Avalanche Advisory for Friday April 18, 2014

This Advisory expires at midnight.

Tuckerman Ravine has Low avalanche danger. Natural and human triggered avalanches are unlikely except in isolated terrain features. These pockets do exist particularly from the Lip through the Center Bowl. Other secondary pockets exist in other locations such as in the Sluice, on the traverse between the Sluice and the Lip, etc. It is important to understand there is still potential to trigger a pocket from midweek’s snow, albeit isolated.

Huntington Ravine is under a General Advisory. You will need to do your own snow stability assessments when traveling in avalanche terrain in Huntington. A danger of falling ice exists, and will persist until it all comes down.

AVALANCHE PROBLEM: Wind deposited snow across the Center Bowl, and especially in the Lip area, that occurred on Wednesday is still the primary concern. These Wind Slabs stabilized a bit yesterday as temperature flirted with the freezing mark under bright sun. Higher temperatures in avalanche terrain today, perhaps close to 40F, will likely move cold wind slab issues towards a Wet Loose and thin Wet Slab concern.

WEATHER: Clear conditions and good 100 mile visibility with temperatures just below freezing made for a nice “winter” day on Thursday. Today, summit temperatures should break the freezing mark while increasing clouds start to knock down solar gain influence this afternoon. Winds from the S will move to the SW and increase to 40+mph (64kph). Looking forward, snow showers overnight and colder air will be in place tomorrow, but we’ll discuss that more in this afternoon’s Weekend Update.

SNOWPACK: +/-2” of rain on Tuesday followed by sub-zeroF temperatures created a bomber concrete snowpack by Wednesday that would have taken a trigger of planetary proportions to cause avalanches. A couple of inches of snow that fell since then are the problem now that Frank discussed yesterday, and I mention above. Slabs are scattered around primarily in the Center Bowl and Lip and are not to be walked into blindly, but don’t quite make into the Moderate rating. This is due to their overall lack of widespread continuity, size in the steepest terrain, the snow surfaces texture allowing good adhesion, as well are the generally roughness of the surfaces caused by the weekend traffic. Rain did knock down the size of bumps in the Lip, etc. but all these types of features are assisting in keeping new snow in place. Again, have an eye open for instability and do your stability tests to have good information to help your choices. A prudent and thoughtful user can avoid problems with some flexibility.

Additionally, be sure to consider new snow may be covering the beginning of developing crevasses and holes. Some of these drifts may be obscuring possible deep slots that opened during recent heavy rain and warm temperatures. You are most likely to find these on steep snow slopes beneath buttresses of rock or ice in the Headwall/Lip and Sluice areas. Be aware of the potential to punch through into these slots. The main waterfall hole, marking the Lip/Center Bowl boundary, opened during the rain storm, but some thin ice and snow is now concealing the hazard from view. The Open Book waterfall hole in the fall line of the Lip, 2/3rds the way down towards the floor, could make a sliding fall extremely consequential. Choose your line carefully!

OTHER HAZARDS: 1. Micro-spikes and other creeper style traction devices may be helpful on some lower angle trails, but they simply are not adequate for steep terrain! Be prepared for steep, firm snow and fast, icy surfaces. A fall on steep terrain today on the old surface would be next to impossible to self-arrest. Don’t fall especially above a crevasse or streambed. 2. Warm conditions will return the ice fall menace! The Sluice ice, behind Lunch Rocks, make this a horrible place to sit. Ice fall across the Lip through the Center Bowl is also looming waiting to be heated. Next to sliding falls this has been out #2 injury maker over time. Do not linger in their runouts! 3. Recent rain and warm weather really melted out snow spanning streams like the one that flows out of Tuckerman. With our deep snowpack, the distance from snow surface to rushing streambed below could make it difficult to climb out of some of the holes should you fall in. 4. The Sherburne ski trail is what you would expect after 2″ of rain followed by freezing temperatures. You can still make it to the parking lot but expect detours around ice, large bumps, bare spots and open water drainages.

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 0815. 4-18-2014. A new advisory will be issued tomorrow.

Christopher Joosen, USFS Snow Ranger.

2014-04-18 Print