PWDR8S
04-19-2007, 12:15 PM
Avalanche Advisory for Tuckerman and Huntington Ravines
Posted: 8:54 a.m., Thursday, April 19, 2007
Tuckerman Ravine and Huntington Ravine have CONSIDERABLE avalanche danger today. Natural avalanches are possible and human triggered avalanches are probable. Be increasingly cautious in steeper terrain. There are two exceptions to this rating. Hillman's Highway has Moderate avalanche danger. Natural avalanches are unlikely and human triggered avalanches are possible. Use caution in steeper terrain. The Little Headwall has Low avalanche danger. Natural avalanches are very unlikely and human triggered avalanches are unlikely except in isolated pockets. Normal caution is advised. As luck will have it, this morning we're greeted by bluebird skies and clear views of a mountain cloaked in its full winter regalia with new windslab, fracture lines, debris piles, cornices, and wind hammered snow. Any areas that aren't sporting one of these adornments are generally covered in a thick blanket of heavy snow. Temperatures dropped enough overnight to produce a thick crust at the base of the ravines and this likely extends up toward the start zones as well. This crust does help with stability but it will likely be baked away by the end of the day. As this happens we will begin to have more concern with avalanche activity especially on the south-facing slopes baking in the sun. Tuckerman is showing much more stabilizing wind effect than Huntington today which is the opposite of our norm. Then again we're not used to 35"(89cm)of snow with sustained 100+mph(161+kph) East winds like we saw all Tuesday. The start zones in Tucks show more scouring and windsculpting than areas farther down and Hillman's is rated at the upper end of Moderate due to the extent of this wind effect.
One of the major concerns that we're watching and planning to investigate further today is the potential for warmth-induced avalanching. Throughout the storm cycle we received snow densities that would make Utah skiers write off the storm as unskiable. After we calculated the figures the average density works out to somewhere around 21%! Although some was lighter and some heavier, there is undoubtedly a tremendous amount of weight and water that has been introduced into our snowpack. As we push through the next couple of days we'll be closely watching the freeze-thaw cycles that will help move the snowpack toward an isothermic and more stable state. Until we repeat the melt-freeze process a few times we have concerns about freewater in the snowpack saturating the less dense layers or running along the topside of any less permeable layers such as buried crusts. If you're out there in the sun and punching knee-deep in heavy wet snow red flags should be waving in your mind. Mt Washington is generally considered to have a direct action avalanche regime with most natural avalanches occuring during or immediately after a storm. Lingering instabilities and delayed natural releases are not the norm here though they do happen and can catch you sleeping if you don't stay tuned in to all the relevant factors. Keep checking the advisory and Friday's weekend update if you're planning on heading this way in the near future. We expect to be able to lower the ratings in some areas after more field investigation but some stability concerns may persist into the weekend.
The Lion Head Winter Route is open, however, avalanche issues may arise as anchors become buried. As always, be prepared to make your own assessments of the snow if you plan on traveling on this route. It is also a steep and challenging route. Crampons, an ice axe, and the ability to properly use this equipment are necessary for safe travel on this route. You will find snowshoes or skis mandatory for traveling off the beaten path. This includes the Lion Head trail. The Little Headwall has undermined snow. Be very cautions if you decide to travel through this area.
Please Remember: • 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.
• 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.
• For more information, contact the U.S. Forest Service Snow Rangers or the AMC at Pinkham Notch Visitor Center or Hermit Lake Shelters. This advisory will expire at midnight.
Justin Preisendorfer, Snow Ranger
USDA Forest Service
White Mountain National Forest
(603) 466-2713 TTY (603) 466-2856
This is the Official Tuckerman Ravine website. Occasionally the remoteness of Tuckerman Ravine, weather, or communication problems prevent the website from being updated immediately. Check the date, and if it is not the most recent, you can also call the National Forest Service's 24 hour avalanche hotline at (603) 466-2713 (ext. 4) Avalanche Advisory Archives (http://www.tuckerman.org/avalanche/archives/).
United States Avalanche Danger Descriptions (http://www.tuckerman.org/avalanche/scale.htm).
Échelle Canadienne de risque d’avalanche (http://www.tuckerman.org/avalanche/scalefrancais.htm).
