Avalanche Advisory for Wednesday, January 25, 2017

This advisory expires at midnght.

Huntington and Tuckerman Ravine have MODERATE avalanche danger. Natural avalanches are unlikely and human-triggered avalanches are possible. Heightened avalanche conditions exist on specific terrain features. Evaluate snow and terrain carefully. Little Headwall and Lower Snowfields are not forecast due to thin snow cover.

AVALANCHE PROBLEM: Wind Slab formed Monday night into Tuesday on strong east winds. This wind slab will be found high in Pinnacle, Odell, South and Escape Hatch as well as Left Gully and Hillman’s Highway. Ice pellets likely rolled downhill, pooling around terrain features while freezing drizzle then fell widespread over the terrain. This added weight to the already formed wind slab, but also created a new surface for the next round of possible snow. If the higher end of snow forecast for today arrives (2”), expect new wind slab to form, creating the possibility for natural avalanches and exceeding our current rating.

WEATHER: While true rain never fell yesterday, the Summit recorded just about every other type of precipitation. All in all, over the past 36 hours, 1.5” of water fell, starting as snow, then pellets, then freezing rain, back to ice pellets and then finally back to light snow for a brief period overnight. Temperatures maxed out at 27F yesterday and winds calmed through the day and into the night. Current winds are NW at 30mph and the temperature is in the mid-25F. Lingering moisture in the air may bring snow showers today (a trace to 2”).The temperature will drop into the teens and winds will shift to the west, increasing to 60mph+ by the end of the day.

SNOWPACK: The snowpack is made of alternating layers of dry and wet snow at the moment. For today’s avalanche problem, the layers that formed starting Monday morning are of most concern. The warm period over the weekend was followed by a brief cold snap Monday morning. This created a thin crust, but one seemingly strong enough to create a bed surface. Roughly 5” of snow fell on this yesterday with a SWE of 1.5”. The storm started with strong east winds Monday into Tuesday, cross-loading north facing gullies and likely creating wind slab in the start zones. Visuals yesterday afternoon indicated east and south facing slopes avoided much of the loading. Ice pellets that fell yesterday have been scattered in all locations due to shifting winds. If snowfall accumulates today, expect winds to transport this and create new winds slab in lee areas of the steep terrain.

The Lion Head Winter Route is open and the most direct route to the summit from the east side of the mountain. Please be on the lookout for machine traffic on the Sherburne.

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  8:20a.m., Wednesday, January 25, 2017. A new advisory will be issued tomorrow.

Helon Hoffer, Snow Ranger
USDA Forest Service
White Mountain National Forest
(603) 466-2713 TTY (603) 466-2713