Avalanche Advisory for Tuesday, April 1, 2014

This advisory expires at 12:00 midnight.

Tuckerman Ravine has Moderate and Low avalanche danger. The Sluice, Lip, Center Bowl, Chute, Left Gully, and Hillman’s have Moderate avalanche danger. Natural avalanches are unlikely and human triggered avalanches are possible. All other forecast areas have Low avalanche danger. Natural and human triggered avalanches are unlikely.

Huntington Ravine has Moderate and Low avalanche danger. Central Gully has Moderate danger. Natural avalanches are unlikely and human triggered avalanches are possible. All other forecast areas have Low avalanche danger. Natural and human triggered avalanches are unlikely except in isolated terrain features.

AVALANCHE PROBLEMS: Today’s danger ratings are not the type of danger where you just look at the slat boards and keep moving. Read on for more details.

Problem #1 is persistent slab. The greatest threat from this will be in the Moderate rated areas of Tuckerman that have a SE aspect, but you should be assessing for this threat wherever you travel. Remember that a Low rating means avalanches are unlikely, which is not the same as saying impossible. This threat will increase during the day as the existing crust layer loses its strength.

Problem #2 is loose wet avalanches. These are sometimes called sluffs and tend to be smaller and slower moving than slab avalanches. However, they can easily sweep you off your feet, which can have serious consequences depending on the terrain. South-facing slopes will be the prime location for this threat.

WEATHER: Today might be one of the first days where we truly get spring-like weather conditions. Diminishing winds, warm temps, and ample sunshine should make it a pleasant day to be in the mountains. Don’t take my word for it though, you should always check the summits forecast before heading out.

SNOWPACK: The snowpack on the entire mountain is encased is a lovely crust this morning. This was formed by warm temperatures late Saturday followed by a freeze. We do not believe this warmth penetrated deeply enough into the snowpack to negate all the potential weak layers in the sub-surface snowpack. However, the crust currently adds a lot of strength to the snowpack. Today, this crust will be subjected to warmth and sunshine, which should cook through the crustiness, especially on south and east facing slopes. As this crust is warmed, it will lose its strength. The two most notable effects of this are that the skiing and riding surface will improve tremendously and that any underlying weak layers will be more susceptible to impacts from people traveling over them. More appealing conditions coupled with increasing hazard should make you think twice. Take the time to assess the snowpack, be aware of changing conditions, and expect lots of spatial variability.

The persistent slab problem responsible for the recent large avalanche on the summit cone may exist in a variety of locations in Tuckerman and Huntington. In some locations, this layer was affected by avalanche activity already and so poses less of a threat. This includes some portions of the Lip and Center Bowl but not all of it. The Sluice and Chute are locations where you may find this problem, as well as Central Gully in Huntington. Thankfully, Right Gully and Lobster Claw had very little snow at the time when this layer developed, so I do not think it will play a prominent role in avalanche hazard there. Hillman’s and Left Gully may also have this issue, but will be slower to warm today and therefore it’s less likely that you’ll be able to impact the layer, but if you do the outcome would be a large slab release.

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 or the staff at Hermit Lake Shelters or Pinkham Notch Visitor Center.
  • Posted 8:30 a.m. 04-01-2014. A new advisory will be issued tomorrow.

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

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