Jeff and I went looking for pockets of instability in Tuckerman Ravine on February 5 when we had a Low hazard rating. Just after shooting the video, we climbed around, considering overhead hazards, looking and finding pockets of instability that could be triggered by a person on foot. We cut the legs out from under a 45 degree slope and triggered 3 small slabs 10-20 feet across. Below is the text from the morning rating. I bring this up to point out that Low Hazard doesn’t mean No Hazard. The videos below show the easy hand shears and the nature of the layers on that day.
“Our avalanche danger is on the Low end of Low throughout the forecast areas except for in the very few places where snow managed to accumulate. The most notable of these locations is the Lip and below the main waterfall in the Center Headwall area where undulating pillows of snow are scattered around between thin spots of hard refrozen crust. The fresh pillows are still shallow and wind affected enough that it remains in the Low hazard category but I would exercise solid routefinding skills while traveling through these areas, in part primarily due to the potential for hidden ice, but also to avoid areas with potentially unstable snow.”
Tuckerman has LOW and MODERATE avalanche danger. The Sluice, Lip, Center Bowl and the 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. All other forecast areas have Low avalanche danger. Natural and human triggered avalanches are unlikely except in isolated terrain features.
Huntington has LOW and MODERATE avalanche danger. Central, Pinnacle and Odell have Moderate avalanche danger. Natural avalanches are unlikely and human triggered avalanches are possible. Evaluate snow and terrain carefully to identify features of concern. All other forecast areas have Low avalanche danger. Natural and human triggered avalanches are unlikely except in isolated terrain features.
I don’t like sounding like a broken record stating the obvious but here goes anyway. The slow inch or two of snow continue to bring small amounts of precipitation to the mountain through upslope snow events. The orographic lifting on the western side of the mountain has brought us at least a little bit of snow everyday this month. Before you get too excited and I lose perspective, the 6” (15cm) over the past 6 days has done very little to change our sad looking boney winter scene. Although generally our snowpack has been quite stable it is time to start paying more attention travelling in avalanche terrain. Yesterday our field time had us on mostly hard old icy surfaces and some new snow. Pockets of fresh slab between boot top and up to the knee in depth were found in a few strong lee areas high under Tuckerman’s Headwall ice. The pocket like nature from the Sluice over to the Chute fell within the ‘Low’ rating definition, but hedging towards Moderate particularly in the Lip area. Today, with snow every hour since midnight and winds picking up to hurricane force from the W and NW we feel it’s necessary to move a handful of areas to Moderate. The Lip followed by the Center Bowl will reach the rating first with some outliers really struggling to get there, but will, at some point today. This is particularly true in Huntington where old hard surfaces dominate. Central should reach Moderate first with Pinnacle and Odell lingering behind staying at Low for most of the day.
The bull’s eye data: Light snow will fall today bringing up to 2” (5cm) of new snow. This will load into E and SE facing aspects on a building wind climbing to 75+ this afternoon. This wind will also bring some leftover snow from above treeline into our start zones. Therefore we have a slowly increasing avalanche danger trend in some direct lee areas that harbor our largest bed surfaces, particularly in Tuckerman. Areas posted at Low may build some smaller pockets of new snow that can be avoided, but realize they do exist in isolated terrain features.
Surfaces are still quick hard and icy in most locations so the adage of “no fall conditions” is still of paramount importance. Self-arrest after the first second being unlikely coupled with boney rock filled terrain makes a fall in angle terrain a very bad event. As always, possessing crampons (not microspikes), an ice ax and the skills to use them are vitally important.
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 8:43a.m. 2-06-2013. A new advisory will be issued tomorrow.
Christopher Joosen, Snow Ranger
USDA Forest Service
White Mountain National Forest
(603) 466-2713 TTY (603) 466-2856