Avalanche Advisory for Saturday, February 24, 2018

Huntington Ravine and Tuckerman Ravines have LOW avalanche danger. All forecast areas have Low avalanche danger. Generally safe avalanche conditions. Watch for unstable snow on specific terrain features. The Little Headwall is an open stream and is not a viable route out of Tuckerman Ravine.

AVALANCHE PROBLEM: Small and isolated pockets of new wind slab may exist in our terrain. Minimal new snow overnight has been heavily affected by westerly wind. Most of our terrain remains a hard, refrozen snow surface where avalanches will not be your primary concern. This icy and particularly slippery snow will require appropriate traction devices in any terrain. This means crampons and ice axes on snow slopes and steep trails and microspikes elsewhere. Consequences of a sliding fall on our hard, icy snow remain high, with numerous rocks and other hazards exposed below steep terrain. Appropriate terrain choices and travel skills will help you avoid a high speed fall that could result in serious injury or worse.

 WEATHER: Yesterday brought 0.30 inches of water to the summit which fell mostly as rain, freezing rain, and sleet. Only 0.5 inches of snow was recorded. The little snow we received fell on SW wind that shifted W and ramped up overnight to the current gusts over 100 mph. Temperatures hovered just above freezing at Hermit Lake and just below freezing on the summit late yesterday and last night. It has now turned colder, with a steady summit temperature around 20F forecast today and likely a few degrees warmer in our terrain. Wind and summit fog should decrease through the day. A system moving in late tonight will bring snow and possibly mixed precipitation tomorrow as summit temperatures approach the high 20’s F. This storm which is forecast to become increasingly warm could bring over 6” of new snow, though timing of the forecast changeover to mixed precipitation will ultimately determine new snow accumulation.

SNOWPACK: The mixed bag of precipitation late yesterday and overnight largely fell as rain, freezing rain, and sleet, all of which refroze and now contribute to our hard and icy snow surface. The limited new snow mixed in this storm was heavily transported by wind, and at best amounted to quite small wind slabs that pose little danger to travelers in the alpine. Potential for a long sliding fall on our largely hard and slick snow surface should guide your terrain choices today. Realize that preventing such a fall is essential, as arresting one would be very difficult. Crampons, ice axes, and your ability to use them are essential on snow slopes. Clear skies and sun may briefly and slightly soften snow on south-facing aspects this afternoon, but this window of anything but rock-hard snow will be brief if it happens at all.

 The John Sherburne Ski Trail holds icy snow with patches of water ice and bare ground.

• 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 Harvard Cabin.
• Posted 7:45 a.m., Saturday, February 24, 2018. A new advisory will be issued tomorrow.

Ryan Matz, Snow Ranger
USDA Forest Service
White Mountain National Forest
(603) 466-2713 TTY (603) 466-2856