman gullies as well as underneath ice bulges in Huntington. This new slab is on top of wind slab formed over the weekend. The potential for avalanches to step down into to this layer exists in Chute through Sluice, creating large avalanches capable of covering the floor of the Ravine.
WEATHER: Cold weather yesterday resulted in little stabilization of the weak layer that formed over the weekend. Snow yesterday started on light NW winds which quickly intensified and shifted to the west. The summit reported snow showers for much of the day and night resulting in 3.5” of 8.2% snow. The Hermit Lake snowplot recorded just over 1”. Winds shifted from NW to W and peaked during the night, gusting to 97mph. We may see a trace of snow today with west winds decreasing to 50mph. Temperatures will slowly rise into the teens and tonight may bring up to 2” of snow.
SNOWPACK: The life of the meager snowpack around Mount Washington was extended this past week thanks to cold temperatures, good loading winds, and new snowfall. Prior to yesterday’s new snow, the surface consisted of old surface with areas of wind slab resting on aspect-dependent weak layers. South facing aspects were subjected to significant temperature changes and are sitting on a layer of developing facets. East and north aspects have seen less sun, have a thicker layer of new snow, and have a layer of graupel as the weak layer. Areas rated Moderate today, with the exception on Central, tended to have more exposed old surface rather than this wind slab.
Throughout the day, wind speeds increased to 70mph+ and remained there for the night. Winds of these speeds will transport a significant amount of snow into Tuckerman, particularly in lee areas under the Headwall. Huntington will have some areas scoured by these winds, but also areas that develop on strong slab, such as under the ice in Central. Safe travel through avalanche terrain today will require cautious route-finding that may be made difficult at times due to blowing snow and poor light.
- 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 9:00a.m., Tuesday, March 22, 2016. A new advisory will be issued tomorrow.
Helon Hoffer, Snow Ranger
USDA Forest Service
White Mountain National Forest
(603) 466-2713 TTY (603) 466-2856