This advisory expires at 12:00 midnight, March 25, 2013.
Tuckerman Ravine has CONSIDERABLE and MODERATE avalanche danger today. The Sluice, the Lip, Center Bowl and Chute have Considerable avalanche danger. Natural avalanches are possible and human triggered avalanches are likely. All other forecast areas in Tuckerman Ravine have Moderate avalanche danger. Natural avalanches are unlikely and human triggered avalanches are possible. The Little Headwall has Low avalanche danger. Natural and human triggered avalanches are unlikely in that location.
Huntington Ravine has MODERATE avalanche danger. All forecast areas have Moderate avalanche danger. Natural avalanches are unlikely and human triggered avalanches are possible. Evaluate snow and terrain carefully to identify features of concern.
Brief windows of decent visibility provided Chris and I some snapshots of our current conditions in Tuckerman and Huntington yesterday. The most striking feature was the depth of the avalanche debris that ran across the floor and down towards Connection Cache. The second most striking feature was the areas of slabs remaining above the new crown lines in Sluice, the Lip and Center Bowl. These start zones, plus some others are the targets for our discussion today and the major areas of concern where we feel that the likelihood of human triggered avalanches pushes these areas into the Considerable rating. I don’t expect any natural avalanches to occur since no natural triggers such as new snow, rapid warming or windloading are forecast today. However, the hangfire in the Considerable rated areas as well as in upper start zones on the buttress between Right and Sluice, the upper part of Sluice and the Lip, across the Center Bowl to the now very deep sluff pile in Chute are all pretty ripe for avalanching. The slab in the Sluice is now sitting on the January rain crust which has been the bed surface for two avalanche cycles now, both of which left crown lines 18-36″ deep and 60-100m wide. The two crown lines in Sluice are barely visible due to reloading.
Other areas of concern in Moderate rated gullies are wind loaded areas in the lee of the strong northwesterly winds that we experienced on Saturday. The skier’s right side of both forks in Lobster Claw and the upper skier’s right sides of Right Gully as well as the drop-in on the climbers right of Left Gully are all areas worth evaluating very carefully. The snow was laid in there quite deep making a journey through these gullies a challenging exercise in terrain management and snowpack evaluation for anyone.
Huntington Ravine has many areas of wind deposited snow, some of it soft windslab, to be concerned about. A brief window of visibility this morning and yesterday afternoon revealed some scouring near the tops of Damnation, Yale, and Central but loading in the mid sections and at the gully bottoms. Pinnacle and Odell experienced scouring on the approach and the first pitch of Odell. The middle pitch and top out of Pinnacle is unknown and well worth watching. The middle of Odell and South have pillows of slab deserving of their Moderate rating.
The Little Headwall has some holes in the streambed and some ice to deal with but it is skiable. Though still bushy, the Lower Snowfields can provide some good skiing and riding but don’t ignore the significant threat that looms above in the Duchess and the lower reaches of Deadend Gully. Many folks ski on the treed slope below and between the mouth of Right Gully and Lobster Claw. The trick is to avoid the runouts of all the gullies and to bear in mind that the slope has a steep section of windloaded snow near the base of the cliff as well as some pockets in the middle which can avalanche so use solid travel skills in this terrain. The floor of Tuckerman has filled in substantially from the Center Bowl avalanche. Overall, we are set up well for the coming weeks of spring skiing.
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 8:30 a.m. Monday, March 25, 2013. A new advisory will be issued tomorrow.
Frank Carus, Snow Ranger
USDA Forest Service
White Mountain National Forest
(603) 466-2713 TTY (603) 466-2856