Avalanche Advisory for Tuesday, April 28, 2015

This advisory expires tonight at 12:00 midnight.

Tuckerman Ravine has Moderate avalanche danger. Natural avalanches are unlikely and human-triggered avalanches are possible. The only exceptions are Hillman’s Highway, the Lower Snowfields, and Little Headwall which have Low avalanche danger. Natural and human-triggered avalanches are unlikely in these locations. Huntington Ravine is under a General Advisory. You will need to do your own snow stability assessments when traveling in avalanche terrain in Huntington.

AVALANCHE PROBLEM: As winter refuses to release Mt. Washington from its grip, wind slab avalanches are the primary threat again today. Yesterday’s snowfall brought yet another round of snow into Tuckerman, which was likely transported on northerly winds into aspects that have a southerly-facing component. Expect the greatest avalanche danger to be found on the looker’s right side of Tucks as well as in the Lip and Center Bowl. In these areas you may find very stable snow near the bottom or middle, but unstable snow near the middle or top. Be careful of what you are traveling underneath.

WEATHER: Throughout yesterday, snow showers brought about 3” of snow to the summit. Down at Hermit Lake we received only a trace. Given the temperature trends, I strongly suspect the snow that fell above the ravines is cold enough to have been moved by overnight winds. These winds came from a NNE direction and increased in speed from 40mph at 6pm to gusts in the 70mph range around midnight. Winds today will diminish slightly, forecasted to be from the N at 45-60mph. Ravine temperatures may hover around the freezing mark again today while uppermost elevations should remain below freezing.

SNOWPACK: This stretch of weather has been interesting from an avalanche forecasting perspective. Snow totals and winds do not tell the complete story of what’s taking place. The relatively warm temperatures are one prominent factor keeping things interesting. With the ravine temps hovering around freezing, the ability of the new snow to move toward better stability is much greater than is typical in mid-winter; this is happening in the absence of the usual springtime melt-freeze cycles. I expect that this process is underway, especially within the 3” of snow that came in the week prior to yesterday, we do not have enough evidence yet of stable snow to forecast Low avalanche danger. This means that your ability to carefully assess the snowpack will be critical to your decision of whether or not to travel on a certain slope today. You should also be paying attention to the amount of solar energy penetrating the snowpack. This can help stabilize some thinner slabs, but if it doesn’t reach deeply enough in thicker slabs, it might only serve to weaken the uppermost snow, which makes human triggered avalanches more likely.

If you want to avoid much of the new loading hazard, stay away from the right and center of Tuckerman. Hillman’s Highway and the Lower Snowfields have much less risk and have been providing enjoyable skiing for many people in the last few days. Remember though that Low avalanche danger does not mean “No Danger.” Stay alert for isolated slabs and be wary of traveling in the avalanche path below others.

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 Mount Washington Volunteer Ski Patrol, or the AMC at the Pinkham Notch Visitor Center and Hermit Lake.
  • Posted 8:15 a.m., Tuesday, April 28, 2015. A new advisory will be issued tomorrow.

Jeff Lane, Snow Ranger
USDA Forest Service
White Mountain National Forest
(603) 466-2713