This advisory expires at Midnight 3-21-2013
Tuckerman Ravine has CONSIDERABLE and MODERATE avalanche danger. The Lip, Center Bowl, Chute, and Left Gully have Considerable avalanche danger. Natural avalanches are possible and human triggered avalanches are likely. The Lobsterclaw, Right Gully, the Sluice, Hillmans Highway, The Lower Snowfields, and the Little Headwall have Moderate avalanche danger. Natural avalanches are unlikely and human triggered avalanches are possible.
Huntington Ravine has CONSIDERABLE and MODERATE avalanche danger. Central, Pinnacle, Odell, and South gully have Considerable avalanche danger. Natural avalanches are possible and human triggered avalanches are likely. North, Damnation, Yale and the Escape Hatch have Moderate avalanche danger. Natural avalanches are unlikely and human triggered avalanches are possible.
Another 8″ (20cm) on Wednesday was recorded on the summit totaling 24″ (60cm) for the storm and 40″ (102cm) for the week! Ideal loading from moderate and high NW and W winds have given both Ravines BIG gains in the last 2 days. Although some clouds are hiding all the ravine secrets a number of gullies and slopes have both avalanched and grown substantially. In Huntington, natural avalanche evidence can be traced to Damnation, Yale, Odell, and South gullies. I would suspect Central avalanched as well but it is not evident. In Tuckerman avalanche debris can be seen under Dodges Drop which ran into Hillman’s, Hillman’s Highway, the Duchess, and the Sluice. The Sluice ran big. A deep fracture line remains across the steepest part of the Sluice, to the climbers left of the water ice. It rips down to the Open Book area near Lunch Rocks, and appears to head up into the Knife Edge towards Right Gully. Joe and I look forward to seeing what she left in her wake on the floor of Tuckerman later this morning. Currently no fracture lines are visible in the Tuckerman Center Bowl which tells me an avalanche cycle occurred early in the storm and has reloaded.
Early this morning light snow fell on a dropping NW wind, currently blowing at +/- 35mph. This falling velocity trend is expected to continue which will limit new loading for most of daylight hours. Tonight this will all change again with increased winds and more light upslope snow. Generally, what we’re dealing with today is the concern of human triggered avalanches being between “possible” and “likely”. Areas posted at Considerable have grown substantially and are mostly devoid of any wind effect evidence-i.e. smooth, they are also recently loaded from an overnight WNW wind. Some of these rated areas have become much larger such as Odell and Central in Huntington and The Lip in Tuckerman. You will likely find multiple layers, some quite thick, with varying weaknesses from this storm. This is due to wind speeds ramping up and down, as well as a plethora of crystal types from large stellars to heavily rimed graupel. All other forecasted areas are either a solid Moderate or are sitting on the upper end of the rating. You can expect more obvious spatial variability in the Moderate forecasted area than those posted at Considerable. Anticipate wind effect sastrugi, a little old hard surface, and areas of unstable new slab. This diversity is well demonstrated in Lobster Claw and Right Gully. In Huntington’s Yale and Damnation wind effect is less obvious, but the size of instabilities are smaller due to their tighter ribbon like nature compared to slopes found in Central and Odell.
It is a heads up day with all forecast areas teetering between Moderate and Considerable right after a storm. This is exactly the conditions that get people in trouble worldwide causing avalanche accidents. The vast majority of backcountry users stay away from avalanche terrain during very obvious “High” avalanche danger in the midst of the storm. However, as instability decreases and the blue skies erupt, powder hunger tempts gluttons to get after it. This is a dangerous scenario. There can be reasonable options for a skilled user with good avalanche knowledge, but a honest, objective assessment is critical to overcome your bias to jump into the steep and deep. Cautious route finding and conservative decision making is essential to come back and play again in the mountains.
- 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 8:55 a.m. Thursday 3-21-2013. A new advisory will be issued tomorrow.
Christopher Joosen, Snow Ranger
USDA Forest Service
White Mountain National Forest
(603) 466-2713 TTY (603) 466-2856