Latest avalanche advisory for Mount Washington’s Cutler River Drainage – Tuckerman and Huntington Ravines

Avalanche Advisory for Tuesday, February 9, 2016

This advisory expires tonight at 12:00 midnight.

All forecast areas of Tuckerman and Huntington Ravines have MODERATE avalanche danger.  Heightened avalanche conditions exist on specific terrain features. Evaluate snow and terrain carefully and identify features of concern. Lobster Claw, Lower Snowfields, and the Little Headwall are not posted due to lack of snow cover. Exercise caution in these areas.

AVALANCHE PROBLEM: Today there will be two primary avalanche problems competing for your attention, the establishment favorite wind slab, and the outsider candidate, loose dry avalanches. Dust on crust is an apt description of the current situation, with soft slabs expected to become a problem. The extent will be dependent on how much new snow the winds are able to transport into the ravines. Expect the slabs to be softer than usual for Mt. Washington. Any location where you find snow deeper than a few inches should raise a red flag in your mind. Previous to new snow, there were only a few older windslabs in strongly sheltered areas (such as the Lip) that harbored potential instabilities.

Loose dry avalanches may also be a threat, particularly in gullies where the terrain funnels snow into deeper, heavier masses of moving debris. Climbing routes in Huntington are prone to this problem being worse than more open snowfields found elsewhere.

WEATHER: A light, long-duration snowfall began yesterday afternoon and is tapering off this morning. So far, we have recorded 2.5” (6.5cm) of new low density (7.5%) snow at Hermit Lake. The summit is recording slightly more snow (3.7” or 9cm) with a very low density (2.5%). As snowfall began, winds were from the E around 30-40mph. They flipped to the W overnight and simultaneously dropped to single digit speeds. Today, we are expecting a modest increase in wind velocities coming from the NW. Additional snowfall today will be limited, with a trace to 2” possible.

SNOWPACK: For the most part, today’s problems are a result of the recent snow and expected increase in winds. Low density snow can easily be moved by light winds, so when winds reach into the 20-30mph range, you should be watchful for the development of new soft slab. These will likely be very soft, but will be cohesive enough to fracture as a slab. I don’t expect very large or destructive avalanches, but simply being knocked off your feet on the previously existing ice crust can be a harrowing experience.

Today is the first day we are putting a rating to the northern gullies in Huntington. This is due to the potential for loose dry avalanches as well as the potential for growth of soft slabs in the upper avalanche start zones. When the current active weather pattern changes, we may return to a “no rating” for these areas. But in the meantime, we want you to be aware that avalanche hazard may exist in these areas.

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 8:15 a.m. February 9, 2016. A new advisory will be issued tomorrow.

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

2016-02-09

Avalanche Advisory for Monday, February 8, 2016

Tuckerman Ravine has MODERATE and LOW avalanche danger.  Center Bowl and Chute 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, Lip, Left Gully 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 primary avalanche problem today. WSW winds the day before yesterday built wind slabs in wind sheltered, lee areas. These wind slabs were not particularly touchy, thick or widespread but still deserve caution. Moderate rated areas have the largest expanses of these wind slabs with low rated areas having similar slabs but to a more limited extent. Late in the day, new snow will reduce visibility and obscure surface snow, making it more challenging to stay on the older, more stable snow. Expect new snow starting this afternoon to lead to elevated avalanche danger overnight and into tomorrow.

WEATHER: Temperatures were in the upper teens F overnight with very light easterly winds. Cold northern air will move in and drop temperatures to the single digits F (5F/-15C) this afternoon with wind speeds rising to the 25-40mph range on the summit. A low pressure system passing well off shore will send snow showers our way this afternoon with bands of precipitation producing heavier snow after dark. Expect anywhere from 4 to 9” of new snow by tomorrow with more snow showers to follow through the day. Another low pressure system could produce more snow on Tuesday.

 SNOWPACK:  The old surface snow in the Ravines is the melt-freeze crust formed from the warm spell this past Wednesday and Thursday.  We found the crust to be 25cm thick and knife (K) hard.  Snow that fell on Friday, Saturday, and Sunday, about 3.3″, lies on top of this.  We found this newer snow forming a one-finger (1F) hard wind slab that varied greatly in depth, from close to 30cm thick to non-existent less than 5m away.  Shear quality was resistant but smooth (Q2) within the wind slab.  This slab began to form on lighter winds from the W and WNW on Friday, providing the weak layer for the slab that formed later on Friday through Sunday.  This wind slab is discontinuous in many areas like Left and Right Gully in Tuckerman as well as the Sluice and Lip.  The Chute and Center Bowl have the largest areas of this wind slab.  In Huntington, Central Gully has the most developed snowfield and also received the greatest amount of snow compared to the rest of the routes in Huntington.  Areas below the ice bulges of Pinnacle, Odell, and South will also likely harbor this wind slab, although these areas tend to offer easier alternatives to avoid instability.

An injury requiring litter evacuation occurred in Huntington Ravine yesterday due to a long sliding fall on the hard, old surface snow. Use caution, and a belay when necessary, on steep terrain. Self-arrest is not a substitute for a belay rope, particularly in hard snow conditions. The John Sherburne Ski Trail is passable, but just barely, with water ice being the dominant sliding surface. Expect very challenging, dust on crust, conditions later today.

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 8, 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

2016-02-08