Expires 12:00 midnight, 1-31-2012
All forecasted areas of Tuckerman Ravine have Considerable avalanche danger. Natural avalanches are possible and human triggered avalanches are likely. The Lobster Claw, the Lower Snowfields, and the Little Headwall are not posted due to an overall lack of snow. Forecasts for these locations will begin when warranted.
Huntington Ravine has Considerable and Moderate avalanche danger. Central, Pinnacle, Odell, South, and the Escape Hatch have Considerable avalanche danger. Natural avalanches are possible and human triggered avalanches are likely. North, Damnation, and Yale Gullies have Moderate avalanche danger. Natural avalanches are unlikely and human triggered avalanches are possible.
It’s the last day of January and I can’t make up my mind whether to celebrate January or curse it. Compared to December 2011, it was a great month for snow. But on the other hand, far too many days went well above freezing, the most recent being just last Friday, the 27th. Looking at the current weather, the month will end with some accumulating snow. February will open on a sour note, with the weather turning warm once more. It’s currently looking like rain may once again land in avalanche terrain tomorrow. But for now, we’ve just started to receive snowfall that will add to the stability issues that have been keeping us on our toes for the last few days. About an inch of new snow is on the ground and we’re expecting another 3-4” (7.5-10cm) before the day is over. This snow will come with winds on the lighter side for up here. They will be from the west in the 30-45mph (48-72kph) range, which is an excellent speed for allowing loading to take place in the upper elevations of avalanche terrain. As warm air slowly takes over, snow densities will be increasing. Additionally, winds are forecasted to increase in speeds slightly during the day and into the overnight. Together these two factors will make for an upside-down effect in the new slabs. This means we’ll have lighter, weaker snow buried beneath heavier, denser snow. It’s a classic recipe for avalanche activity, so today’s a good day to play it very conservatively with your travel plans.
Yesterday afternoon the skies cleared briefly enough for us to get a good look into both ravines. The loading that occurred in Tuckerman was impressive. Our estimate is that 2-3 feet of deposition took place in strong lee areas such as the Lip and Center Bowl. Not only is new snow problematic here, but the underlying layers have numerous potential weaknesses within the complexity of layering. The exposed crust that dominates Left Gully may have some trouble holding new snow, but in the strong lee of the upper gully there is a likelihood for slabs to develop under today’s conditions. In many locations, anchors have been slowly getting buried, making their effects less important to overall stability. The upper sections of Sluice and Right Gully are good examples. In Huntington, the areas we rated Moderate today have much less developed bed surfaces than all other gullies. It is still possible that you might find unstable areas of snow in North, Damnation, and Yale. The snowfields in the other gullies have all grown in size in recent days and will have the largest potential sliding surfaces for avalanches caused by the new snow.
Above all else, keep in mind that the avalanche danger is increasing as the day goes on. In many areas we’re starting the day with a Considerable rating, and now additional loading is taking place. Don’t let the powder fever allow you to let your guard down.
- 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 8:15am. 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