Avalanche Advisory for Sunday, January 8, 2017

This advisory expires at Midnight tonight.

Huntington and Tuckerman Ravine have MODERATE avalanche danger. All forecast areas will have Moderate avalanche danger today. Natural avalanches are unlikely and human-triggered avalanches are possible. Heightened avalanche conditions exist on specific terrain features. Evaluate snow and terrain carefully to identify features of concern.

 Lower Snowfields and Little Headwall are not rated due to a lack of snow but look for overhead hazard in Lower Snowfields which remains mostly tree covered except beneath Duchess.

AVALANCHE PROBLEM: Currently, our snowpack is showing fair to good stability in most locations. Recent cold temperatures have created a weak surface snow structure of mostly loose snow over a finger hardness crust of variable thicknesses. Faceting around this crust and near the surface is likely to create unstable conditions if we receive the upper end of forecast new snow or wind loading as the day wears on. Potential heavy snow squalls with increasing northwest winds would drive our rating from where it sits at the upper end of Low and into Moderate in the afternoon depending on snowfall intensity and available snow on the ground. If in avalanche terrain today, keep a close eye on signs of wind loading and remember that visibility will diminish through the day. Wind slab on top of weak surface snow could propagate and possibly step down through the upper crust later today. Smaller pockets of old wind slab in steep terrain could also could be triggered in some locations this morning even before the arrival of new snow later.

WEATHER:  Skies are clear this morning with a current summit temperature of -16F. Northwest winds are blowing around 40 mph. Temperatures will rebound slightly during the day before falling again overnight and winds will remain from the NW and increase to the 45-60mph range. A trace to 2” of snow may fall during periodic snow squall activity this afternoon and evening. Forecast models indicate that this change in the weather will occur mid-afternoon but summit fog may descend during the afternoon hours.

SNOWPACK: Field work yesterday in a few locations shows that overall the upper snowpack remains well bonded to the now basal and super thick melt freeze crust with no sign of faceting on the crust. The two crusts closer to the surface are a different story. The weakest, faceted, sugary layer is associated with a crust 20-30 cm down. In most areas the surface snow is not very cohesive and doesn’t sustain a crack for any distance. Some more recent 1.5” of upslope snow is layered on top and though not cohesive it does add a bit to the load. It also contributes to the high quality skiing that many folks enjoyed yesterday in some locations. Safe travel, careful snowpack assessment and terrain management skills are necessary to safely enjoy the mountaineering options that exist now in our terrain. Crampons and snowshoes or skis are key equipment for a high traverse now.

The Lion Head Winter Route is open and the most direct route to the summit. Please be careful of bridge construction debris near crossover 7 on the Sherburne Trail when skiing or riding.

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 7:55a.m., Sunday, January 8, 2017. A new advisory will be issued tomorrow.

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

2017-01-08