This advisory expires at midnight, Thursday 4-26-2012.
Tuckerman Ravine has Low avalanche danger. Natural and human triggered avalanches are unlikely.Huntington Ravine is under a General Advisory. You will need to do your own snow stability assessments when using avalanche terrain in Huntington. A danger of falling ice exists, and will persist until it all comes down.
A general clearing trend this morning will carry the current summit mercury at 17F up to about 30F, perhaps allowing for some softening in the Ravine. Until then snow conditions will remain hard making travel a little tenuous under ski or boot without crampons. This afternoon, the increasingly clouds of late morning will make precipitation more likely. This will likely be a mixed event giving up a variety of crystal types, freezing rain, and good ole regular liquid. Colder air ushered in by a shifting and increasing wind will change any mixing precipitation back to all snow tonight and tomorrow. Between the beginning of moisture this afternoon and ending tomorrow evening we are forecasted to receive 2-6” of new snow for the period. This may develop new avalanche concerns due to slab develop from a NW wind beginning tonight at 35mph and building to over 85mph tomorrow. Be sure to check the Friday avalanche advisory on this developing issue. A quick mention of the weekend is deserved as it currently looks sunny, albeit a bit chilly. Until then, the mountain should only see about an inch of mixed snow late today, with the majority of the 2-6” coming tonight and tomorrow. Expect the increasing clouds and fog later today to limit a good visual hazard assessment of the terrain. In particular seeing your run out will be important to assess what you might slide into in case of a fall. Ask the question, “If I fall what is below me that I will be sliding into at a high rate of speed?” Rocks, cliffs, crevasses, and bushes dominate the run out in most areas. Assessing all the objective hazards together Left Gully harbors the least risk when comparing it to other locations around the Ravine. Of course less doesn’t mean none, so stay attentive and start conservatively. Due to the on and off nature of hard icy snow surfaces good mountaineering skills, crampons with front points and an ice ax to arrest a fall are essential and highly recommended for safe travel on steep snow.
CREVASSESAND UNDERMINED SNOW exists in many areas. These were made worse by the heavy rain earlier this week. Always climb up what you plan on descending so you can assess the hazards at a more leisurely pace. The largest crevasses exist from the Lip towards the south across the Center Headwall over to the Left Headwall, but smaller slots are growing in the Sluice and the Chute. Undermining or running water has increased the collapse hazards near holes, rock and crevasses as well. The lower sections of Hillman’s Highway have become discontinuous due the snowpack collapsing near the exposed rocks.
ICEFALL will continue to be a significant issue until it has all come down. Many people have been injured or killed through the years by falling ice and remember that even a small piece of ice impacting you at high speed can cause a lot of damage. Ice and rock has been falling from a variety of locations, including the less common areas such as Left Gully, the Chute, and Right Gully. But the dominate ice hazards are still from the Sluice moving south over to the Center Headwall. Due to harder snow conditions after the rain and cold air, ice can go much faster and farther than a week ago so realize you don’t need to go far to be at risk. Presently, if you’ve reached the snow line in the floor, you’re within striking distance of icefall!
THE TUCKERMAN RAVINE TRAIL IS CLOSED TO ALL USE FROM LUNCH ROCKS TO THE JUNCTION WITH THE ALPINE GARDEN TRAIL. This includes the Lip area as well as this section of the hiking trail. This annual closure is due to the magnitude of crevasses and undermining that develop in this area during the spring melt-out. A fall in this area would have severe consequences. The trail to the floor of the ravine is open from down below, as is the section above from the summit down to the Alpine Garden junction. Use an alternate route to circumvent this closed section, such as the commonly used Lion Head trail. The John Sherburne Ski trail is also closed to all use.
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 caretaker at Hermit Lake Shelters. A new advisory will be issued tomorrow.
Christopher Joosen, Snow Ranger USDA Forest Service, White Mountain National Forest