Posted 8:50 4-2-2011
Tuckerman and Huntington Ravines have HIGH avalanche danger. Natural avalanches are LIKELY and human triggered avalanches are VERY LIKELY. Very dangerous avalanche conditions exist. Travel in avalanche terrain is not recommended. The only exceptions to this are the Lower Snowfields which has Considerable avalanche danger and the Little Headwall which has Moderate avalanche danger.
The summit picked up 12” (30cm) while we recorded about 10” (25cm) down at Hermit Lake. During this snowfall winds have come from numerous points on the compass rose beginning from the SE through the E and to the N by around midnight. Since then winds have settled into their favorite groove from the NW and rapidly increased with very brief spikes in velocity. Winds were sustained between 70 and 80 mph peaking briefly at over 100 mph (160 mph). These speeds collapsed just as fast, falling down to 55-65mph where they currently sit, but are expected to rise a bit through the morning before subsiding again this afternoon gusting to 70mph. The summit crew reported very large drifts and I have no doubt that although a lot of snow has moved already early this morning it will continue and load additional snow into the Ravines through the day. In addition the Observatory is forecasting up to an additional 3” (7.5cm) of snow as upslope energy continues to produce precipitation for the mountains. If this plays out the storm total would be close to 15” (38cm).
Runout paths have filled in through the season so avalanches from this storm may very well run farther than they have yet this season. Many of these runout paths criss-cross each other in both Ravines so no place would be considered a safe to be therefore travel in avalanche terrain is not recommended. Two areas posted below the High rating today are the Little Headwall at Moderate and the Lower Snowfields at Considerable. The Little Headwall’s hazard will decrease rapidly with some skier traffic, but the initial users should exercise some caution realizing that a skier triggered avalanche is possible even though this forecast area is quite small and not too steep. Skiers and riders may start to move into the Lower Snowfields which have some strong lee pockets to be cautious about and make good stability assessments before jumping in blindly. Our main concern for this forecast area are the larger snowfields that exist under the Duchess. Sluffing or a slab avalanche from the Duchess could trigger a slab in the Lower Snowfields, so although concerns exist towards the Little Headwall side of the forecast area its risk is slightly lower.
Summiteers have 2 main hazards to contemplate, the avalanche potential on the Lion Head Winter route and weather conditions above treeline bringing visibility close to zero at times. I’ll focus on the avalanche issue. Although the trail markers and bamboo poles designate the safest line through this area it is not without risk particularly during a storm and loading event like today. Last weekend’s storm saw avalanche activity as little as 100ft from the route. It is important to have good avalanche assessment skills to make smart well informed choices. It will likely change through the day filling in footprints even if it sees a number of users. Be very aware of anyone above you that could be a trigger.
The Harvard Cabin will close tomorrow so beginning Sunday night the only place to camp on the eastern side of Mount Washington is at Hermit Lake.
- 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
Christopher Joosen, Snow Ranger
USDA Forest Service
White Mountain National Forest
(603) 466-2713 TTY (603) 466-2856