Posted 7:50a.m., Wednesday, February 2, 2011
Tuckerman and Huntington Ravines both have HIGH avalanche danger today. Natural avalanches are likely and human-triggered avalanches are very likely. Travel in avalanche terrain is not recommended. The only exception to this rating is the Little Headwall, which has Moderate avalanche danger along with open water and thin cover. Natural avalanches are unlikely in this area but human-triggered avalanches will be possible as the day develops.
It’s been 2 weeks since the mountain received snowfall greater than 2” (5cm) over the course of a day. Today we will break that trend. Snow has already begun to fall and the wind has made the swing from W to SE. Wind speeds are currently around 30mph (48kph) and expected to soon push to 45mph (72kph) with higher gusts. Snow accumulation is forecasted to be around a foot (30cm) by this evening and cold temperatures will hopefully keep it light and fluffy. This lighter density snow is a perfect match for the forecasted winds and I would expect lots of loading without the scouring that we typically see at higher wind speeds. The areas that will benefit most from wind transport are fortunately enough, the areas that need it most. North facing aspects such as the Escape Hatch are ill with wanting as past storm events have done little to fill them in. We expect that they will slide first in a series of avalanche cycles the mountain will see today. Areas with NE and E aspects such as Hillman’s Highway, Left, South and O’Dell gullies will see significant cross-loading today and natural avalanches are likely to occur. These paths are fairly well developed especially as you move toward a true E aspect. As a result avalanches should push farther than they have so far this season filling in the talus and covering the vegetation in the ravine floors. If you’ve gone in “just to take a look” you may be putting yourself at risk of burial as well. Avalanche terrain includes the run-outs of slide paths. South facing aspects will receive the least amount of wind-loading today but we expect to see avalanches result in these areas from the increased load of the new snow. Prior to this storm SE aspects contained the snowpack instabilities that concerned us most. These are now getting buried and further stressed by the weight of new snow.
This storm is expected to pull away tonight and cause winds to wrap to the NW. The current models are showing wind speeds that are slow to rise as the system pulls out but I wouldn’t be surprised if tomorrow’s weather forecast for the higher summits calls for something higher than the 35mph (56kph) that is now forecasted. Nonetheless, shifting wind to the NW and the possibility of a couple more inches of upslope snow makes me think we’ll still have elevated avalanche danger tomorrow. It is possible we will have some lingering instabilities into the weekend from this storm event and the subsequent upslope conditions that will follow. This will be compounded by another precipitation storm event that looks to be developing for Saturday and Sunday. Make sure you check back in tomorrow morning to get the latest.
- 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.
Justin Preisendorfer, Snow Ranger
USDA Forest Service
White Mountain National Forest
(603) 466-2713 TTY (603) 466-2856