Avalanche Advisory for Thursday 4-18-2013

This advisory expires at 12:00 midnight.

Tuckerman and Huntington Ravines have LOW avalanche danger. Natural and human triggered avalanches are unlikely.

As far as avalanche danger is concerned, we’re about as low as you can go right now. The reason for this is the rain we had earlier this week, which was followed by a light overnight freeze, and then a warm day yesterday and a freeze last night. This warm-cold cycle has a few names, such as a corn cycle or melt-freeze cycle, but the impact is the same. It helps to eliminate the layering in the snowpack, which leads to very good stability. Since the avalanche problem isn’t going to occupy precious and finite mental energies, we want you to put your available resources into the other ways you can stay safe today:

  1. Be aware of falling ice. The annual process where all the ice that formed during the winter crashes down into the Bowl has begun. Rain and warm temperatures make the problem worse.  We know it will happen, the question is exactly when. It’s your job to be aware of the hazard and have a plan in mind for what you’ll do when you see that dishwasher sized chunk of ice rocketing at you. Lunch Rocks and the floor of the ravine are directly in the path of falling ice.
  2. Stay clear of crevasses. We have yet to see much of this problem yet, but they have begun to form in the upper Lip area as well as a couple other isolated location. Warm temperatures will cause the snowpack to creep downslope, which opens up deep cracks in the snowpack. These grow large enough for a climber or skier to fall into, and many times they can’t be seen from above them. The best way to know about this hazard is to climb up your intended decent route. If you see cracks in the snow, stay well away from the edges.
  3. Avoid undermined snow and the Little Headwall. Right now this issue is mostly found in the streambed leading out of the ravine and on the Little Headwall. The Little Headwall has a large open hole in the steepest part of the route.  This hole has grown in the last couple days, and is threatening to collapse further. The same can be said for the snow bridges in the streambed above the Little Headwall. Yesterday I said to use caution if you decide to ski out from the Bowl; after seeing what I saw yesterday, I cannot recommend skiing out from the bowl. Hiking out on the trail is a faster and safer option. If you go this route and need to take off your skis or  board, you will likely encounter nasty postholing conditions.

The weather forecast for the next few days is an interesting one. If you’re planning a trip to the ravine for the weekend, for fun or for the Tuckerman Inferno race, I’d encourage you to closely monitor the higher summits forecasts put out by the Observatory and the NWS. We’re expecting tropical temperatures Friday with warm monsoon-like conditions late day and overnight, followed by a cold front that will cause temperatures to plummet during the day Saturday. I don’t foresee strong clearing conditions on the mountain until Sunday and Monday. It’s a good weekend to put away the small backpack in favor of the larger one so you can carry enough extra dry layers and comfort foods.

Please Remember:

  • 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 at 8:00 a.m., April 18, 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

2013-04-18 Printable