Avalanche Advisory for Friday, 2-15-2013

This advisory expires at 12:00 midnight, Friday 2-15-2013

Tuckerman Ravine has LOW and MODERATE avalanche danger.  Lobster Claw, Right Gully, Left Gully, Hillman’s Highway, Lower Snowfields, and the Little Headwall have Low avalanche danger. Natural and human triggered avalanches are unlikely.  Sluice, Lip, Center Bowl, and Chute have Moderate avalanche danger. Natural avalanches are unlikely and human triggered avalanches are possible.

Huntington Ravine has LOW and MODERATE avalanche danger. North, Damnation, Yale, South, and Escape Hatch have Low avalanche danger. Natural and human triggered avalanches are unlikely. Central, Pinnacle, and Odell have Moderate avalanche danger.  Natural avalanches are unlikely and human triggered avalanches are possible.

Though less than ideal weather conditions exist today for skiing, generally good stability could yield nice skiing and riding  in Tuckerman Ravine today for those willing to lower their standards a bit.  Our snowpack is still shallow for this time of year so lots of ice is showing in the headwall and Sluice and lots of bushes will limit you to short radius turns in Lobster Claw, Right and lower in Left Gully. Safe travel techniques when skiing will be challenging due to limited visibility, due to fog and a trace to 2″ (5cm) of new snow coming and may necessitate short pitches of skiing in order to maintain “eyes on” your partner. Climbers will find lots of ice trending to the “fatter” side in Huntington Ravine gullies.

Pockets of pooled, heavily rimed snow crystals are the areas of concern in both ravines today. Though not widespread, you will find areas of windslab on top of the weak rimed interface that are reactive to a moderate to hard trigger.  If you stumble into a larger, deeper area of this slab, you could trigger a consequential avalanche.  Yesterday, Chris and I observed several reactive layers, varying in depth from 6″-12″ (15-30cm), created by changes in snow density. These weak interfaces are probably deeper, perhaps significantly, in places.  Stay tuned in to the qualities of the upper layer(s) of snow and be alert to changing cohesion and reactivity of the slab.  Cracks shooting out more than a foot or so are a warning sign to remind you to manage the hazard by either tweaking your route to avoid the slab or finding and placing pro.

Boot penetration averages around 25 cm with deeper postholing in the faceted areas around rocks and bushes. Additionally, old rain crust is showing in spots and harder windboard exists in others. There was strong solar gain in the upper 4″ (10cm) of the snow on steep south facing terrain that moistened the snow and helped the stability process but created a bit of sun crust today.  Be sure to check our Weekend Update later today or this evening for more information about the busy upcoming holiday weekend.

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 the Harvard Cabin.
  • Posted 8:35a.m. Friday 2-15-2013. A new advisory will be issued tomorrow.

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

2013-02-15 Print friendly