Avalanche Advisory for Tuckerman and Huntington Ravines
Posted: 7:35 a.m., Sunday, March 18, 2007

Tuckerman Ravine currently has LOW and MODERATE avalanche danger. The Lower Snowfields and Little Headwall have 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 have Moderate avalanche danger. Natural avalanches are unlikely and human triggered avalanches are possible. Use caution 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.

The weather of the past 24 hours has left us scratching our heads a bit. Unfortunately we didn't see anywhere close to the 15-20" that had been forecasted nor did we stay with the preferred precip type of snow. Warm air aloft created a pronounced inversion and the Summit spent a good chunk of the day at higher temps than down at Pinkham Notch. All elevations saw freezing rain and ice pellets while only the upper elevations seem to have seen any actual rain. The result has been a wide variety of crust styles as you move around the mountain. Near the base of the Ravines the makeup seems to be mostly in the form of a thin ice lens that overlies a 1-2cm porous crust. At the Summit the upper layer of the snowpack can hardly be called a crust as warmer temperatures allowed water to penetrate deeper into the snowpack before freezing. The result is a thick layer of very hard snow that is similar to typical spring conditions when the sun has yet to turn the bulletproof surface into nice corn snow. The stout nature of this "crust" layer will likely prevent today's increasing winds from accessing the lighter and drier snow that is encapsulated below. WNW winds are expected to gain strength throughout the day before reaching 85+mph(137+kph) toward dusk. Whatever snow isn't shielded by the crust will be available for transport. This includes close to 1"(2.5cm) that the Summit has picked up since midnight as well as another inch or so that will be deposited by today's upslope energy. Keep a close eye on accumulating snow if you venture into avalanche terrain today. Any new windslab that develops will be of the cold, light density variety and will be resting on a very slick surface. These types of conditions often allow for even small isolated pockets of windslab that are reactive to human triggers. With this in mind you should keep your guard up even in areas that are rated Low today. Some of the areas have not yet reached their posted rating as of this morning but the danger will rise as more snow falls and wind speeds increase.

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 a fresh covering of crusty snow to hide the bare spots and rocks that melted out last week. Keep those tips out from under the junk!

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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