Avalanche Advisory for Friday, January 19, 2018

Huntington and Tuckerman Ravines have LOW avalanche danger. Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features. The Little Headwall is an open stream and is not rated.

 AVALANCHE PROBLEM: New snow in the last 48 hours has been pushed around by wind, leaving isolated pockets of wind slab where scouring to the old refrozen surface did not occur. Small avalanches in isolated areas might not have the potential to bury a person in the absence of a terrain trap, but such an avalanche could easily cause a long sliding fall. The hard surface that is still prevalent in our terrain would be difficult for even the most skilled to arrest a fall.

Potential for and consequences of a long sliding fall may be a greater concern as you travel in our terrain today. Microspikes are no substitute for crampons and ice axe. Your ability to travel in a controlled manner on steep snow using crampons and ice axe is a necessity in current conditions. A high speed slide towards rocks, cliffs, or other exposed hazards can easily have dire consequences.

 WEATHER: Temperatures pushed into the 20’s F on the summit yesterday under partial clouds and wind in the 20-40 mph range. Today looks largely the same regarding temperature and cloud cover, with wind that will increase to around 40 mph late today. We might see a trace of new snow. Wind will increase tonight and tomorrow, ultimately approaching 100 mph. Air temperature should approach 30F on the summit tomorrow, though the extreme wind will make it feel much colder.

SNOWPACK: New snow earlier this week struggled to stick to the hard refrozen surface as it was transported by wind. Pockets of new wind slab do exist but are largely small and avoidable. If you’ve tried to dig in our snow lately, you’ve noticed that the hard surface snow is tough to penetrate with any tool. Instability will be limited to snow above this refrozen layer for the foreseeable future. We’ve said it already today and have all week, but we continue to stress the hardness of the refrozen snow surface. It provides good purchase for crampons but is smooth enough to easily accelerate a small fall to a slide for life in steep terrain. You would be hard pressed to arrest such a fall.

The John Sherburne Ski Trail holds similarly hard conditions under a thin veil of newer snow and will only provide an enjoyable ski option for the most desperate skiers and riders.

Please Remember:
• Safe travel in avalanche terrain requires training and experience. This bulletin 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., Friday, January 19, 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

2018-1-19