Avalanche Advisory for Tuckerman and Huntington Ravines
Posted: 8:17 a.m., Friday, December 28, 2007

Tuckerman Ravine has High and Considerable avalanche danger today. The Bowl, Lip, Headwall and Left Gully have HIGH avalanche danger. Natural and human triggered avalanches are likely. Travel in avalanche terrain is not recommended. Hillman's Highway, the Lower Snowfields and Right Gully have CONSIDERABLE avalanche danger. Natural avalanches are possible and human triggered avalanches are probable. Be increasingly cautious in steeper terrain. 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.

Huntington Ravine has CONSIDERABLE avalanche danger. Natural avalanches are possible and human triggered avalanches are probable. Unstable slabs are probable in steep terrain. Be increasingly cautious in steeper terrain.

A quick moving weather maker dumped a blanked of new snow on the mountain totaling 5.1" (13 cm) of 10.7% snow at Hermit Lake and 4.5" (11.5 cm) of 11% snow at the Harvard Cabin. The summit recorded 3.7" (9.4 cm) of 13% snow over the past 24 hours. Precipitation began yesterday afternoon around 1:00 pm and initially fell as sleet, rimed snow grains and large needles. Chris observed needles as long as 7 mm. Winds were initially out of the S and SSW and moved to the west around 10:00 last night. Wind speeds steadily increased through the night from the 20 mph range to the current speed of 76 mph (120 kph). The new snow and steadily increasing winds are ideal for creating unstable slab conditions in both Ravines. Looking at wind direction through this event, you can expect that northerly aspects to have been loaded early in the storm. Since the winds have shifted to the west, there has become equal concern about instabilities on east facing aspects which is one reason why areas in Tuckerman Ravine are rated at High. The other factor is these areas provide the largest continuous bed surfaces for the new snow. Expect areas in Huntington to be at the upper end of the Considerable rating due to the possibility of natural avalanche activity. Visibility is limited this morning, but we can tell that Hillman's Highway has already avalanched and ran farther down into it's runout than it has this season. Today's winds are forecasted to diminish through the day which will also decrease the amount of wind transporting that can occur. While this may reduce the amount of snow loading, expect touchy slabs to exist all day.

Another system is on our heels bringing more snow to the mountains tomorrow. The weather models still don't agree on what is going to happen but a blend of all likely scenarios has led to a forecast of 2 to 7" (5 to 18 cm) of snow around northern New Hampshire. Check the weekend update this afternoon for more information on this event. It does look like it will create more stability issues on the mountain so keep your plans flexible this weekend.

The John Sherburne Ski Trail is open with continuous snow from top to bottom. Expect hard icy conditions. THE LION HEAD WINTER ROUTE IS OPEN. This is a steep and challenging route for mountaineers. Crampons, an ice axe and the ability to properly use this equipment are recommended for safe travel on this route.

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 or the AMC at Pinkham Notch Visitor Center or Hermit Lake Shelters or the HMC caretaker at the Harvard Cabin. This advisory will expire at midnight.

Brian Johnston, 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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