Posted at 8:15, Tuesday, February 22, 2011
Tuckerman Ravine has MODERATE and LOW avalanche danger. The Chute, Center Bowl, Lip, Sluice and Right Gully have Moderate avalanche danger. Natural avalanches are unlikely and human triggered avalanches are possible. Hillman’s Highway, Left Gully, Lobster Claw, Lower Snowfields and the Little Headwall 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.
Canadian high pressure settled into the region last night and this morning we’re treated to bluebird skies and excellent visibility. Yesterday’s winds stayed fairly constant at 45-65mph (72-107kph) as they made the shift from the WNW to the NNW. The observers at the summit recorded blowing snow during every hourly observation until just after midnight when the winds made the move to the N and decreased slightly in speed. Fueling this wind transport was 0.8″ (2cm) of snow that fell early yesterday morning and then light snow showers that persisted through much of yesterday but left little more than a trace. Despite the lean amount available for transport, areas in the direct lee of the wrapping winds developed new windslab in protected locations. These new slabs are thin in most areas but still noteworthy. In the Lip wind-deposited snow has completely obscured the crown line that was visible Sunday afternoon. Other fracture lines from the last avalanche cycle are still visible such as the one in the Chute and another on the climber’s right side of the Center Bowl. Diminished concerns for natural activity have allowed some areas to drop a rating from where they were yesterday but a range of conditions still exists within each hazard rating. I would consider the Chute and Right Gully to be on the lower end of the Moderate rating while the Lip and the Sluice are on the upper end. The Sluice looks exceptionally smooth compared to other areas and its slopes provide some of the best protection for NNW winds. In my opinion it is the area of most concern today but also the one with the most allure. Don’t get sucked in!
The temperatures yesterday were downright frigid and we saw lots of chilly visitors trying to make the most of the holiday. After a drop to -17F (-27C) at the summit last night we’ll see some rebound today with highs in the upper single digits (F). Tomorrow will get even a little warmer but for now it’s still puffy jacket time. The snowpack is rooting for warmer weather as well because temperatures like these are not conducive to the sintering of snow crystals and the formation of bonds that are necessary for stabilization. Until the mercury pushes a little higher the instabilities and associated potential energy in the snowpack will persist and buried crust layers will continue to inhibit vapor transport and the move toward an isothermic state. I’m not lobbying for a spring corn cycle quite yet but a day slightly above freezing would be really nice!
- 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