Posted 8:00a.m., Monday, January 10, 2011
Tuckerman Ravine has Moderate and Low avalanche danger today. The Chute, Center Bowl, Lip, Sluice, Right Gully and Lobster Claw have Moderate avalanche danger. Natural avalanches are unlikely and human triggered avalanches are possible. All other forecast areas in Tuckerman as well as all those in Huntington have Low avalanche danger. In these areas natural and human triggered avalanches are unlikely.
Upslope snow showers provided the mountain with a little facelift yesterday but it wasn’t a whole lot to brag about and we struggled to meet the forecasted ratings in many areas. The Observatory recorded just under one inch (2.5cm) of new snow but it seemed like we picked up more than that at Hermit Lake. Measurements at our snowplots below the ravines don’t provide useful information because the winds were howling all day long and significant drifting occurred. Blowing snow has dominated the alpine area for the past 24 hours with WNW winds averaging around 70mph (113kph). During these conditions snow was transported across the mountain and deposited as windslab in areas with adequate protection from the wind. The most protected spots probably held onto some of this windslab but new snow was definitely fighting against the odds. The bed surface onto which the snow was trying to cling is a melt-freeze layer that could hardly be called a crust (it basically IS our snowpack). The New Year’s Eve warm-up did a wonderful job of consolidating the snowpack but when the mercury plummeted immediately after, everything locked up in diamond hard fashion. The slick surface that formed as a result has repelled most efforts for bonding and what we really need to make things stick is a good dumping of heavy snow after the surface has warmed up. Unfortunately the snow that we’ve received in recent days has been all very light density with close to twenty parts air for every one part of water. This snow might be great for skiing when there’s a base underneath but it’s no good for sticking to New England bulletproof! In areas that are rated Moderate I would expect to find a mixture of stiff hard slab and windpacked snow that has had its energy blasted out of it. Soft slab may also exist in the most protected locations.
The same strong winds that transported snow into sheltered lee areas also scoured and stripped snow out of those spots that lack adequate protection from WNW winds. The old surface is visible in many areas including most of Huntington Ravine and provides the best opportunities for travel on a stable surface. The larger issue in these areas is one of long sliding falls. Self arrest needs to instinctive and immediate when traveling in steep terrain under such conditions. If a slide isn’t stopped at once you may take a long and unenjoyable ride down to the bottom of the ravine. Make sure that you have the skills and equipment to travel safely in steep terrain.
We checked out the Sherburne Ski Trail yesterday after a usually reliable source called the skiing “not bad.” I don’t know what he was thinking. There is decent coverage for the top third but the surface conditions are choppy hardpack with occasional drifting. Below that there is more water ice and exposed vegetation then there is snow. I would dare say that the lower half is unskiable for the large part even if you’re using your worst enemy’s skis.
- 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.
- This advisory expires at midnight. A new advisory will be issued tomorrow.
Justin Preisendorfer, Snow Ranger
USDA Forest Service
White Mountain National Forest
(603) 466-2713 TTY (603) 466-2856