Avalanche Advisory for Tuesday, February 24, 2015

This advisory expires tonight at 12:00 midnight.

Tuckerman Ravine has Moderate and Low avalanche danger. Lobster Claw, Right Gully, the 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. Watch for unstable snow in isolated terrain features.

All forecast areas of Huntington Ravine have Low avalanche danger. Natural and human triggered avalanches are unlikely. Be aware of the potential for ice dams today.

AVALANCHE PROBLEM: Avalanche problems in our forecast zones today are largely confined to Tuckerman with very few potential problems in Huntington. Wind slab is the primary threat. Recent wind-loading has triggered natural avalanches on some slopes, which is considered “bulls-eye” information pointing toward instability. The Sluice, Lip, Center Bowl, and Chute in Tuckerman are the areas with the greatest potential for avalanches. We are beginning to see and hear of avalanches and/or unstable snow conditions outside of our forecast areas, so pay attention whenever you are near potential avalanche terrain.

WEATHER: In the last 7 days, the summit has recorded 16.5” of new snow (42cm). More than this has been recorded at our manual snow plot at Hermit Lake. Yesterday, strong NW winds blew at an average speed of 71mph (114kph) with a peak gust of 98mph (155kph). Today, wind speeds will be much more manageable, decreasing through the morning but increasing again in the afternoon. Temperatures will remain very cold; in the ravines you can expect temperatures hovering around 0F (-18C).

SNOWPACK: A quick visual scan of Tuckerman this morning gave me goosebumps. It’s amazing how quickly the Sluice, Lip, and Center Bowl have grown to a size that should make anyone stop and stare for a moment or two. There is currently a lot of snow loaded into these slopes and it has not been shedding it off regularly in avalanches as it often does. The net effect is a deeply layered snowpack capable of producing a very large avalanche. The snow on these slopes is also well-connected from one path to another, which allows a single fracture to propagate across multiple avalanche paths. You might be wondering about the stability of the snow here. Well, so am I. We tend toward conservative decision making, especially when consequences are high, so you won’t find me center-punching a bootpack up the Lip or headwall today. Although I don’t have hands-on information to give, I have a lot of confidence in the potential for a person traveling through here to trigger an avalanche.

Right and Lobster Claw have a much different snowpack. Expect areas of new windslab with some reasonable options for climbing and avoiding much of the troublesome snow (but not all). The Chute has reloaded in the zone between the choke and the upper rollover. Left Gully and Hillman’s were scoured pretty heavily. The Lower Snowfield has a lot of “isolated terrain features” that can have unstable snow. In the Little Headwall, there is a lot of windblown snow. I recommend going cautiously through here if you are one of the first today. I observed fresh crown lines this morning on the Lion Head Trail (summer traverse) and in the Gulf of Slides south snowfields.

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 8:15a.m. February 24, 2015. A new advisory will be issued tomorrow.

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