Avalanche Advisory for Monday, February 16, 2015

This advisory expires tonight at 12:00 midnight.

Tuckerman Ravine has Moderate and Low avalanche danger today. Lobster Claw, Right Gully, Sluice, Lip, Center Bowl, and Chute have Moderate avalanche danger. Natural avalanches are unlikely but human-triggered avalanches are possible. Heightened avalanche conditions on specific terrain features exist. Left Gully, Hillmans Highway, Lower Snowfields and the Little Headwall have Low avalanche danger. Natural and human-triggered avalanches are unlikely.

All forecast areas of Huntington Ravines have Low avalanche danger. Natural avalanches and human-triggered avalanches are unlikely. Watch for unstable snow on isolated terrain features.

AVALANCHE PROBLEM: Extreme northerly winds continue to work on the snowpack. Higher and more exposed areas are being scouring while certain leeward and lower elevation spots are catching snow and building hard, stubborn and potentially large wind slabs. If you managed to crawl against the wind into these Moderate rated areas you could trigger a dangerous hard slab avalanche given the right terrain feature, slab thickness or more accurately thin-ness.

WEATHER: Probably the more prevalent danger than today’s avalanche problem is the high wind and cold temperatures. The last four hourly observations on the summit show NNW winds blowing steadily from 105-119 mph with gusts as high as 131 mph. Temperatures will warm slightly to -15F and wind will diminish some to the 70-90 mph range later this afternoon but expect extremely challenging conditions above tree line until then. Even below tree line, the danger of frostbite is real this morning. Falling trees and branches present a real risk and drifting on trails will slow progress. Gusts at Hermit Lake are testing the cabin’s construction and remind me of tornadoes and hurricanes that I have experienced. Jeff and I had to cut our way through two live downed trees on the Tuckerman Ravine trail to get to Hermit Lake. It is not nice day out.

SNOWPACK: Severe weather or low visibility have kept us from getting into the field over the last 4 days to dig for weak layers and assign numbers to our instabilities using the standard battery of snow stability tests. Weather history, some visual assessments and institutional knowledge all point to the obvious issues in the upper snowpack as being the most concerning feature. In addition to wind slabs loading in today, thicker wind slabs which developed Thursday and Friday and a thinner slab problem from the weekend are out there scattered around the terrain.  Older hard surfaces are also exposed in places making for challenging and potentially hazardous climbing on steeper terrain such as the Fan in Huntington or the lower slopes of Tuckerman Ravine without the use of crampons. Hopefully the snowpack discussion today is just an academic exercise in snow science without any application to your recreational goals in higher terrain today.

Current rescue operations are going on in the northern Presidential range so please yield to these rescue efforts. Expect drifting snow, limbs, branches and possibly downed trees as well as very firm snow on all trails including the John Sherburne ski trail 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 the Harvard Cabin.
  • Posted 8:45 a.m. February 16, 2015. 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

2015-02-16 print friendly