Posted 8:15a.m., Wednesday, April 13, 2011
Tuckerman Ravine has Moderate and Low avalanche danger today. Left Gully and Hillman’s Highway have Moderate avalanche danger. Natural avalanches are unlikely and human-triggered avalanches are possible. All other forecast areas in Tuckerman Ravine have Low avalanche danger. Natural and human-triggered avalanches are unlikely. Watch for unstable snow on isolated terrain features.
Huntington Ravine is under a GENERAL ADVISORY. You will need to do your own snow stability assessments when using avalanche terrain in Huntington Ravine. A danger of falling ice exists and will persist until it all comes down.
A nasty round of precipitation is on our door step and will bring us snow, sleet, freezing rain and rain today. It is hard to pin down how much snow we will get before the change over but it is looking like 1-3″ (2.5 to 7.6 cm) is a good bet. Winds will be out of the south between 30 and 45 mph (48 and 72 kph). The potential for up to 3″ of snow being blown into north aspects has caused us to bump Hillman’s and Left Gully up to Moderate. This is due to the potential for new slabs to develop and a heightened concern for natural avalanches being triggered in new snow by the change over to rain. If these new slabs do develop, there is a good chance they will be encapsulated by a layer of freezing rain before the transition to rain. We are not overly concerned about significant natural avalanche activity today, but do want you to be aware of this issue. If you choose to endure the yucky weather, it wouldn’t be a bad idea to pick an east or south facing aspect instead of the leeward north aspects. If new snow does accumulate, you should also anticipate wet loose slides to occur when the rain starts pounding on the new snow. Aside from new snow, I think the existing snowpack will be able to absorb today’s rain without increasing the avalanche danger. We have had a series of warm days and rain events and the snowpack has handled it well from a snow stability point of view. That being said, other issues have popped up that you should be aware of. The first is the waterfall hole has opened up in the Center Bowl, near the Lip. This is one of the major drainages in Tuckerman Ravine and it usually rears its head this time of year. It is notable because you really don’t want to fall into this deep waterfall hole and it is difficult to see from above. The other notable change that has occurred recently is the Little Headwall is gone. The increased volume of water in the Cutler River has taken out the snowpack that allows skiers and snowboarders to exit Tuckerman Ravine and get to the Sherburne with ease. The alternatives to skiing out of the Ravine are riddled with undermined snow, open water and bushes.
Keep a close eye and ear out for icefall. Today’s rain may cause some chunks to tumble down to the floor of the Ravine. Crevasses will begin to open up soon. It is important to hike up what you plan on coming down so you can identify hazards. The Sherburne Ski Trail is still open all the way to Pinkham with good coverage. Soft spring moguls can be found on most of the trail with some patches of earth popping up here and there.
- 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
Brian Johnston, Snow Ranger
USDA Forest Service
White Mountain National Forest
(603) 466-2713 TTY (603) 466-2856