Back to the Tuckerman Ravine Home Page (http://www.tuckerman.org/)
Posted: 8:54 a.m., Thursday, April 19, 2007
Tuckerman Ravine and Huntington Ravine have CONSIDERABLE avalanche danger today. Natural avalanches are possible and human triggered avalanches are probable. Be increasingly cautious in steeper terrain. There are two exceptions to this rating. Hillman's Highway has Moderate avalanche danger. Natural avalanches are unlikely and human triggered avalanches are possible. Use caution in steeper terrain. The Little Headwall has Low avalanche danger. Natural avalanches are very unlikely and human triggered avalanches are unlikely except in isolated pockets. Normal caution is advised. As luck will have it, this morning we're greeted by bluebird skies and clear views of a mountain cloaked in its full winter regalia with new windslab, fracture lines, debris piles, cornices, and wind hammered snow. Any areas that aren't sporting one of these adornments are generally covered in a thick blanket of heavy snow. Temperatures dropped enough overnight to produce a thick crust at the base of the ravines and this likely extends up toward the start zones as well. This crust does help with stability but it will likely be baked away by the end of the day. As this happens we will begin to have more concern with avalanche activity especially on the south-facing slopes baking in the sun. Tuckerman is showing much more stabilizing wind effect than Huntington today which is the opposite of our norm. Then again we're not used to 35"(89cm)of snow with sustained 100+mph(161+kph) East winds like we saw all Tuesday. The start zones in Tucks show more scouring and windsculpting than areas farther down and Hillman's is rated at the upper end of Moderate due to the extent of this wind effect.
One of the major concerns that we're watching and planning to investigate further today is the potential for warmth-induced avalanching. Throughout the storm cycle we received snow densities that would make Utah skiers write off the storm as unskiable. After we calculated the figures the average density works out to somewhere around 21%! Although some was lighter and some heavier, there is undoubtedly a tremendous amount of weight and water that has been introduced into our snowpack. As we push through the next couple of days we'll be closely watching the freeze-thaw cycles that will help move the snowpack toward an isothermic and more stable state. Until we repeat the melt-freeze process a few times we have concerns about freewater in the snowpack saturating the less dense layers or running along the topside of any less permeable layers such as buried crusts. If you're out there in the sun and punching knee-deep in heavy wet snow red flags should be waving in your mind. Mt Washington is generally considered to have a direct action avalanche regime with most natural avalanches occuring during or immediately after a storm. Lingering instabilities and delayed natural releases are not the norm here though they do happen and can catch you sleeping if you don't stay tuned in to all the relevant factors. Keep checking the advisory and Friday's weekend update if you're planning on heading this way in the near future. We expect to be able to lower the ratings in some areas after more field investigation but some stability concerns may persist into the weekend.
The Lion Head Winter Route is open, however, avalanche issues may arise as anchors become buried. As always, be prepared to make your own assessments of the snow if you plan on traveling on this route. It is also a steep and challenging route. Crampons, an ice axe, and the ability to properly use this equipment are necessary for safe travel on this route. You will find snowshoes or skis mandatory for traveling off the beaten path. This includes the Lion Head trail. The Little Headwall has undermined snow. Be very cautions if you decide to travel through this area.
Please Remember: • 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.
• 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.
• For more information, contact the U.S. Forest Service Snow Rangers or the AMC at Pinkham Notch Visitor Center or Hermit Lake Shelters. This advisory will expire at midnight.
Justin Preisendorfer, Snow Ranger
USDA Forest Service
White Mountain National Forest
(603) 466-2713 TTY (603) 466-2856
This is the Official Tuckerman Ravine website. Occasionally the remoteness of Tuckerman Ravine, weather, or communication problems prevent the website from being updated immediately. Check the date, and if it is not the most recent, you can also call the National Forest Service's 24 hour avalanche hotline at (603) 466-2713 (ext. 4) Avalanche Advisory Archives (http://www.tuckerman.org/avalanche/archives/).
United States Avalanche Danger Descriptions (http://www.tuckerman.org/avalanche/scale.htm).
Échelle Canadienne de risque d’avalanche (http://www.tuckerman.org/avalanche/scalefrancais.htm).
Back to the Tuckerman Ravine Home Page (http://www.tuckerman.org/)