Avalanche Advisory for Wednesday, April 16, 2014

Tuckerman Ravine has Low avalanche danger. Natural and human triggered avalanches are unlikely.

Huntington Ravine is under a General Advisory. You will need to do your own snow stability assessments when traveling in avalanche terrain in Huntington. A danger of falling ice exists, and will persist until it all comes down.

AVALANCHE PROBLEM: Plunging temperatures overnight are freezing our snow pack and beginning to lock up free water. A small amount of new snow (<1″) with continued upslope snow may create small pockets of unstable Wind Slab in lee areasThis morning, high winds are likely scouring high start zones and depositing snow lower in the Ravines. As winds slow later, look for the potential for wind slab development in higher start zones. Monitor the amount of new snow fall today and anticipate a potentially growing hazard, particularly if more upslope snow falls than is forecast.

WEATHER: The summit temperature graph was bearish last night, to say the least. Temperatures dropped to -2F (-19C) from a steady 40F (4C) last night at 6pm. Cold frontal passages like the one we are experiencing often spawn upslope snow shower activity on the mountain, though the Obs is only calling for a trace to one inch (2.5cm) of new snow today. Winds are blowing pretty steadily around 90 mph (115 kph) this morning. NWS point forecast is for 115 mph (185 kph) gusts this morning. Either way, it is pretty darn windy out. NW winds should fall off to 30-45 mph (50-70 kph) by sunset with clearing skies and temperatures rebounding a bit to the mid-single digits F (+/-  -15C).

SNOWPACK: To sum it up, hard and icy everywhere and undermined in many areas. If weak layers deep in the snowpack remain intact after the warm spell, they will be thoroughly bridged over by a icy skin of frozen slush and cold hard slabs of melt forms in the upper layers. The 2.18″ of rain that fell in the past 36 hours have opened waterfall holes and crevasses and undermined snow bridges covering water channels. Despite the cold, water is still flowing and continuing this process so if you venture into the Ravines be aware of the potential for punching through into these voids which can be surprisingly deep. Some thin areas in Right Gully and Sluice and areas over high volume water courses like the Lip and Center Bowl could collapse. The Little Headwall is now a waterfall. The Lip/Center Bowl waterfall hole and a crevasse along the base of the ice opened up on Monday and likely grew yesterday. I wouldn’t be surprised to see a slot lower near the top of the Open Book when visibility improves later today.

OTHER HAZARDS:  Today, we are standing at the busy intersection of winter and spring hazards. Cold temps and high winds coupled with open waterfall holes and icy trails make travel in the mountains challenging. Recent rain and warm weather really melted out snow spanning streams like the one that flows out of Tuckerman. With our deep snowpack, the distance from snow surface to rushing streambed below could make it difficult to climb out of some of the holes.

Micro-spikes and other creeper style traction devices may be helpful on some lower angle trails, but they do not provide the security of crampons. Be prepared to handle steep, firm snow and fast, icy surfaces. A fall on steep terrain today would be next to impossible to self-arrest. Don’t fall today, especially above a crevasse or streambed.

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.
  • Posted 7:55 a.m. 4-16-2014. 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

2014-04-16 Print friendly