Posted 8:00 a.m., Wednesday, March 30, 2011
Tuckerman Ravine has Moderate avalanche danger. Natural avalanches are unlikely and human-triggered avalanches are possible. The only exceptions to this rating are the Little Headwall and Left Gully which have Low avalanche danger. Natural and human-triggered avalanches are unlikely in these areas. Watch for unstable snow on isolated terrain features.
All forecast areas in Huntington Ravine have Low avalanche danger. Natural and human-triggered avalanches are unlikely. Watch for unstable snow on isolated terrain features.
It has been a dynamic week with more weather expected to keep the show going. Today and tomorrow morning are forecasted to bring a welcome lull in the active weather pattern before a Nor’easter impacts the region on Thursday night and Friday. Today’s stability concerns are lingering wind slabs from last weeks 11.8″ (30 cm) of snow and a prolonged period of winter weather punctuated by relentless winds. The mountain has been punishing lately and avalanche activity has been abundant. The last storm, which was actually an unforecasted up slope snow event, produced our largest avalanche of the season in Tuckerman and numerous avalanches in terrain that hasn’t really had avalanche activity this season. Natural avalanche activity calmed down on Sunday but we have had two natural avalanches since then that we know of. The most recent of these occurred on Monday night when a sluff from the Duchess triggered a small slab in the Lower Snowfields. Trace amounts of snow have fallen over the past two days which may have formed some softer slabs in strong lee areas of NW winds. Of all the stability issues today, these will be the easiest to trigger but of less consequence than the hard slab that dominates Tuckerman. The hard slab provides good bridging over weaker layers below and it could be challenging to trigger an avalanche. If someone were to find a “sweet spot” that causes failure and fracture in the hard slab, expect a nasty avalanche to ensue. Strong and sustained winds have created a mosaic of snow conditions that will require you to stay alert to changing conditions. In Huntington, this mosaic exists but isn’t as complex as Tuckerman. For the most part, Huntington has been pounded into a stable state by recent winds. Tuckerman offers some options for the avalanche savvy traveler and clearing conditions should make it easier to make sense of what is going on.
We look forward to taking advantage of the clearing trend to better evaluate the current avalanche issues. Expect similar stability ratings tomorrow with potential for some areas posted at Moderate to move down to Low. As mentioned, we are starting to have more confidence that this next storm will bring accumulating snow to the mountains Thursday night and Friday. Expect elevated avalanche danger to spill over into the weekend. We will keep you posted on this in the coming advisories and in Friday’s weekend update to help you with your trip planning.
The Lion Head Winter Route is filling in and evidence of recent avalanche activity can be found on both sides of the route. The best line up the ridge is marked with bamboo poles. Stay on this path to avoid the more significant avalanche terrain on either side.
Saturday night will be the last night the Harvard Cabin will be open this season. After that, the only place you can camp on the east side of Mt. Washington will be at Hermit Lake Shelters in Tuckerman Ravine.
- 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.
Brian Johnston, Snow Ranger
USDA Forest Service
White Mountain National Forest
(603) 466-2713 TTY (603) 466-2856