This advisory expires at midnight.
Tuckerman Ravine has CONSIDERABLE and MODERATE avalanche danger. All forecast areas of Tuckerman Ravine have CONSIDERABLE avalanche danger except Right Gully, which has moderate avalanche danger. Natural avalanches are possible and human-triggered avalanches are likely. Careful snowpack evaluation, cautious route-finding and conservative decision-making are essential. Natural avalanches are unlikely and human-triggered avalanches are possible in Right Gully. Lobster Claw, Lower Snowfields and Little Headwall are not posted due to lack of snow.
Huntington Ravine is under a General Bulletin. You will need to do your own snow stability assessments when traveling in avalanche terrain in Huntington. A danger of falling ice exists, and will persist until it all comes down.
AVALANCHE PROBLEM: The primary avalanche hazard today is Wet Slab. With rainfall currently intensifying, the peak of avalanche danger will be this morning. Once the temperatures drop, the danger of wet slabs will decrease as the snowpack freezes. Wind slabs formed from the 5.8” of snow since Friday that turned to wet slabs are the primary threat today. These existed largely in Chute through Sluice. Worth keeping in mind is the potential for a waterfall blowout in the Lip area as both the upper and lower holes were visible this past weekend. Once the rain turns back to snow, wind slab may develop depending on how much of the forecasted 1-3” of snow we get. Conservative decision-making today will be paramount.
WEATHER: Yesterday morning, the summit received 2” of snow on strong SSW and SW winds with Hermit Lake receiving about 4”. After a lull in precipitation during the afternoon, light rain began late last night and continues this morning. It appears temperatures are peaking right about now and will decrease with an approaching cold front. Rain will likely continue until mid-morning before transitioning back to snow. Current 45mph (72kph) winds will decrease slightly and shift to the W by afternoon. By dark, the mountain may receive up to 3” of new snow.
SNOWPACK: Prior to yesterday morning, the ravine was a mixture of old surface and wind slab. Areas containing the most wind slab were the top of the hourglass in Chute, below the ice in Center Bowl, Lip, and Sluice bowl. Slopes with wind slab likely continued to load with new snow yesterday with isolated pockets growing in Left Gully and Hillman’s Highway. After steady light rain through the night, intensity has increased in the past two hours. Wet slabs are hard to predict and with limited visibility today, mitigating risk in avalanche terrain will be difficult. The lack of snow this year means the waterfalls are closer to the snow surface than in years past and at some point may run on top of the snow creating the potential for a large wet slab event. Today looks like a great day to put the spring tune on your skis in preparation for the upcoming streak of nice weather. When temperatures drop today and the rain turns to snow, the snow should bond well.
- 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.
- Posted 8:00 a.m., Tuesday, April 12, 2016. A new advisory will be issued tomorrow.
Helon Hoffer and Chris Joosen, Snow Rangers
USDA Forest Service
White Mountain National Forest
(603) 466-2713 TTY (603) 466-2716