Posted 8:30am, Saturday, March 5, 2011
Tuckerman Ravine has Moderate avalanche danger. Natural avalanches are unlikely and human triggered avalanches are possible. The only exception to this rating is the Little Headwall which has Low avalanche danger. Natural and human triggered avalanches are unlikely.
Huntington Ravine has Moderate and Low avalanche danger. Central, Pinnacle, Odell, and South Gullies will have Moderate avalanche danger. Natural avalanches are unlikely and human triggered avalanches are possible. All other forecast areas have Low avalanche danger. Natural and human triggered avalanches are unlikely.
Brace yourselves, we’re about to go on a wild ride over the next 48-72 hours. The bulk of incoming precipitation isn’t expected until Sunday. Currently at Hermit Lake, snow has begun to fall and will continue with light accumulations throughout today. Anywhere from a mere trace to upwards of 2″ (5cm) is expected to fall; during this time winds will be from the SW and increasing to a gusty 60-80mph (97-129kph). Weather forecasts begin to diverge as to the timing of the precipitation changing over to a mix of sleet and snow. The meteorologists do agree that it will change over as temperatures begin to rise, however, the big questions are when will this happen and how much slab was able to build in the meantime? These are important factors that should grab your attention today. The expected snowfall amounts along with wind speeds and direction will be able to load new snow creating slabs in many areas, particularly those with a N, NE, or E aspect. We believe the trace to 2″ snow forecast will keep the amount of slab development small enough that human triggered avalanches would be the primary concern, rather than naturally triggered avalanches. This is the reason why some areas that were posted at Low yesterday are rated Moderate today, namely Hillman’s and Left Gully in Tuckerman and Central, Pinnacle, Odell, and South Gullies in Huntington. These areas were starting today without much avalanche concern, but as the day progresses and slabs are able to build, then they will push into the Moderate rating. Similarly, some of those areas that were posted at Moderate yesterday will be on the receiving end of windblown snow. Some of these could push into the upper end of the Moderate rating by the end of the day. These areas include the Chute, Center Bowl, Lip, and Sluice.
Like every other day, we are basing today’s ratings on expectations of future weather, and it is your responsibility to pay attention to the actual weather. Today this deserves special attention, as seemingly small differences between forecasted weather and actual weather can make a significant difference in the avalanche hazard today. Factors that can cause the avalanche danger to rise above the current ratings include:
- Greater than expected snow accumulations
- Earlier than expected change over to mixed precipitation
- Rain at any time on the current snowpack or falling on slabs developed today
- 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.
- This advisory expires at midnight. 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