Avalanche Advisory for Tuckerman and Huntington Ravines
Posted: 7:08 a.m., Wednesday, March 14, 2007

Tuckerman Ravine has LOW and CONSIDERABLE avalanche danger. The Little Headwall has Low avalanche danger. Natural avalanches are very unlikely and human triggered avalanches are unlikely except in isolated pockets. Normal caution is advised. All other forecast areas in Tuckerman Ravine have Considerable avalanche danger. Natural avalanches are possible and human triggered avalanches are probable. Be increasingly cautious in steeper terrain.

Huntington Ravine has LOW avalanche danger. Natural avalanches are very unlikely and human triggered avalanches are unlikely except in isolated pockets. Normal caution is advised.

Summit temperatures climbed above freezing yesterday once the sun went down. Light rain fell on all areas of the mountain with Hermit Lake's rainguage measuring .1"(2.6mm) and the Summit recording .1"(2mm). More rain is expected today with light showers this morning followed by heavier rain this afternoon. Up to .25"(.64cm) of rain is expected today with more in store for tonight and tomorrow. When constructing a forecast this morning it has helped to use the following equation: Recent rain + incoming rain + meltwater=total amount of free water in the snowpack. With the Summit currently registering 38F(3C) and Hermit Lake pushing 50F(10C) we can expect to see a fair amount of water freed up by melting of the snowpack's upper layers. All of this free water is trying to percolate down through the various layers of the snowpack on its way toward the ground. In Tucks it travels through a snowpack that is very stratified with multiple layers of facets and a couple of pronounced crusts. When it intersects the less permeable crust, free water will usually begin flowing downhill on top of the crust especially if the overlying layer is composed of faceted snow. This action lubricates the interface and deteriorates bonds between snow grains. With the additional weight of rain added to the mix, the snowpack balances dangerously between stress and strength. After a certain point the stress may outweigh the strength and failure of the slab layers will initiate an avalanche. So why one ravine at Low while the other is at Considerable? The reason for this can be found in the different snowpacks. Huntington Ravine has a much less stratified snowpack and does not have the same sensitivities in its upper layers as Tuckerman. The main concerns in Huntington are focused on falling rock/ice, detached ice, and the failure of pockets of snow that are sitting on water ice. As you might have guessed we are more concerned with natural activity today than we are with human-triggered avalanches. Most areas will start the morning with a rating of Low but will be climbing in the danger rating scale as we see more melt and heavier rain. Any avalanche activity that occurs today may be very impressive in its size and mass. Keep an eye on the sky if you're out there recreating today. If rainfall exceeds the forecasted amounts or we see periods of high intensity rainfall you should expect the avalanche danger to rise. Be your own forecaster!

The Lion Head Winter Route is open. This is a steep and challenging route. Crampons, an ice axe, and the ability to properly use this equipment are necessary for safe travel on this route. The John Sherburne Ski Trail is open with top to bottom coverage, but expect bare spots to be opening up with this period of melt.

Please Remember:
•   It is impossible to accurately predict natural events, such as avalanches, in every instance. This Advisory is one tool to help you make your own decisions in avalanche terrain. It should be used along with safe travel techniques, snow stability assessments, an understanding of weather's effect on the snowpack, and proficiency in avalanche rescue.
 
•   You should obtain the latest weather forecast before heading into the mountains. Anticipate a changing avalanche danger when actual weather differs from the National Weather Service forecast.
 
•   For more information, contact the U.S. Forest Service Snow Rangers, the HMC Caretaker at the Harvard Cabin, and the AMC at Pinkham Notch Visitor Center or Hermit Lake Shelters. This advisory will expire at midnight.

Justin Preisendorfer, Snow Ranger
USDA Forest Service
White Mountain National Forest
(603) 466-2713 TTY (603) 466-2856
 
This is the Official Tuckerman Ravine website.  Occasionally the remoteness of Tuckerman Ravine, weather, or communication problems prevent the website from being updated immediately.  Check the date, and if it is not the most recent, you can also call the National Forest Service's 24 hour avalanche hotline at (603) 466-2713 (ext. 4)

Avalanche Advisory Archives.

United States Avalanche Danger Descriptions.

Échelle Canadienne de risque d’avalanche.

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