Avalanche Advisory for Tuesday, February 11, 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 Highway have Moderate danger. Natural avalanches are unlikely and human triggered avalanches are possible. All other forecast areas have Low danger. Natural and human triggered avalanches are unlikely in these locations.

All forecast areas of Huntington Ravine have Moderate avalanche danger.  Natural avalanches are unlikely and human triggered avalanches are possible. Evaluate snow and terrain carefully and identify features of concern.

AVALANCHE PROBLEMS: We’re back into a Moderate rating again today, with many forecast areas dropping down from their rating of Considerable yesterday. Wind slabs will be the primary avalanche problem. These developed over the last 48 hours from 1.5″ (4cm) of new snow being redistributed on increasing winds from the WNW. You might think this isn’t a lot of snow and you don’t really need to worry about it, but you’d only be right with half of that thought. It is not a lot of snow, but yesterday’s winds have created slabs that should definitely get your attention, especially on E-facing slopes. In addition to new windslab, we have persistent slabs lingering in a variety of locations. These older slabs may feel quite strong underfoot, but if you find and impact a weakness, a large avalanche might result. Two of the most likely areas where you’ll find this are the Center Bowl and Central Gully.

WEATHER: High pressure is trying to push its way in today, but clouds will persist at least for the morning thanks to a cold front crossing the region. Winds today may be able to keep some blowing snow in the air. As mentioned, we received 1.5″ of new snow in the last 48 hours, winds during this time were predominantly from the WNW and increasing in speeds from 20-30mph (32-48kph) up to 50-60mph (80-97kph) where they currently sit. Due to the limited amount of recent snow available for transport, I suspect the rate of snow loading will be kept down today. If winds are able to continue finding recent snow for loading, expect ratings to hover near the border of Moderate and Considerable danger.

SNOWPACK: The biggest feature of the snowpack you should be paying attention to today is the recently formed wind slab. These will have formed with softer, lighter density snow on the bottom and heavier, denser snow on the top. This inverted, or “upside down,” snowpack structure is prone to avalanching. Though visibility is currently limited, we can expect to see these slabs having developed the most on E and ESE aspects. Areas such as the Center Bowl, Lip, and Sluice in Tuckerman and Central and Pinnacle Gullies in Huntington are good examples. Deeper into the snowpack you’ll find a smorgasbord of harder slabs ranging from P to 4F on the hand hardness scale. There may be some weak layers within these that are very difficult to detect and intensely spatially variable. All in all, today is an excellent day to carefully assess the snowpack as you move around.

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 8:00 a.m. 2-11-2014. 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

2014-02-11 print