This advisory expires at 12:00 midnight, February 2, 2013.
All forecast areas of Tuckerman Ravine and Huntington Ravine have Low avalanche danger today. Natural and human triggered avalanches are unlikely. Watch for unstable snow in isolated terrain features. Avalanche danger may exceed forecasted ratings late in the day.
We’re starting the weekend with Low avalanche danger across the board in both ravines. This is a result of Thursday’s heavy rain followed by a quick plunge in temperatures. Most of the exposed snow surfaces are hard, slick crust. In some isolated pockets, a small amount of new snow has been deposited on top of the crust. These are small, isolated, and not very deep, so they don’t warrant anything more than a Low rating at this time. However, we are expecting light accumulations of new snow this afternoon and into the evening. This will come with wind speeds diminishing from their current W 60-70mph (95-115kph) down to 30-45mph (50-75kph). Expect new snow to begin loading into soft slabs as soon as it starts to fall. It will take some time for these slabs to push up out of realm of Low danger, but if we get the upper end of the forecasted amounts of 1-2″ (2.5-5cm) then some areas may push into Moderate before this advisory expires at midnight. The most likely locations for this to happen are the Lip, Center Bowl, Chute, and Left Gully in Tuckerman and Central and Pinnacle in Huntington. To recap, we are currently at Low avalanche danger and will stay there for most of the day. As new snow falls, isolated pockets of unstable snow will be growing and some may push into Moderate danger.
Outside of avalanche danger, the icy crust will be a significant hazard for mountain travelers. Anyone traveling in steep terrain will need crampons and an ice axe to have any chance at protecting against the dreaded long sliding fall. Ski poles may be helpful in some cases, but they just won’t cut it for self arresting in very steep terrain. The Lion Head Winter Route is a steep route, so an axe and crampons are highly recommended.
Ice climbers in Huntington should be aware of atypical conditions for the start of February. The first thing you’ll notice is that you’ll run out of snow and ice before you reach the top of many of the climbs. If you head up for North, Damnation, Yale, or Central, expect to do some rock scrambling. You may have difficulty finding quality ice screw placements in the tops of these gullies. Ice dams are another potential problem. A quick hard freeze after a rain event does a great job of plugging drainage channels with new ice. Built up pressure is waiting for an outlet, which could happen with the swing of an ice tool or crampon. And I know this isn’t news to everyone, but remember that climbing below other parties puts you in a hazardous position.
The John Sherburne Ski Trail does have decent coverage from top to bottom still, but it is very icy and choppy. There are numerous patches of blue water ice, some exposed rocks, and some areas where slush has run over the trail.
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 7:50a.m., February 2, 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