Avalanche Advisory for Monday, February 5, 2018

This advisory expires at midnight.

Huntington Ravine will have HIGH and CONSIDERABLE avalanche danger. Central Gully has High avalanche danger. Very dangerous avalanche conditions exist. Travel in avalanche terrain is not recommended. All other forecast areas have Considerable avalanche danger. Careful snowpack evaluation, cautious route-finding, and conservative decision-making are essential.

Tuckerman Ravine will have HIGH and CONSIDERABLE avalanche danger. Sluice, Lip, Center Bowl, and Chute have High avalanche danger. Very dangerous avalanche conditions exist. Travel in avalanche terrain is not recommended. Lobster Claw, Right Gully, Left Gully, Hillman’s Highway, and the Lower Snowfields have Considerable avalanche danger. Careful snowpack evaluation, cautious route-finding, and conservative decision-making are essential. The Little Headwall is not rated due to a lack of snow.

AVALANCHE PROBLEM: The primary avalanche problem today is windslab. This windslab will be created from snow that fell overnight being subjected to increasing and shifting wind. As wind speed increases today, so will the avalanche hazard. The shift in wind direction will mean that all slopes will experience loading from several directions, leading to windslabs of varying characteristics. Due to the amount of snow and wind speeds ideal for loading, the potential for large natural avalanches exists today. Entering the floor of either ravine today will put travelers in avalanche terrain due to the potential size of avalanches today. Dangerous avalanche conditions exist today with natural avalanches likely on our biggest terrain.

WEATHER: Snow fell through the day yesterday, delivering just over 9” to the Summit and 5.6” to Hermit Lake. Snow at the Summit had a density of 10% while snow at Hermit Lake was at 12.3%. Snow fell heaviest from 5pm to midnight yesterday while wind blew from the SSW at 40-60mph. Snowfall is tapering this morning and wind bottomed out at W 35mph before increasing back to 60mph. Wind speeds should increase slightly more and shift to the NW, before sitting at NW 60-80mph for the daylight hours and decreasing again tonight.

SNOWPACK: The snow that fell on top of the January thaw/freeze turned what was broken and textured into a smooth surface. This will likely be the bed surface for avalanches today. As wind increases today and shifts to the NW, our snowpack will develop an upside-down characteristic, with touchy windslab rapidly developing. Avalanche terrain will continue to be loaded with snow as the day progresses, increasing the avalanche danger. Multiple avalanche cycles are possible today with the potential for paths to run large and far.

The John Sherburne will be skiing well, despite the occasional hidden rock and chunk of frozen turf, and will provide a safe alternative to avalanche terrain today.

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 8:30 a.m., Monday, February 5, 2018. A new advisory will be issued tomorrow.

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

2018-02-05