jumpturn
04-15-2009, 07:19 AM
http://www.tuckerman.org/accident/20082009.htm
2009-04-10
http://www.tuckerman.org/photos/tucks/images/2009-04-10%20annotated%20dodges%20photo2.JPG
04-11-2009: Two climbers were involved in an avalanche accident in Tuckerman Ravine. The accident took place on a sunnier-than-expected Saturday early in the spring skiing season. The weather forecast had called for mostly cloudy skies, summit temperatures falling to 15F, and winds ranging from 25-40mph. The morning avalanche advisory discussed the snowpack staying frozen for most of the day, with the best chance of warm soft snow being on south-facing aspects. Northerly aspects were expected to remain cold and frozen through the day. DZ and TF, both athletic and experienced mountaineers, were climbing the steep snow route known as "Dodge's Drop" unroped, each with two technical ice axes and crampons. They had recently climbed Hillman’s Highway and were familiar with the terrain on the Boott Spur Ridge. The plan was to climb the route to access the hiking trails to the summit of Mt. Washington, then descend through Tuckerman Ravine.
For much of the climb, the surface conditions were refrozen springtime crust. The party reported they were enjoying the climbing conditions when on this surface. At times, they encountered small areas of newer softer snow but this surface was more difficult to climb, so they opted for the old surface when possible. Nearing the top of the climb, they encountered an isolated pocket of relatively new slab. The upper climber (DZ) reported he was unable to swing his axes through the new snow into the crust, his boots were getting full penetration when kicked into the snow, and the snow was fully supporting his weight. He stated that he decided to move left to get around the slab both for stability reasons and for the easier climbing on the crust. As he was working himself toward the edge of the slab the avalanche released.
DZ recognized what was transpiring and was able to see the fracture line propagate upwards from his feet to a point about 6-8 feet above him. The fracture then propagated outward and the slab began to slide downhill. TF was about 10 feet below and slightly to the side of DZ. He had both ice tools sunk into the snow. The initial slab, which DZ was entrained in, pulled out more snow above TF. He attempted to hold on against the force of the slab pouring over him but he was eventually pulled off his stance. Both individuals were carried downhill, and each reported being airborne at some point. DZ stated he was impressed by how much time he had during the course of the slide to figure out what to do. He said he was unsure of whether to try to self arrest or swim to stay on top. At one point he discarded one tool and attempted to self arrest with the other. He felt the pick engaging the crust, but was unable to stop himself. He also reported that during this time he saw his partner slide past him, indicating he at least managed to slow himself to some degree. The avalanche carried them over a small cliff (hence DZ reporting being airborne for "3 heartbeats") and down into a treed slope below. The compressive force of the snow impacting the slope below the cliff was quite strong; it ripped both ice axes out of TF’s hands and they both felt as though their clothes and gear were also being pulled loose. They came to rest in the trees with most of the debris though some of the debris continued to run farther downslope. Both individuals came to rest on top of the snow; no excavation was required.
The avalanche was witnessed by a crowd in the courtyard of Hermit Lake Shelter's caretaker's cabin. The commotion alerted a Snow Ranger (Jeff Lane) who saw the climbers sliding into the trees. The caretaker of the shelter site was climbing nearby in Hillman’s Highway; he established communication with the climbers who yelled to him that they were all right. The caretaker continued over to the climbers to assess their injuries more thoroughly. Meanwhile a Snow Ranger and one member of the Mount Washington Volunteer Ski Patrol headed uphill to tie in with the party. DZ suffered a small laceration on his forehead, a broken pinky finger, sprained ankle, some ligament damage in his knee, bruising on his thigh and shin, and abrasions on both elbows. The abrasions were caused by sliding on the icy crust while wearing only a synthetic t-shirt. TF reported that he lost his vision momentarily when they came to rest but regained it soon after. He also suffered multiple abrasions on both arms and hands, ligament damage in one knee, and a bruised pelvis. The climbers were escorted to the Snow Ranger cabin at Hermit Lake where they were more thoroughly assessed and treated. From here, they were transported to the parking lot in the USFS Snowcat, where they were released into their own vehicle for transportation to a local hospital.
