Avalanche Advisory for Saturday, January 18, 2014

This advisory expires at 12:00 midnight.

Tuckerman Ravine has Moderate and Low avalanche danger. The Sluice, Lip, Center Bowl, Chute, Left Gully, and Hillman’s Highway will have Moderate avalanche danger. Natural avalanches are unlikely and human triggered avalanches are possible. All other forecast areas have Low avalanche danger. Natural and human triggered avalanches are unlikely.

All forecast areas of Huntington Ravine have Moderate avalanche danger. Natural avalanches are unlikely and human triggered avalanches are possible.

AVALANCHE PROBLEM: Storm Slabs forming this afternoon and evening are the primary avalanche problem. We are expecting snow to begin in the late morning and we may possibly have periods of heavy snowfall in the afternoon. This will cause avalanche danger to increase through the day, especially late. It should rise enough that it will be possible for you to trigger an avalanche in most areas of both Tuckerman and Huntington Ravine.

WEATHER:  Weather over the next 24 hours, specifically precipitation amounts, has been a little tough to pin down. The NWS has called the low pressure moving up the coast a “vigorous disturbance” which is expected to deliver snow to our region ranging from 2-6+” (5-15+cm). Mt. Washington is very close to a boundary between less snow to our N and W and more to our S and E. Snow squalls may set up producing brief periods of intense snowfall rates late today. Winds are anticipated to remain rather placid, which will limit substantial loading until Sunday when they shift to the NW and W and increase in speed. Though snowfall rates are expected to taper somewhat, snow will continue tonight and tomorrow giving us additional inches to deal with for Sunday’s avalanche problems. We expect a significant loading event Sunday, creating widespread avalanche problems.

SNOWPACK: Field observations yesterday gave us a good baseline for what the new snow today will be landing on. Across much of Tuckerman, there was a patchwork of old crusty surfaces and thin coverage of new snow. If it were not for new snow arriving today, all forecast areas would be rated Low today with a discussion of isolated areas of unstable snow. Huntington had a more consistent blanket of new snow and less old surface than Tuckerman, which is unusual. The old crust is as stable as stable can be. The new snow on top of the crust had good stability for the most part, but will act as weak layer of snow beneath today’s accumulations.

Today’s accumulation is the concern that is driving the Moderate rating in many areas. The most likely scenario is that we get a few inches with light E winds. In this scenario most areas will be slow in rising into the Moderate realm. However, weather forecasts have enough suggestive language related to locally higher amounts that we can’t ignore. If we reach or exceed the upper end of the forecasted snow totals (i.e. if we receive 3-5″ during the day and more after dark), new soft storm slabs will be forming. Easterly winds can be tricky on our side of the mountain. With the forecasted speeds being so light, you may not even realize the soft snow you’re walking through has the ability to act as a slab. Be wary of these, as well as of areas where snow has sluffed off from steeper slopes or ice pitches above. These sluff piles can form into deeper, denser slabs and have been responsible for many climbers unexpectedly finding themselves moving downslope in an avalanche.

OTHER HAZARDS:  There is still a lot of ice and hard crusts out there hidden by a veneer of new snow. Ski poles and various foot traction will be helpful getting to Hermit Lake or the Harvard Cabin. Crampons and an ice ax are essential for travel in steeper terrain.  The Lion Head Winter Route has limited snow cover, so it is a very steep icy mountaineering route at this time. Expect crowded slow moving conditions as people try to negotiate the steep sections safely.

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 8:30a.m. Saturday 1-18-2014. 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

2014-01-18 Print Friendly