| Posted: 8:52 a.m., Thursday, February 14, 2008 |
Huntington Ravine has Considerable avalanche danger. Natural avalanches are possible and human triggered avalanches are probable. Be increasingly cautious in avalanche terrain.
Yet again we have had another round of interesting weather and avalanche activity. The summit recorded 6.7" (17cm) of snow yesterday. Temperatures on top failed to exceed 30F (-1C), so precipitation type up there remained as snow all day. Farther down the mountain it's a different story. Temperatures yesterday afternoon in the ravines were in the mid to upper 30'sF, allowing the falling snow to melt into freezing rain. The crust we're observing in the base of Huntington and around Hermit Lake is fairly thick and has a slick glossy upper surface. Around the mountain, including in the upper reaches of the ravines, drainage channels are visible on the snow surface which tells us this crust is present in the avalanche start zones as well as at lower elevations. In our morning discussion, we speculated about how much this crust would encapsulate the snow that fell before it got warm. The answer is apparent to anyone looking up at ravines and seeing the plumes of snow blowing around this morning. You can actually see the crust being ripped up by the wind; the underlying snow is then being blown into the ravines on NW winds that are at the upper end of their forecasted speeds for the day. The wind is depositing the snow into many of our normal avalanche paths, but most prevalent are those with SE and E aspects such as Central Gully in Huntington and the Lip and Headwall areas in Tuckerman. However, these are not the only locations receiving new loading. Cross loading is taking place in many other areas of both ravines. I expect the newly developing slabs to be sensitive and reactive. It shouldn't take a lot of effort to get one of these slabs to release, and it's possible this will happen naturally from additional snow loading even though it's a bluebird day. Today's winds are expected to slow down slightly from their current speeds, however as long as the crust is able to be eaten away the underlying snow will be available for transport. If the snow loading ceases entirely, the possibility of natural avalanches will also decline, but the remaining slabs will still be sensitive to human triggers, keeping the avalanche danger at Considerable. The concern in Tuckerman's Lower Snowfields is related to avalanches spilling out of the Duchess and Dead End gully. The snowfields themselves are essentially a debris pile right now. If you are in this area, pay close attention to what is taking place on the ridgeline above you.
Yesterday's weather did produce a number of avalanches. Many of these were loose wet slides, while others were slabs. We're now becoming accustomed to seeing avalanche activity in atypical locations. Fractures this morning were evident in a couple of faint gullies farther down the ridge from the Escape Hatch. The Boott Spur ridge has multiple slides from Gully #2 all the way over to the Dead End gully. Left Gully has a fracture line down in the constriction below the funnel. Lately we've been talking a lot about unusual activity. Keep this in mind as you are planning your trip up here, whether it's for today, this weekend, or next month. What we've come to think of over the past couple years as "safe places" is not necessarily the case anymore.
As always, crampons, an ice axe, and solid self arrest skills are recommended for travel in steep terrain. This includes the Lion Head Winter Route. The Sherburne Ski Trail is open with a nasty breakable crust.
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Avalanche Advisory Archives.
United States Avalanche Danger Descriptions.
Échelle Canadienne de risque d’avalanche.
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