Avalanche Advisory for Saturday, April 15, 2017

This advisory expires at Midnight.

Huntington and Tuckerman Ravine have LOW avalanche danger. Natural and human-triggered avalanches are unlikely. Watch for unstable snow on isolated terrain features. Generally safe avalanche conditions exist.

AVALANCHE PROBLEM: The freeze/thaw cycle taking place, with colder temperatures at night and warmer during the day, is creating a generally stable snowpack. Skier-generated loose-wet avalanches will be the primary avalanche problem today, though with proper management, these can be mitigated safely. South facing slopes that receive the most warming due to prolonged sunlight will hold this hazard the most as well as slopes that see the least amount of traffic through the day. This morning, before slopes soften, long, sliding falls are possible due to a firm snow surface. This hazard will return later in the day when slopes refreeze as they pass into the shade or as they are shaded by cloud cover.

WEATHER: Currently, the Summit is 23F with most of the rest of the mountain hovering around the freezing mark. Through the day, temperatures should rise with the Summit reaching close to 40F by evening.  West wind, currently 36mph, should also gradually increase, with gusts to the 60mph range by the end of the day. The approaching warm front will reach the region by the evening, with clouds starting to move in through the afternoon. It looks like rain showers should hold off until the evening with steady rain and thunderstorms beginning well after dark. 

SPRING HAZARDS: While the avalanche danger today may be Low and the spring skiing will likely be good enough to brag about, there are several springtime objective hazards to be aware of.

  • Icefall and rockfall: As the sun bakes the mountain, the ice floes that linger struggle to cling to the cliffs. While it usually takes a few more warm days than we have seen to really see things start coming down, there is no pattern to the way icefall works. Lunch Rocks in Tuckerman Ravine sits directly beneath some of the biggest chunks of ice in our forecast area. At some point during the season, the ice will cascade from this area. This ice has injured many people and killed at least one. Falling rocks are also possible due to water freezing at night and expanding, followed by melting during the day.
  • Long, sliding falls: Last night, at least one person took a long fall down the Lip, likely due to a refrozen snow surface. Corn snow can turn to cement fast when the shade line moves across the snow surface. Self-arresting is almost impossible on a refrozen surface; plan your last ski run accordingly.
  • Crevasses and undermined snow: Glide cracks are slow to appear so far, however undermined snow and open water holes are prevalent. The waterfall hole is open in The Lip and is growing bigger by the day. The Little Headwall collapsed earlier this week making exiting the Bowl on skis more challenging and possibly more time consuming than walking. Thin spots in the snowpack can be hard to identify, but be aware of them near the edges of snowfields, exposed rock, or where the sound of rushing water can be heard.

The Harvard Cabin is closed for the season. We will continue posting advisories there as long as it is logistically feasible or until the ice melts out and we move to a General Bulletin.

Please 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 caretaker at Hermit Lake Shelters.

Posted  8:00 a.m., Saturday, April 15, 2017. A new advisory will be issued tomorrow.

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