Avalanche Advisory for Thursday, February 26th, 2015

This Advisory expires at midnight

Tuckerman Ravine has Moderate and Low avalanche danger. The Lobster Claw, Right Gully, Sluice, Lip, Center Bowl, and Chute have Moderate avalanche danger. Natural avalanches are unlikely and human triggered avalanches are possible. Left Gully, Hillman’s Highway, the Lower Snowfields, and Little Headwall have Low avalanche danger. Natural and human triggered avalanches are unlikely except in isolated terrain features.

All forecast areas of Huntington Ravine have Low avalanche danger. Natural and human triggered avalanches are unlikely except in isolated terrain features. Be aware of the potential for ice dams with recent very cold air in place.

AVALANCHE PROBLEM: Wind Slab continues to be the primary threat today. The areas from Tuckerman’s Sluice, through the Center Bowl, over to the Chute harbors the greatest slab problem. Other areas that are assigned a Moderate rating such as Right Gully and the Lobster Claw, as well as all areas rated at Low, have better stability overall and hold more options for avoiding unstable snow. Light snow showers are expected today which should not affect ratings, but could increase some sporadic instabilities in isolated terrain features.  Keep your eyes open for areas of thin new soft wind slab.

WEATHER: The higher summits will be mostly in the clear under cloudy skies today.  There is a slight chance of afternoon snow showers on a shifting and decreasing wind from 60 mph (96 kph) dropping to 20 mph (32 kph) later this afternoon. Temperatures will stay below 0F (-18C) and fall to -20F (-29C) overnight.  Generally, weather conditions won’t change much over the next week with very little potential for precipitation.

SNOWPACK: Yesterday, the summit recorded 0.7” (1.75cm) of snow during light morning showers.  Later today, additional snowfall may bring up to another inch (2.5cm) on falling wind velocities.  As already mentioned, this will not affect the designated danger rating for each forecast area, but may create some pockets of thin, new and isolated wind slab in very strong lee areas.  Watch for this issue, but this should only be a minor problem that will be easily mitigated if recognized.   Over the next couple of days, we will see how slabs may be changing during our field time.  However, with cold temperatures in place you can anticipate very slow changes in stability.  It will be quite likely you will see similar ratings through the weekend.

The most significant problem continues to be an avalanche stepping down into deep slabs that loaded in over the weekend and into Monday.  The bulls-eye is the E and SE aspects from the Sluice through Tuckerman’s Center Bowl.  I would give these areas respect and expect accurate stability tests to be difficult to get unless you are in the thick of it already exposed to avalanche hazard.  Snow pits on representative slopes down low, or on adjacent slopes, may give you “false stables”.

Areas rated Low in Huntington don’t have much for previously existing stability problems. They were scoured clean by strong winds Monday gusting almost to 100mph (162kph). The same can be said for Left Gully and Hillman’s. Right and Lobster Claw have a lot of firm stable snow and some sections of wind loading, so use your safe travel and snowpack assessment skills to help you avoid instabilities in these areas. Any unstable snow in the Lower Snowfields and Little Headwall will be confined to isolated terrain features, so if you go looking for the largest areas of snow here, don’t be surprised to find some avalanche potential.

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 8:00 a.m. Thursday, February 26, 2015. A new advisory will be issued tomorrow.

Christopher Joosen, USFS Snow Ranger

2015-02-26