Avalanche Advisory for Tuesday, March 6, 2018

Huntington and Tuckerman Ravines have LOW avalanche danger. All forecast areas have Low avalanche danger. Watch for unstable snow on isolated terrain features.

 AVALANCHE PROBLEM: Pockets of wind slab remain our avalanche problem as snow struggles to stick to the icy old surface in most areas. Right Gully and Lobster Claw in Tuckerman Ravine have the most continuous new snow which thinly disguises the icy surface and recently formed wind slabs alike. The same Northeasterly wind which did not scour these lee gullies in the past 36 hours resulted in similar conditions in North, Damnation, and Yale in Huntington Ravine. All other forecast areas have significantly more old grey, icy surface exposed. The pockets of wind slab you’ll find throughout the terrain will vary in character but likely remain reactive to a human trigger. Any potential avalanches would be relatively small in size but could knock you off your feet and cause a high speed sliding fall on the icy old snow. This old snow that is hard and smooth is nearly impossible to arrest a fall on, so consider the consequences in terrain you choose and take care to not fall.

 WEATHER: No precipitation and moderate wind speeds yesterday resulted in minimal change to conditions. Today is forecast to bring at least partial clearing of cloud cover as temperatures on the summit approach 20F. Wind will shift from NE to E and remain below 30 mph. These pleasant conditions should persist through tonight before cloud cover, wind, and ultimately snowfall roll back in tomorrow as another Nor’easter approaches. It’s a bit early in the game to commit to forecast snow totals, but we’re optimistic this system will bring more snow than the coastal storm of last weekend.

SNOWPACK: Though we’ve had a few inches of snow in the past week, wind has easily transported it and scoured a majority of our terrain to icy old snow. The multiple melt/freeze cycles which helped form this hard snow surface also stabilized our snowpack, making the pockets of wind slab formed since late last week the only avalanche concern. Avoiding this avalanche problem is straightforward in areas where the grey old snow contrasts the white wind slab, but more challenging in areas like the northern gullies of both ravines where less wind scouring has resulted in less old grey surface. We don’t expect large wind slabs in any terrain. Long sliding falls on the hard, icy old snow remains a key hazard which demands respect. Clearing may allow select sun-exposed slopes to soften slightly but only briefly this afternoon. The current firm conditions which provide good crampon and ice axe travel mean limited options for decent turns, but the John Sherburne Ski Trail has improved and offers decent skiing and riding conditions with a few thin spots.

The Harvard Cabin will be open all nights this week thanks to a fill-in caretaker.

Remember:
• 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 Harvard Cabin.
• Posted 6:45 a.m., Tuesday, March 6, 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

2018-3-6