Snowpack information: On the night of April 6, 2009 Mt. Washington received a soaking rain transitioning to mixed precipitation and snow. Total water equivalents from this event were 0.71” recorded on the summit, with 1.2” of this coming as snow. Lower on the mountain at Hermit Lake the USFS manual snowplot precip can had collected 1.45” water equivalent with 1.9” of this falling on the storm board as snow. This rain event soaked the snowpack then refroze, giving us a baseline below which there have been no stability issues. Overnight on April 8, the summit recorded 0.4” of new snow. This new snow was not sufficient to raise the avalanche danger above Low for any of the nearby forecast areas in the days following this relatively small snowfall. It’s worth noting the ability of the wind on Mt. Washington to transform seemingly insignificant snow totals into deeper slabs. One excellent example came earlier this month. On April 4, the summit recorded 0.6” new snow. The following morning USFS Snow Ranger Brian Johnston found slabs averaging 9-10” in sheltered lee areas, with one slab measuring 24” deep. Although the snowfall responsible for this avalanche was only 0.4”, winds had been able to develop deeper slabs in isolated areas. This slope has a NNE aspect, and recent weather had been warm but not sufficiently warm to create a melt freeze cycle on northerly aspects. This isolated pocket was able to remain cold and dry while similar slabs in nearby areas with different aspects had been skied numerous times without incident in the days between the snowfall and the avalanche. The fracture line from this avalanche was estimated to average 6” deep and 30-40 feet wide. The slab depth at DZ’s high point was at least 12”.
Summary: These two climbers were incredibly fortunate. This route is generally considered “no-fall” territory due to numerous rocks, cliffs, and trees in the fall line. The total vertical drop of their fall is estimated to be around 800 feet. They managed to pass through the rocky section of the fall unscathed, with the injuries being sustained only after being carried into the trees. Ironically the avalanche which caused their fall likely helped protect them from more significant injuries as they probably rode on the debris cushion to their resting point. Falling this distance with crampons on, ice tools in hand, and going over small cliffs usually concludes much worse. That they were able to walk themselves down from an incident such as this is remarkable to say the least.
From an avalanche perspective, the climbers had chosen a reasonable route. Although Dodge’s Drop is not one of the forecasted areas on the mountain it is adjacent to Hillman’s Highway which is one the 8 forecasted slopes and gullies of Tuckerman Ravine. All 8 areas were forecasted at “Low” at the time of the accident and where heavily skied without incident. Some isolated pockets of instability did exist but between skier compaction; skiers cutting up the continuity of these pockets; and solar gain baking out any fracture propagation potential they became inconsequential by late morning. Dodge’s is a northern facing slope which makes it slow to react to sunny days as it does not receive direct solar gain. Slabs on these aspects often require higher ambient air temperatures for rapid settling compared to southern facing slopes which react very quickly to solar radiation. Using an avalanche forecast issued for an adjacent slope to your intended ascent/decent as a tool is a smart use of your available resources. In addition to the forecast discussion points however always consider how your intended route might harbor different instability issues. The slab they triggered was small and isolated; if this were in a forecasted area it would be considered an “isolated pocket.” The climbers recognized the hazard when they encountered this pocket and were attempting to mitigate it as best as they could when the fracture initiated. Many valuable lessons can be learned from this event, two are offered here as they are not uncommon occurrences on Mt. Washington. First, it’s important to recognize that “Low avalanche danger” does not mean “No avalanche danger”. Isolated pockets of instability can be present under a Low rating and you should be capable of recognizing and assessing this hazard for yourself. Second, it underscores the importance of being able to assess hazards before dropping in over the top of them. In this instance, there was at least one skier known to be hiking up Hillman’s with the intention of descending Dodge’s Drop. It’s quite likely that this skier would have triggered the pocket if the climbers had not. Whether the hazard is avalanches, crevasses, undermined snow, etc., it’s always a good idea to assess for hazards before descending from above.
2009-04-11 Looking up to the top of Dodge's there is a crown line in the climber's left side.
http://www.tuckerman.org/photos/tucks/images/2009-04-11%20Fracture%20line.jpg
For the record....
