Avalanche Advisory for Sunday, February 7, 2016

Tuckerman Ravine has MODERATE and LOW avalanche danger.  Lip, Center Bowl, Chute and Left Gully have Moderate avalanche danger. Natural avalanches are unlikely and human-triggered avalanches are possible. Evaluate snow and terrain carefully to identify features of concern.  Right Gully, Sluice and Hillman’s Highway have Low avalanche danger. Natural and human-triggered avalanches are unlikely. Watch for unstable snow on isolated terrain features. 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 Gully has Moderate avalanche danger.  Natural avalanches are unlikely and human-triggered avalanches are possible. Pinnacle, Odell and South have Low avalanche danger. Natural and human-triggered avalanches are unlikely. North, Damnation, Yale, and the Escape Hatch are not posted due to lack of snow cover. Exercise caution in these areas and expect the potential for isolated patches of instability.

AVALANCHE PROBLEM: Wind slab is the avalanche problem today. WSW winds yesterday built wind slabs in sheltered areas. The underlying softer snow which fell on Friday is the weak layer in these surface slabs which are not likely to be particularly touchy or thick in most areas. The terrain in our strongest prevailing lee locations such as Odell and Pinnacle in Huntington and Center Bowl and Left Gully in Tuckerman are still lacking the snow coverage needed to harbor large continuous slab. That said, I would approach these areas cautiously until you identify the nature and location of these wind slabs. Use caution when moving around in the Ravines today. Steep terrain features with patches of somewhat unstable snow and rocky runouts should still command respect. Also, remember the number of human triggers that will be around on a busy weekend.

WEATHER: Over the past 48 hours, 2.5” of new snow fell on the summit. Two days ago the most intense period of snow fell on light winds from the W and WNW. Later that day, wind speeds ramped up to the 60 to 70 mph range. Yesterday another half inch of snow fell on moderate (40-50 mph range) from the WSW. Currently, W winds near 70mph are blowing on the summit with snow showers which may drop another 1” of snow. Winds should calm down through the day though visibility will remain difficult with summit fog under mostly cloudy skies hanging around. Temperatures will hold steady in the low to mid-teens F.

SNOWPACK: New wind slabs are sitting on a firm bed surface of hard melt freeze crust from the penetrating heat that punished our snowpack on February 3rd and 4th. You will find this crust mostly supportable and hard in wind exposed areas in open terrain. In more wind sheltered locations, along gully edges and below tree line, you will punch through that layer into faceted, soft snow. The melt freeze crust that developed on pre-existing wind slab is pretty darn hard (P) and as a result isn’t currently a concern as a stability issue. Two days of temperatures near 10 F have not improved the stability of the top most wind slabs which is unlikely to produce anything much larger than a D1 avalanche. It goes without saying that even a smaller slide can be dangerous in our steep terrain on a fast bed surface that requires lightning fast reflexes with your axe if you hope to arrest a fall.

The Lion Head Winter Route is open and is recommended for those opting to avoid avalanche terrain. Microspikes and ski poles are helpful on lower elevation trails, but are not substitutes for crampons and an ice axe on routes at or above treeline. The John Sherburne Ski Trail is passable, but just barely, with water ice being the dominant sliding surface. Expect very challenging conditions.

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. February 7, 2016. A new advisory will be issued tomorrow.

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