Mt Washington NH Avalanche Bulletin

Forest Service Advisory for Mt Washington, New Hampshire

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Avalanche Advisory for Tuckerman and Huntington Ravines

Posted: 8:50 a.m., Wednesday, January 7, 2009 Tuckerman and Huntington Ravines will have avalanche danger today.

Natural and human triggered avalanches are likely on a variety of slope angles and aspects. Travel in avalanche terrain is not recommended. The only exception to this is the Little Headwall which has avalanche danger. Natural avalanches are unlikely and human triggered avalanches are possible. Use caution.

We are currently under a WINTER STORM WARNING with 10" (25cm) expected by very early Thursday morning. Snow started around 2am this morning on light W winds. Since then winds have marched through the SW and are currently from the S gusting to 41mph (65kph). They will likely move a bit more to the SSE, but will have a predominately S flow until the overnight when they will increase in velocity and move back to the W.

This scenario will directly load N aspects and cross load E facing slopes and gullies today with winds gusting to about 50mph (80kph).

Forecast areas will climb through the ratings eventually getting to the posted "High". Start zones facing the north like areas of Hillman's, Left Gully, South Gully and Odell will reach the High rating first, perhaps early this afternoon as snowfall rates pick up. Areas like Right gully, Yale, Damnation and North gullies will struggle to reach the High forecast and will be the last to do so. These southern aspects are challenging to get to safely due to early season conditions with brush and boulders forcing most people to choose easier approaches.

These easier approaches will put you in the run out paths of northern and eastern facing slopes that will likely have natural avalanche potential much earlier. An example of this is walking up the floor in Tuckerman with the thoughts of getting to Right gully exposing yourself to natural avalanches from the Headwall. So although these S aspects will linger behind other aspects in terms of growing instabilities don't forget the hazards of the approach.

As the inches pile up today temperatures will rise making for heavier slab over lighter densities below it. Sleet at some point is a reasonable bet and there are some crystal balls out there that are predicting worse. Models are much colder than reality making for a very slight chance of rain. Although this possibility is remote it is in the mix of forecast discussions today. If this occurs expect all slopes to jump immediately to High avalanche danger skipping the progressive walk up through 'Moderate' and 'Considerable'. All of these issues developing today are being created on top of the new slabs that have been generated over the past 48 hours with 3.1" (7.5cm) of new snow and high W winds. I would expect natural avalanches to step down and rip out some of these instabilities in some locales. Tomorrow high W winds will keep our avalanche dangers elevated as new slabs will undoubtedly develop as wind velocities rage with more upslope snow. I am crossing my fingers that natural activity is kept to a minimum as we are desperate to keep snow on the slopes and not on the flats due to our recent drought.

The Lion Head Winter Route is open. Mountaineering skills and equipment are required to safely travel on this route. The John Sherburne Ski Trail is open and challenging. Falling snow, flat light and a few inches of new powder will make the ski trail tough for most of the day as it will be difficult to pick out hazards. This will improve a bit by late in the day as snow piles up creating a bit more cushion. Expect new snow to be covering some turf and rocks.

Please Remember: o 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.

o 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.

o For more information, contact the U.S. Forest Service Snow Rangers, 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.

Christopher Joosen, Snow Ranger USDA Forest Service White Mountain National Forest

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