Posted 6:30a.m., Thursday February 24th, 2011
Tuckerman Ravine has MODERATE and LOW avalanche danger. The Lip and Sluice have Moderate avalanche danger. Natural avalanches are unlikely and human triggered avalanches are possible. All other forecast areas have Low avalanche danger. Natural and human triggered avalanches are unlikely. Isolated terrain features may hold pockets of instability in these areas.
Huntington Ravine has LOW avalanche danger. Natural and human triggered avalanches are unlikely except in isolated terrain features.
The beginning of the day should start clear with sunshine prevailing this morning as the high pressure lingers over the mountains. This will slowly transition to increasing clouds with a trace of new snow by the twilight hours. This will wet the chops for the tomorrow’s significant weather maker as a WINTER STORM WARNING has been issued from 7am to 7pm on Friday by the NWS. More about that momentarily, but let’s focus on today for a minute. We continue to have some instabilities hanging on from a snowfall several days ago due to slow consolidation. Cold temperatures and wind have kept many slopes with newly deposited slabs from warming enough to allow enough sintering to drop concerns for all areas. Although the sunshine has allowed solar gain to help a little in a few areas heavily protected from the wind this did not occur on a widespread basis. This was verified yesterday on south facing aspects near the Lobster Claw and Right gully by Justin who witnessed very little heat penetrating into the snowpack. Areas of surface crust remained cool as winds pulled any solar gain off the surface before making much headway. Therefore the Lip and Sluice remain at Moderate avalanche danger today and are the main areas to use all your avalanche skills, knowledge, and experience in as human triggered avalanches are possible. Knowing these areas still harbor some issues locations such as Right Gully retain less instability and risk.
These issues will become fairly moot tomorrow as 10-14” (25-35cm) of snow, with perhaps some sleet, is forecasted to slap the mountains. The system will come from the S to SW during the initial onslaught and shift to the W increasing from an early 25-40mph to 55-65mph in the afternoon. This is an ideal scenario to generate widespread instability on a variety of aspects and enough wind velocity to load copious amounts of snow into the Ravines. If the storm stays on track with the expected moisture, which the models have come into agreement on, I would expect enough avalanche danger to make ravine travel not recommended. Anticipate a High avalanche danger forecast and maybe even the “E” slat (Extreme) depending on intensity rates and timing which we will have a better handle on Friday morning. I would also expect poor to no visibility above treeline during the storm. Currently it appears winds will ramp up Friday night into Saturday causing continued loading into the weekend. Right now I would expect some elevated avalanche danger and some scoured areas Saturday and Sunday. Be sure to read the avalanche advisory each day before heading into avalanche terrain.
- 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.
Christopher Joosen, Snow Ranger
USDA Forest Service, White Mountain National Forest
(603) 466-2713 TTY (603) 466-2856