Posted 7:55am, Sunday, March 6, 2011
Tuckerman Ravine has High and Considerable avalanche danger. Except for the Little Headwall and Hillman’s Highway, all forecast areas of Tuckerman Ravine have High avalanche danger. Natural avalanches are likely and human triggered avalanches are very likely. Travel in avalanche terrain is not recommended. Hillman’s Highway and the Little Headwall have Considerable avalanche danger. Natural avalanches are possible and human triggered avalanches are likely.
All forecast areas of Huntington Ravine have Considerable avalanche danger. Natural avalanches are possible and human triggered avalanches are likely.
The wild ride continues today, and it seems as though yesterday was simply a warm-up exercise before the main event today and tonight. Today we’re looking at copious amounts of rain falling in avalanche terrain. One of the first rules of thumb you might have learned is “when it rains in avalanche terrain, go home.” Who am I to tell you where to go when it’s raining? Honestly, you can go wherever you’d like, but my personal and professional advice would be to stay away from avalanche terrain today. Temperatures in the ravines have been above freezing since yesterday, and rain has already added to the amount of free water currently percolating downward into the snowpack. Hermit Lake has received about an inch of water since yesterday morning. Today you can expect more steady rain and perhaps some sleet and freezing rain this afternoon as temperatures begin to fall. Additional liquid equivalents in the range of 0.5″ to 1″ (1.25-2.5cm) can be expected before we see steady snow.
All of this water seeping down into the snowpack leads us to believe avalanches are likely in many of our forecast areas. The areas we are most concerned about had a deep and multi-layered upper snowpack. Many of the interfaces between these layers have the potential to fail and produce avalanches. Prior to the wetting, the areas posted at Considerable had been more scoured out and beaten down by strong winds after the last snowfall. While the potential for natural avalanches in these areas falls below our threshold for calling them “likely,” we do believe there is a possibility for heavy wet slides to run down the gullies. The overall danger rating may be less, but it is still a dangerous situation that you will have little control over or ability to predict. The Little Headwall is posted Considerable, but the true danger here is due to problems that may be created by the stream beneath it swelling and either bursting onto the top of the snow or undermining it from below. It would be best to wait a day before heading into this area.
Ok, so all this nasty weather does have a silver lining…or perhaps I should call it a white lining. Later this evening precipitation will change back to snow, with the mountains potentially receiving over a foot of new snow before clearing on Monday. This is welcome news, but you should also consider how it might affect travel around the mountain. Today’s rain and warmth will make off-trail travel a posthole nightmare. The heavy blanket of snow will act as insulation and keep snowpack temperatures warm, allowing the nightmare to continue for quite a while. Plan on bringing your fattest skis or your biggest snowshoes if you’re heading off of the most well-traveled paths.
- 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.
Jeff Lane, Snow Ranger
USDA Forest Service
White Mountain National Forest
(603) 466-2713 TTY (603) 466-2856