Avalanche Advisory for Friday, January 18, 2013

Tuckerman Ravine has Moderate and Low avalanche danger. Right Gully, the Sluice, Lip, Center Bowl, and Chute have Moderate avalanche danger. Natural avalanches are unlikely and human triggered avalanches are possible. Evaluate snow and terrain carefully to identify features of concern. Lobster Claw, Left Gully, Hillman’s Highway, Lower Snowfields, and the Little Headwall have Low avalanche danger. Natural and human triggered avalanches are unlikely except in isolated terrain features.

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

In the last two days, Mt. Washington has received just shy of 6” (15cm) of new snow. 3.6” (9cm) of this fell yesterday, which was greater than the forecasted amounts. During this time, W and NW winds were quite strong, gusting into the 80’s and 90’s mph (130-145kph). These did a great job of moving snow around in the ravines and creating stability problems. One very lucky party was avalanched from the top of Central Gully late in the day as they climbed through this newly deposited soft slab. More details will be posted tonight on our Weekend Update section of our website and on our Search and Rescue page.

Bright blue skies this morning are allowing good visibility, though some new blowing snow is obscuring the very top of Central. This shouldn’t amount to much additional loading during the day, so this fact places the emphasis for today on the potential for human triggers. Currently, lots of old, gray snow is visible with fresh white patches of new windslab scattered around. These areas are in the lee of terrain features that often lower the windspeed enough for wind transported snow to be deposited but also in swales and other irregularities in the snowpack. Expect the usual strong degree of spatial variability as you move around today. Examples of the most windloaded locations include in Central Gully above the ice bulge, in pinch points in Odell and Yale, and all the snowfields in Tuckerman across the Lip and Center Bowl. This is not to say other areas are without hazard, so pay attention even in areas rated Low today.

Other areas to consider are the transitions from steep to flat where sluffing snow has accumulated at the base of ice and rock faces as well as at the near the tops of gullies. Given the rounded nature of our geologically elderly terrain, the tops of gullies are often less pronounced than more youthful mountains. So instead of an obvious overhanging cornice, you may encounter gradually steepening snow which has been deposited in the wind rotor created at the “edge” of the ravine. These areas are also features that you should assess very carefully and possibly avoid.

Cold temperatures last night, (-21F, -30C on the summit) have started freezing up the water running through drainage channels. I doubt that the process is complete so be on the lookout for ice dams if you brave the cold today to do an ice climb. The Little Headwall showed an open channel from top to bottom yesterday and snow is now skimmed over what is likely to be a thin veneer of ice. This condition is likely to be encountered on climbs like North, Damnation, Yale, Central ice bulge, Pinnacle…basically all the ice climbs in Huntington plus ice flows in Tuckerman.

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 8:30a.m., Friday, January 18, 2013. 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

2013-1-18 Print friendly