Posted 8:20a.m., Saturday, February 19th, 2011
Tuckerman Ravine and Huntington Ravine 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 in Tuckerman Ravine which has Low avalanche danger. Natural and human triggered avalanches are unlikely. Watch for unstable snow on isolated terrain features in this area.
Today’s weather is not what we were expecting twelve hours ago and avalanche conditions are a significant issue. Yesterday we were expecting winds to reach 100 mph (160 kph) and an inch or two of snow. Now the higher summits forecast is calling for NW winds between 50 and 70 mph (80 to 113 kph) with higher gusts. Snowfall has proven to be higher than expected, providing the key ingredient for today’s avalanche danger. The Hermit Lake snow plot picked up 4.5″ (11.5 cm) of snow with a density of 6.5%. The Harvard Cabin snow plot received 4.9″ (12.5 cm) of 5% snow while the Summit only recorded 1.5″ (3.8 cm) so far. Our field observations this morning are finding a consistent blanket of about 7″ (17 cm) of new snow in the base of Huntington Ravine and along the Tuckerman Ravine Trail below Hermit Lake. Some additional light accumulation can be expected to add to these amounts today. The stability issues today are pretty simple. The new snow will be blown into the Ravines by ideal winds out NW resulting in an unstable snowpack in most forecast areas. We expect that many paths will produce natural avalanches making it a bad day to head into the Ravines, even to have a look around.
If you plan on heading above treeline you can leave the Bermuda shorts behind. Winter has returned and today’s temperatures are forecasted to be around 0F (-18 C) on the summits. Even though winds speeds aren’t going to be as high as they were originally forecasted to be, 50 to 70 mph winds are challenging for us bipeds and the new snow will allow for whiteout conditions. The recent warm weather has left an unconsolidated snowpack in the woods that hasn’t had an opportunity to freeze up yet. If you plan on going off trail, bring snow shoes or skis.
- 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