Avalanche Advisory for Friday, March, 30, 2018

Huntington and Tuckerman Ravines have MODERATE avalanche danger. All forecast areas have Moderate avalanche danger. Heightened avalanche conditions on specific terrain features.

AVALANCHE PROBLEM: Rain on cold, dry layers of snow raises our avalanche danger today. Warm temperatures and rain overnight will continue into the early afternoon hours today, adding strain to the weak layers that exist in the snowpack. There is a good chance that no natural avalanches will occur today, but any avalanche, natural or human-triggered, could be large and destructive. If, for some reason, you venture out into avalanche terrain in the cold rain today, keep this low probability but high consequence avalanche problem in mind. Temperatures will fall to the freezing level this afternoon and continue to drop through the night bringing improved stability to the snowpack. It will also create a hard, icy surface layer that sunshine and cool temperatures tomorrow may have a hard time breaking down.

Spring hazards are becoming prominent and should be considered in your terrain decisions. Long sliding falls on the hard, icy snow will be possible. Given the rain and refreeze, don’t count on the firm Styrofoam snow to be around tomorrow. Ice climbers should be aware of potential for ice dams in many climbs which can rupture with the placement of a tool, crampon, or screw. Above freezing temperatures will result in water flowing beneath ice which will become brittle in places when temperatures drop tonight. Undermined snow in stream beds will make exiting the Bowl challenging.

WEATHER: About a 0.4” (9.7mm) of rain fell overnight at Hermit Lake with more on the way today. The temperature is currently 39F on the summit and will slowly fall through the day, ultimately bottoming out at 8F on the summit at sunup tomorrow. West wind today will diminish a bit to 40-45 mph this afternoon but slowly ramp up and blow 65-70 mph tomorrow morning. Summit wind will diminish a bit tomorrow afternoon to 55-60 mph. Sunny skies are on tap and will likely seem appealing for a spring ski day but be prepared for borderline snow conditions which may struggle to soften even on sunny aspects.

SNOWPACK: Field time on the summit yesterday was a reminder of how important the direct sun and above freezing temperatures are to soften the snow surface. The more east facing snowfields were rock hard at 12 noon, despite sunlight filtered only by very thin, high clouds and temperatures at 34F. Wind from the west near 40 mph and indirect sunshine were enough to keep the snow from softening. Lower down the mountain, conditions improved on slopes facing directly into the sun but temperatures were quite warm there early on. Solar gain will be critical tomorrow. If you are choosing to come up on Saturday, remind yourself that the pressure that comes from a crowd of people is hard to withstand. Long-sliding falls often result in no injury whatsoever but have, on many occasions, resulted in life altering injuries and death. Look for sun softened snow, not the boot ladder with the most people.

Check our Instagram page, linked on our website, for conditions photos and additional updates. You don’t need an account to view our posts!

The Harvard Cabin will be open tonight and Saturday night and then close for the season.

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 caretakers at Hermit Lake Shelters or Harvard Cabin.
• Posted  8:00 a.m., Friday, March 30, 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) 466-2858

2018-03-30