Avalanche Advisory for Wednesday, April 12, 2017

This advisory expires at Midnight.

Huntington and Tuckerman Ravines have LOW avalanche danger. Natural and human-triggered avalanches are unlikely. Open water and thin snow bridges exist in the Little Headwall which may not be skiable.

AVALANCHE PROBLEM: Above freezing temperatures since Sunday night have led to settlement of our snowpack, however a risk of wet avalanches will remain through the day. Loose-wet avalanches, or sluffs, will be easy to trigger but manageable for the prepared. The water fall in the Lip is open now which is an indicator of the increased risk of wet slab avalanches. In the past, water flowing from the Lip/Headwall area has flowed between layers in the snow and triggered these heavy, water saturated slides. Either of the wet avalanche types can be surprisingly powerful due to the density of wet snow grains so continue to practice safe-travel techniques and consider rocks and cliffs in your runout. As temperatures continue to warm, spring hazards will take center stage as primary hazards. Undermined snow over deep holes, glide cracks, falling ice and rockfall are all emerging as primary hazards as spring arrives. Sloppy, post holing conditions exist anywhere the snow isn’t well packed. 

WEATHER: The current temperature on the summit is 39F with a west wind at 38mph. Anticipate similar temperatures and increasing wind speeds though the day with the summit in and out of the clouds. Rain showers this morning will give way to snow showers this evening as west winds increase to the 35-50 mph range and temperatures drop to the mid-20’s on the summit by midnight. Less than a ¼” of rain is likely early today with a trace to an inch of snow after dark.

SNOWPACK: Our snowpack has been exposed to above freezing temperatures for over 60 hours with a 3 hour period on the summit yesterday with a temperature of 50F. Overtime these temperatures create a uniform snowpack of rounded snow grains that eventually lead to good stability and a spring corn cycle. Freezing conditions at night are a key element for prime skiing, riding and climbing conditions since the refreeze makes for a more supportable and less sloppy snow surface, though some sun or warmth is needed to make soften it. Right now, an ice layer is lingering beneath the wind slabs which formed last Friday night and though we haven’t had anything other than skier triggered loose wet avalanches since then, the possibility for a stubborn slab releasing on that ice layer will remain for a while longer. Our snowpack is really deep right now despite the recent warm weather. Copious amounts of snow with few periods of thaw this winter have set us up for a great spring ski season, though todays warm and wet conditions are probably a good reason to pass on any invitation to ski or ride in steep terrain.

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. Be sure to check the date of the advisory when you read it!

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  7:30 a.m., Wednesday, April 12, 2017. 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

2017-04-12