Avalanche Advisory for Saturday, March 24, 2018

Huntington and Tuckerman Ravine have LOW avalanche danger. All forecast areas have Low avalanche danger. Watch for unstable snow on isolated terrain features.

AVALANCHE PROBLEM: High temperatures in the low teen’s F, very firm snow surfaces and summit fog may have skiers dreaming about days of elevated avalanche danger today. Though climbers will appreciate the ease of climbing on the firm surface, skiers will be dealing with hard, fast conditions with no chance for softening snow. Light snow showers on light NW winds early this morning have created the illusion of fresh snow but don’t be fooled by the dust on crust effect. More snow showers today may create pockets of wind slab that will serve only to exacerbate the long sliding fall concern. For these reasons, expect low avalanche danger in all forecast areas due to new wind slabs this afternoon. Ice climbers should be aware that a climber fell up to their waist in the icy water behind an ice dam in Odell Gully yesterday. Expect the potential for an ice dam rupture to exist for a while on all ice climbs as spring continues and temperatures swing around the freezing point. Large chunks of ice are also beginning to appear on the floor of both Ravines.

WEATHER: Two inches of new snow may fall late this afternoon as a cold front pushes into the area today. Currently, the summit is in and out of the clouds at 10F with wind from the N at 11 mph. High clouds will thicken and lower through the day, bringing summit fog and challenging visibility, especially if snow showers develop later in the afternoon. All in all, today will play out like a mild winter day with the temperature struggling to reach above its current position. Relatively light NW winds should make travel above treeline more comfortable than usual.   

SNOWPACK: It’s been six days since any measureable precipitation fell on the summit besides the trace that fell overnight. Sixty-six inches of snow has fallen on the summit so far this month, accompanied by colder than normal temperatures, allowing our snowpack to bounce back a bit from the deficit we entered in January and February. There is currently 168cm of snow at the stake at the Hermit Lake snowplot, showing 5 cm of settlement since Thursday of what has remained a cold, dry snowpack at upper elevations. The 30” snowfall 10 days ago and 100mph+ westerly wind and avalanche cycle that followed, filled out most east and south facing slopes and runouts in an impressive way. For now, Ravines are in pretty good shape, though gullies on the right sides have top to bottom, but limited snow coverage. Snow surfaces most everywhere above treeline are very hard, but pockets of softer snow, some of it covered by a thick and grabby wind skin, exist in sheltered locations like the edges of gullies. This variability will keep you on your toes when skiing or climbing, especially considering the hard surface in most fall lines.

The Sherburne Ski Trail improved a lot after last week’s snowfall. Great coverage exists, though a bit of scouring may have exposed a rock or two in the usual wind hammered sections.

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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 7:50 a.m., Saturday, March 24, 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