Avalanche Advisory for Friday, February 12, 2016

Tuckerman Ravine has CONSIDERABLE and MODERATE avalanche danger.  Sluice, Lip, Center Bowl, Chute and Left Gully have Considerable avalanche danger. Natural avalanches are possible and human-triggered avalanches are likely. Careful snowpack evaluation, cautious route finding and conservative decision making are essential. Right Gully and Hillman’s Highway have Moderate avalanche danger. Natural avalanches are unlikely and human-triggered avalanches are possible. Evaluate snow and terrain carefully to identify features of concern. Lobster Claw, Lower Snowfields, and the Little Headwall are not posted due to lack of snow cover.

Huntington Ravine has MODERATE and LOW avalanche danger. Central, Pinnacle, Odell, South and Escape Hatch have Moderate avalanche danger. Natural avalanches are unlikely and human-triggered avalanches are possible. North, Damnation and Yale have Low avalanche danger. Natural and human-triggered avalanches are unlikely. Exercise caution in these areas and expect the potential for isolated patches of instability.

AVALANCHE PROBLEM: It is hard to miss the crown line stretching from Chute across the Center Bowl to Lip even in the reduced visibility this morning. Recent avalanche activity is one of the red flags that indicate the threat of unstable snow. Sign of wind transported snow is another. Both of these exist this morning making wind slab the primary avalanche problem.  Strong northwest winds are continuing to load snow into lee areas and reload our avalanche start zones, filling in crown lines and further stressing hangfire with the weight of more snow. Winds will diminish this afternoon indicating a slight downward trend in avalanche danger ratings.

WEATHER: After a three day period of low wind speeds and light but steady snow shower activity yielding 9” of snow, winds ramped up yesterday to speeds ideal for loading snow into our avalanche start zones. A haze of wind transported snow still dominates the ridgelines. The mercury bottomed out at -27F just after midnight last night and has rebounded to -20F on the summit. Expect a cold day with a high near -10F with winds shifting to the west and diminishing from where they stand in the 60 mph range down to the 30 mph range later in the day. Visibility may be reduced by afternoon clouds and summit fog with some snow showers becoming possible.

 SNOWPACK:  Wind came close to reaching speeds that tend to scour out the higher elevation and less protected gullies in Huntington Ravine for a brief period of time last night. The northern gullies remain mostly ice at this point but with some obvious slabs visible in the mid-elevation choke point of Yale and Damnation Gully. We have not yet observed the other gullies in the Ravine but it is likely that they have reloaded, or are currently reloading this morning. A shift in winds tends to pickup and move snow from drifts formed by another wind direction so I would expect the loading will continue for most of the morning. If you are braving the frigid temperatures, be sure to look for wind loaded slabs in Central through the southern gullies. Some of these slabs may be on the softer side of stubborn. It is likely that many areas were scoured right down to the pre-existing icy, melt-freeze crust from the Feb 3rd and 4th warm-up so be prepared for fast, hard surface conditions for sliding as well as marginal adhesion of newly blown-in snow. Hollow sounding slabs and cracks in the surface snow are indicators of potential instability so be on the lookout for these and test slopes cautiously. For all the recent snowfall and avalanche activity, our snowpack remains very lean with lots of rocks and ice cliffs to create opportunities for injury in a sliding fall.

The John Sherburne Ski Trail has improved but be careful of stretches of ice lurking beneath wind affected surface snow. The Winter Lion Head Route is open and remains the best east side route to the summit that avoids avalanche terrain.

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 8:25 a.m. February 12, 2016. 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