Avalanche Advisory for Tuckerman and Huntington Ravines Posted: 8:22 a.m., Friday, January 18, 2008 Tuckerman Ravine and Huntington Ravine have HIGH avalanche danger today. Natural avalanches and human triggered avalanches are likely. Travel in avalanche terrain is not recommended. The only exception to this is the Little Headwall which is dominated by open water and has Low avalanche danger. Natural avalanches are very unlikely and human triggered avalanches are unlikely except in isolated pockets. Normal caution is advised. This morning we're treated to a few inches of new snow on the mountain and more is expected through the first part of the day. 3-4" (8-10cm) cover the lower half of the mountain this morning and forecasts are calling for just a couple more inches before the snow guns shut down. Although it's not quite what we want to hear, some reports are calling for a brief changeover to freezing rain by late morning. I'll have mine without the junk please! Although the falling snow is capturing our attention now, by midday I think all eyes will be on the wind. Summit winds are currently blowing out of the S at 50mph (81kph) but change is in store. As the hours roll by we expect to see the wind shift to the W and then toward the NW for the transition to darkness. This clockwise wind shift will be accompanied by an increase in wind speeds as gusts first push 70mph (113kph) and then make their bid for triple digits F (161kph). Even if we do develop a thin crust from a period of freezing rain you can expect the winds to tear it apart like jackals on a carcass. In addition to today's new accumulation, there's probably some snow remaining from the beginning of the week that will be available for transport once we reach speeds in excess of 60mph (97kph). When driven down into the ravines by the merciless wind, transported snow will be largely falling on slick old surface. This crusty layer has not shown great promise in selecting a long-term neighbor so we'll have to wait and see how this new suitor fairs in the bonding process. Due to the changing nature of the winds you should expect N aspects to be the dominant concern of the morning followed by E and SE aspects later in the day. As winds ramp up you can also expect slabs to be formed with increasing densities. This has caused us to pull out the High slats for the day with terrain, weather and snowpack all coming together to form an opus of avalanche activity. The weather forecast for the holiday weekend is still being sorted out but right now it looks like we'll be seeing some chilly air to delight the masses. Scattered snow showers are expected to add some winter ambiance but no big powder dump is forecasted for your extra day away from the office. Keep your fingers crossed and your thermos full of cocoa. Although the new snow is trying to cover it up, the hard old surface is poking through in places. Until it has vanished you will need crampons, an ice axe and solid self arrest skills to travel safely in steep terrain. This includes travel on the Lion Head Winter Route. The Sherburne Ski Trail has some new snow to make you temporarily forget about the solid base hidden below. Please Remember: o It is impossible to accurately predict natural events, such as avalanches, in every instance. This Advisory is one tool to help you make your own decisions in avalanche terrain. It should be used along with safe travel techniques, snow stability assessments, an understanding of weather's effect on the snowpack, and proficiency in avalanche rescue. o You should obtain the latest weather forecast before heading into the mountains. Anticipate a changing avalanche danger when actual weather differs from the National Weather Service forecast. o For more information, contact the U.S. Forest Service Snow Rangers or the AMC at Pinkham Notch Visitor Center or Hermit Lake Shelters or the HMC caretaker at the Harvard Cabin. This advisory will expire at midnight. Justin Preisendorfer, Snow Ranger USDA Forest Service White Mountain National Forest