Avalanche Advisory for Saturday, March 3, 2018

Huntington Ravine has MODERATE avalanche danger. All forecast areas have Moderate avalanche danger. Evaluate snow and terrain carefully.

Tuckerman Ravine has MODERATE and LOW avalanche danger. Lobster Claw and Right Gully have Moderate avalanche danger. Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully. Sluice, Lip, Center Bowl, Left, Hillman’s Highway and Lower Snowfields have Low avalanche danger. Watch for unstable snow on isolated terrain features. The Little Headwall is an open stream and is not rated.

AVALANCHE PROBLEM: Areas of new wind slab are the primary avalanche problem though the primary hazard remains the potential for taking a high-speed sliding fall from steep terrain on the frozen, icy snowpack. Brief windows of visibility into Tuckerman Ravine have confirmed suspicions that much of yesterday’s new snow was scoured off of windward facing forecast zones by high winds from the east-northeast. The high wind speed and easterly direction coupled with very limited fetch, or area of available snow for transport, leads us to our low rating in most areas. Forecast areas that face due east contain much more limited areas of wind slab. These areas should be assessed carefully for sensitivity to human-triggering and consequences of being swept off your feet. More sheltered areas like the long northern gullies in Huntington and Lobster Claw and Right Gully in Tucks will likely harbor larger and harder to avoid wind slab. Human triggered wind slabs are possible where they have developed in steep terrain. Up to an inch of new snow today on continued NE wind will add slightly to existing wind slab.

WEATHER: Wind from the northeast continues to blow this morning in the mid-50s mph and will remain from that direction through the day. Though temperatures will be on the mild side for this time of year, mid teen’s F will keep things feeling wintry. Yesterday’s highly elevation dependent snowfall brought 6.1” of snow to the summit and 2.4” of 20% density snow to Hermit Lake. Winds remained in the 60s and 70s mph during the storm which would have been an ideal loading speed had they blown from the west. Winds will continue to move some snow today as they blow in the 50 mph range from the northeast. Count on limited visibility through the day due to persistent summit fog, up to an inch of new snow, and a challenging headwind above treeline on a return trip on the Lion Head route.

SNOWPACK: An unusually warm February started to create hazards more typical of spring. Glide cracks, waterfall holes and ice that has gone through dramatic temperature swings are all in play now. The old, gray surface was saturated during earlier rain events and has now refrozen into a barely edge-able and slick surface. Three people have taken long sliding falls on this surface in the past week and though they were lucky to only receive minor injuries, history has shown the consequences of falls like this can lead to serious injuries and even death. Be sure to develop alternate plans if you or your group is strongly driven to get into steep terrain today, the consequences of pushing it are often much more severe than anticipated.

The John Sherburne Ski Trail was freshened up by a few inches of dense snow yesterday but still holds a wide variety of conditions, including exposed rocks, areas of water ice. Plenty of skiable snow remains but cautious and careful turns are advised.

The Harvard Cabin will be open Saturday night.  

Remember:
• 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 8:00 a.m., Saturday, March 3, 2018. A new advisory will be issued tomorrow.

Frank Carus, Lead Snow Ranger
USDA Forest Service
White Mountain National Forest
(603) 466-2713 TTY (603) 466-2856

2018-03-03