Expires 12:00 midnight, Saturday, January 07, 2012
Tuckerman Ravine has Moderate and Low avalanche danger today. The Sluice, Lip, Center Bowl, and Chute have Moderate avalanche danger. Natural avalanches are unlikely and human triggered avalanches are possible. Heightened avalanche conditions exist on specific terrain features; evaluate snow and terrain carefully and identify features of concern. Left Gully and Hillman’s Highway have Low avalanche danger. Natural and human triggered avalanches are unlikely. Watch for unstable snow on isolated terrain features. Some areas are not yet posted due to the overall lack of snow. These include Lobster Claw, Right Gully, the Lower Snowfields, and the Little Headwall in Tuckerman. Forecasts for these locations will begin when conditions warrant.
Huntington Ravine has Moderate and Low avalanche danger today. Yale, Central, Pinnacle, and Odell have Moderate avalanche danger. Natural avalanches are unlikely and human triggered avalanches are possible. North, Damnation, and South gullies have Low avalanche danger. Natural and human triggered avalanches are unlikely. The Escape Hatch is not posted.
Although down in the valley it certainly seems like winter snow will never arrive, Mt. Washington has recently been a different story. There has been measurable snow on the summit every day so far this year (7.6”/19cm in January) and winds have been doing an excellent job of moving the available snow into the ravines. This has put us firmly into avalanche-worthy conditions over the course of the past week. Two avalanche incidents took place this week in Huntington Ravine, and this morning evidence of natural avalanche activity can be seen in Left Gully and Dodge’s Drop. The crown lines from these are large enough to make me glad to not have been near them when they released.
Today the primary concern for people heading into the ravines will be human triggered avalanches on the existing slabs. These have been created over the last few days on strong winds from a mostly westerly direction. We have a widely variable snowpack overall. Areas that are often entirely covered with snow are currently broken up by rocks, ice cliffs, sub-ridges, etc. This is creating a situation where it is difficult to take information you collect in one location and extrapolate it to another. You’ll need to stay vigilant for changing conditions as you move from one patch of snow to another. For example, in the Center Bowl and Chute areas of Tuckerman you can find some areas where wind effect is prominent and other areas have softly loaded pillows of windslab. The Lip has filled in a lot lately, and although the whole area is still broken up by bands of rock and ice, the strong leeward aspect of this area has allowed snow to load onto the growing bed surfaces here. I would expect these snowfields to be some of the most reactive to human triggers. Remember that a lot of this recent snow is sitting in numerous crust layers from past weather events.
Areas posted at Low danger are not without hazard. Isolated pockets exist in many of these locations that may have instability issues. The top of Left Gully is one example, similar conditions exist in Huntington’s Low areas. In Huntington, the areas of greatest concern are the deposition areas at the top of the approaches, just before the ice climbing begins. Central, Pinnacle, and Odell all have areas of wind-loaded snow below them. Yale warrants a Moderate rating for a similar reason, but it is on the lower end of the spectrum.
- 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 8:50a.m. January 7, 2012. A new advisory will be issued tomorrow.
Jeff Lane, Snow Ranger
USDA Forest Service
White Mountain National Forest
(603) 466-2713 TTY (603) 466-2856