2009-04-10
http://www.tuckerman.org/photos/tucks/images/2009-04-10%20annotated%20dodges%20photo2.JPG
04-11-2009: Two climbers were involved in an avalanche accident in Tuckerman Ravine. The accident took place on a sunnier-than-expected Saturday early in the spring skiing season. The weather forecast had called for mostly cloudy skies, summit temperatures falling to 15F, and winds ranging from 25-40mph. The morning avalanche advisory discussed the snowpack staying frozen for most of the day, with the best chance of warm soft snow being on south-facing aspects. Northerly aspects were expected to remain cold and frozen through the day. DZ and TF, both athletic and experienced mountaineers, were climbing the steep snow route known as "Dodge's Drop" unroped, each with two technical ice axes and crampons. They had recently climbed Hillman’s Highway and were familiar with the terrain on the Boott Spur Ridge. The plan was to climb the route to access the hiking trails to the summit of Mt. Washington, then descend through Tuckerman Ravine.
For much of the climb, the surface conditions were refrozen springtime crust. The party reported they were enjoying the climbing conditions when on this surface. At times, they encountered small areas of newer softer snow but this surface was more difficult to climb, so they opted for the old surface when possible. Nearing the top of the climb, they encountered an isolated pocket of relatively new slab. The upper climber (DZ) reported he was unable to swing his axes through the new snow into the crust, his boots were getting full penetration when kicked into the snow, and the snow was fully supporting his weight. He stated that he decided to move left to get around the slab both for stability reasons and for the easier climbing on the crust. As he was working himself toward the edge of the slab the avalanche released.
DZ recognized what was transpiring and was able to see the fracture line propagate upwards from his feet to a point about 6-8 feet above him. The fracture then propagated outward and the slab began to slide downhill. TF was about 10 feet below and slightly to the side of DZ. He had both ice tools sunk into the snow. The initial slab, which DZ was entrained in, pulled out more snow above TF. He attempted to hold on against the force of the slab pouring over him but he was eventually pulled off his stance. Both individuals were carried downhill, and each reported being airborne at some point. DZ stated he was impressed by how much time he had during the course of the slide to figure out what to do. He said he was unsure of whether to try to self arrest or swim to stay on top. At one point he discarded one tool and attempted to self arrest with the other. He felt the pick engaging the crust, but was unable to stop himself. He also reported that during this time he saw his partner slide past him, indicating he at least managed to slow himself to some degree. The avalanche carried them over a small cliff (hence DZ reporting being airborne for "3 heartbeats") and down into a treed slope below. The compressive force of the snow impacting the slope below the cliff was quite strong; it ripped both ice axes out of TF’s hands and they both felt as though their clothes and gear were also being pulled loose. They came to rest in the trees with most of the debris though some of the debris continued to run farther downslope. Both individuals came to rest on top of the snow; no excavation was required.
The avalanche was witnessed by a crowd in the courtyard of Hermit Lake Shelter's caretaker's cabin. The commotion alerted a Snow Ranger (Jeff Lane) who saw the climbers sliding into the trees. The caretaker of the shelter site was climbing nearby in Hillman’s Highway; he established communication with the climbers who yelled to him that they were all right. The caretaker continued over to the climbers to assess their injuries more thoroughly. Meanwhile a Snow Ranger and one member of the Mount Washington Volunteer Ski Patrol headed uphill to tie in with the party. DZ suffered a small laceration on his forehead, a broken pinky finger, sprained ankle, some ligament damage in his knee, bruising on his thigh and shin, and abrasions on both elbows. The abrasions were caused by sliding on the icy crust while wearing only a synthetic t-shirt. TF reported that he lost his vision momentarily when they came to rest but regained it soon after. He also suffered multiple abrasions on both arms and hands, ligament damage in one knee, and a bruised pelvis. The climbers were escorted to the Snow Ranger cabin at Hermit Lake where they were more thoroughly assessed and treated. From here, they were transported to the parking lot in the USFS Snowcat, where they were released into their own vehicle for transportation to a local hospital.
