Avalanche Advisory for Monday, January 22, 2018

Huntington and Tuckerman Ravines have LOW avalanche danger. Watch for unstable snow on isolated terrain features.  The Little Headwall is mostly open water or frozen waterfall ice.

Due to the open waterfall hole and a 20’ high avalanche crown line, the Tuckerman Ravine Trail is closed in the Ravine between Lunch Rocks and the Alpine Garden Trail. Please use the Winter Lion Head Route if going to the summit from Pinkham. Other routes to the summit from the east side are significant mountaineering challenges.

 AVALANCHE PROBLEM: Winter weather is inbound though the small amount of snowfall forecast today has minimal potential to elevate our avalanche danger. More isolated pockets of wind slab may develop from new snow on moderate winds today and tonight remain our primary avalanche problem. Small in size, if triggered these slabs aren’t likely to bury you but could cause a long sliding fall on our largely rock hard snow surface. Until more significant accumulation of snow and mixed precipitation late tonight and into tomorrow, sliding falls above numerous hazards remain a primary concern for travelers in steep terrain.

 WEATHER: A relatively warm low pressure system is moving in from the west, though we’re unlikely to see more than an inch of new snow before dark today. Summit temperature should peak in the lower 20’s F and wind will be out of the SW in the 15-30 mph range. Precipitation is forecast to continue tonight and tomorrow, transitioning to a mix of sleet, freezing rain, and rain as summit temperature pushes towards the freezing point by Tuesday morning. The few inches of snow that will likely fall tonight should see some amount of transport by southwesterly wind before warmer temperatures and wetter precipitation limits the wind’s ability to move snow on the ground.

SNOWPACK: The precipitation forecast to begin as snow today and transition to a wintry mix or possibly rain by tomorrow will fall on a largely rock hard surface. We don’t expect sufficient snow during daylight hours today to warrant new stability concerns. Depending on timing of more significant snowfall tonight as well as the forecast changeover to wetter precipitation, we could see greater wind slab development around the time this advisory expires at midnight tonight. The robust surface crust limits our concern for deeper instabilities, with one exception. Snow above the crown line at the top of the massive wet snow avalanche out of the Lip late last week is unsupported and could become unstable with wet and warm conditions tomorrow. We don’t expect this to occur today, with below freezing forecast temperatures that should keep our existing snow very firm. Long sliding falls should remain a key concern for travelers in the alpine.

Please Remember:
• Safe travel in avalanche terrain requires training and experience. This bulletin 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 Harvard Cabin.
• Posted 7:30 a.m., Monday, January 22, 2018. A new advisory will be issued tomorrow.

Ryan Matz, Snow Ranger
USDA Forest Service
White Mountain National Forest
(603) 466-2713 TTY (603) 466-2856

2018-1-22