Avalanche Advisory for Monday, January 29, 2018

Huntington Ravine has LOW avalanche danger. All forecast areas have Low avalanche danger. Watch for unstable snow on isolated terrain features.

Tuckerman Ravine has LOW avalanche danger. All forecast areas have Low avalanche danger. Watch for unstable snow on isolated terrain features. Little Headwall has not refrozen completely and is far from filled in with snow so is not rated. The Lip still contains a large void in the snowpack from the wet avalanche on January 12 or 13.

AVALANCHE PROBLEM: A firm and icy snowpack with some areas of mostly stubborn wind slab mark our terrain. These wind slabs are unlikely to produce an avalanche but are worth evaluating for signs of a weak bond to snow beneath or a tendency to sustain a crack along the surface. The wind slabs in question are easily visible and identified by contrast to the gray and dirtier looking, refrozen snow.

WEATHER: It’s 15F at Hermit Lake this morning with calm winds, a few clouds and no precipitation recorded since January 24. Today, the summit will see partly cloudy conditions with a high of 13F and light winds in the 20-35 mph range. Summit fog is clearing this morning but high clouds will move in later today. Temperature and winds will remain mild and relatively calm today through Wednesday before shifting southwest as a bit of moisture arrives on Thursday. A better chance of more significant snowfall comes on Sunday.

SNOWPACK: The dominant feature of the snowpack in Tuckerman Ravine yesterday, in addition to the yard sale of refrigerator-sized blocks of ice from the wet avalanche, was the knife hard, ice glazed surface. Crampons were necessary to climb beyond the floor of Tuckerman Ravine due to this slick and hard surface with similar conditions in Huntington. Stability tests and travel in Left Gully to the choke, about ¾ of the way up, on Saturday showed that the older wind slab was well bonded to this icy surface. Nearer the surface, firmer (1F) wind slab over the thicker 4F slab created a clean shear at the interface between these two layers but neither layer showed any desire to propagate a crack much beyond your feet. Snow and ice climbs are in great shape now and looks as if we have a few days of calm weather and good visibility to enjoy them. The firm snow provides for quick and efficient cramponing but is an unforgivingly fast surface if you stumble so stay vigilant!

Microspikes and crampons are key tools for travel today. Crampons are needed on the steeper slopes and above treeline. Conditions on the Sherburne Ski Trail remain grim though passable for those desperate for a lap. Seems like the folks running to and from Hermit Lake and the summit yesterday had the right idea.

Please 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 8:00 a.m., Monday, January 29, 2018. A new advisory will be issued tomorrow.

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

2018-01-29