Snowpack information: On the night of April 6, 2009 Mt. Washington received a soaking rain transitioning to mixed precipitation and snow. Total water equivalents from this event were 0.71” recorded on the summit, with 1.2” of this coming as snow. Lower on the mountain at Hermit Lake the USFS manual snowplot precip can had collected 1.45” water equivalent with 1.9” of this falling on the storm board as snow. This rain event soaked the snowpack then refroze, giving us a baseline below which there have been no stability issues. Overnight on April 8, the summit recorded 0.4” of new snow. This new snow was not sufficient to raise the avalanche danger above Low for any of the nearby forecast areas in the days following this relatively small snowfall. It’s worth noting the ability of the wind on Mt. Washington to transform seemingly insignificant snow totals into deeper slabs. One excellent example came earlier this month. On April 4, the summit recorded 0.6” new snow. The following morning USFS Snow Ranger Brian Johnston found slabs averaging 9-10” in sheltered lee areas, with one slab measuring 24” deep. Although the snowfall responsible for this avalanche was only 0.4”, winds had been able to develop deeper slabs in isolated areas. This slope has a NNE aspect, and recent weather had been warm but not sufficiently warm to create a melt freeze cycle on northerly aspects. This isolated pocket was able to remain cold and dry while similar slabs in nearby areas with different aspects had been skied numerous times without incident in the days between the snowfall and the avalanche. The fracture line from this avalanche was estimated to average 6” deep and 30-40 feet wide. The slab depth at DZ’s high point was at least 12”.
Summary: These two climbers were incredibly fortunate. This route is generally considered “no-fall” territory due to numerous rocks, cliffs, and trees in the fall line. The total vertical drop of their fall is estimated to be around 800 feet. They managed to pass through the rocky section of the fall unscathed, with the injuries being sustained only after being carried into the trees. Ironically the avalanche which caused their fall likely helped protect them from more significant injuries as they probably rode on the debris cushion to their resting point. Falling this distance with crampons on, ice tools in hand, and going over small cliffs usually concludes much worse. That they were able to walk themselves down from an incident such as this is remarkable to say the least.
From an avalanche perspective, the climbers had chosen a reasonable route. Although Dodge’s Drop is not one of the forecasted areas on the mountain it is adjacent to Hillman’s Highway which is one the 8 forecasted slopes and gullies of Tuckerman Ravine. All 8 areas were forecasted at “Low” at the time of the accident and where heavily skied without incident. Some isolated pockets of instability did exist but between skier compaction; skiers cutting up the continuity of these pockets; and solar gain baking out any fracture propagation potential they became inconsequential by late morning. Dodge’s is a northern facing slope which makes it slow to react to sunny days as it does not receive direct solar gain. Slabs on these aspects often require higher ambient air temperatures for rapid settling compared to southern facing slopes which react very quickly to solar radiation. Using an avalanche forecast issued for an adjacent slope to your intended ascent/decent as a tool is a smart use of your available resources. In addition to the forecast discussion points however always consider how your intended route might harbor different instability issues. The slab they triggered was small and isolated; if this were in a forecasted area it would be considered an “isolated pocket.” The climbers recognized the hazard when they encountered this pocket and were attempting to mitigate it as best as they could when the fracture initiated. Many valuable lessons can be learned from this event, two are offered here as they are not uncommon occurrences on Mt. Washington. First, it’s important to recognize that “Low avalanche danger” does not mean “No avalanche danger”. Isolated pockets of instability can be present under a Low rating and you should be capable of recognizing and assessing this hazard for yourself. Second, it underscores the importance of being able to assess hazards before dropping in over the top of them. In this instance, there was at least one skier known to be hiking up Hillman’s with the intention of descending Dodge’s Drop. It’s quite likely that this skier would have triggered the pocket if the climbers had not. Whether the hazard is avalanches, crevasses, undermined snow, etc., it’s always a good idea to assess for hazards before descending from above.
2009-04-11 Looking up to the top of Dodge's there is a crown line in the climber's left side.
http://www.tuckerman.org/photos/tucks/images/2009-04-11%20Fracture%20line.jpg
For the record....