Avalanche Advisory for Friday, February 28, 2014

This advisory expires at Midnight.

Tuckerman Ravine will have CONSIDERABLE and MODERATE avalanche danger. The Sluice, Lip, Center Bowl, and Chute will have Considerable avalanche danger.  Natural avalanches are possible and human triggered avalanches are likely. Conservative decision making and cautious route finding is essential.  Lobster Claw, Right Gully,  Left Gully, Hillmans Highway and the Lower Snowfields have Moderate avalanche danger. Natural avalanches are unlikely and human triggered avalanches are possible. The Little Headwall has Low avalanche danger. Natural and human triggered avalanches are unlikely.

Huntington Ravine will have CONSIDERABLE and MODERATE avalanche danger. Central Gully has Considerable avalanche danger. Natural avalanches are possible and human triggered avalanches are likely. Conservative decision making and cautious route finding is essential.   All other forecast areas have Moderate avalanche danger. Natural avalanches are unlikely and human triggered avalanches are possible. Evaluate snow and terrain carefully in Moderate rated areas, most of which are pushing the upper boundary of their rating.

AVALANCHE PROBLEMS: Wind slabs will again be the primary hazard today. These slabs formed from 2″ of light density (4.5%) snow blown in on 35-50 mph (55-80 kph) generally westerly winds. These windspeeds created windslabs in Considerable rated forecast areas that are likely on the touchy side. Avoid steeper areas of windloaded terrain and be alert for continued loading, especially early today.  Persistent slabs due to early faceting above and below the raincrust may contribute to recent wind slab avalanches making them larger than the more obvious surface layers. Slabs formed by sluffing snow beneath steeper pitches of ice and rock are also a concern. Protect yourself well before venturing onto these areas.

WEATHER: Approximately 6.5″ (11.5cm) of snow have fallen on the summit of Mount Washington in the past 4 days as low pressure spawned squall lines across the range. West-northweast winds this morning at 45-60 (70-95 kph) will decrease in speed to 35-50 mph (55-80 kph) and shift to the west. Unseasonably cold temperatures will challenge anyone today recreating in the mountains. High temperatures on the summit are forecast to top out at -15F (-26C) despite clearing skies and some sunshine. Looks like mitten and facemask weather will hang around through the weekend and into next week.

SNOWPACK: A natural avalanche the night before last in the center of Center Bowl about 70 cm thick ran out onto the floor of the ravine. Sluice, Lip, 75% of Center Bowl and Chute were all loaded with the same snow. Central Gully is also ripe with new loading. Clearing this morning may reveal more signs of natural avalanches that occurred last night as snowfall amounts appear to have exceeded forecast amounts. These areas of wind slab are resting on an ice crust which was found to have early stages of a weak layer of facets developing. Though hangfire in the Center Bowl kept me from approaching the crown, it appears as if the ice crust broke out under the wind slab load and then ran on top of the ice crust. The crown line was partially reloaded by yesterday morning and clearing today will give us a better indication  of last night’s loading based on the remains of the crown line. Beneath the ice crust was generally stable pencil hard windslab in the areas assessed from left of Lobster Claw over to the looker’s right edge of Sluice. Field work yesterday near Sluice came to a screeching halt when a large party entered the Ravine for photo ops on the debris pile and proceeded up into Lunch Rocks unaware of the existing hangfire hazard from Center Bowl and Lip not to mention from a Snow Ranger and his partner probing the edges of unstable slopes above. They followed no safe travel protocols, carried no avalanche safety gear and exhibited several classic “human factors”. I felt helpless, like a field biologist watching baby zebras being stalked by lions. If you’re reading this you are probably aware of the intersecting avalanche paths in the Ravines. If you choose not to educate yourself about avalanches, well, good luck with the lions.

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 Visitor Center, or the caretakers at Hermit Lake Shelters and Harvard Cabin. Posted 8:25a.m. 2-28-2014. 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

2014-02-28 Print friendly