Avalanche Advisory for Tuckerman and Huntington Ravines


 Posted: 8:30 a.m., Thursday, January 17, 2008
 Tuckerman Ravine has LOW avalanche danger today. Natural avalanches
 are very unlikely and human triggered avalanches are unlikely EXCEPT
 IN ISOLATED POCKETS. Normal caution is advised. THESE ISOLATED POCKETS
 DO EXIST. Read the discussion below for clarification.


 Huntington Ravine has LOW AND MODERATE avalanche danger today. The
 Escape Hatch, South and Odell's gully have Low avalanche danger.


 Natural avalanches are very unlikely and human triggered avalanches
 are unlikely except in isolated pockets. Normal caution is advised.


 All other forecast areas in Huntington have Moderate avalanche danger.


 Natural avalanches are unlikely and human triggered avalanches are
 possible. Use caution in steep terrain.


 High winds yesterday morning did a bit more scouring than loading in
 both Ravines although snow did get shuffled around a bit in avalanche
 terrain. What we have left is the old rock hard surface as the
 dominant feature in Tuckerman and Huntington Ravines. With this said
 there are pockets that are holding on to some unique instabilities.


 All forecast areas in Tuckerman are posted at Low because of the
 straight forward travel options you have by staying on the old
 surface. The pockets that are present are still quite touchy, but
 generally they are small and thin. The fracturing we witnessed two
 days ago in these locations failed on a nearly imperceptible interface
 between the thin soft slab and the unconsolidated snow sitting on the
 old surface. Triggering one of these isolated pockets should not be a
 surprise as they are obvious even by their color difference from far
 away, clean white being soft new snow and the dirtier looking hue
 being the old icy surface. Locations in and below the Lip, through the
 Sluice, and over to Right Gully contain some good examples of these
 new snow slabs. Stick to the old surface for safe travel and be aware
 of any one above you that may be in these isolated areas of
 instability. In Huntington some forecast areas are posted at Moderate
 due to the wall to wall nature of the new snow which eliminates
 options for skirting around them. Again they are thin albeit touchy in
 nature, many would have the mass to knock you off your feet so be sure
 to protect any new snow areas well with rock and ice gear.


 Winter weather is coming back for the MLK weekend. A WINTER STORM
 WATCH is in effect beginning very late tonight with 6+ inches
 anticipated for the mountains. Winds will begin from the south before
 wrapping from a westerly direction and increasing through tomorrow. We
 would not be surprised if we hit 100mph by dark on Friday. This will
 crank up instability tomorrow with new loading so expect an elevated
 avalanche danger with the results of this system. The second winter
 slap will come in the form of Arctic air. Temperatures on the summits
 should be below zero F for the weekend culminating with low
 temperatures on Monday of around -25F. 
 Until we have enough new snow to make the hard surface conditions a
 memory, you will need crampons, an ice axe and solid self arrest
 skills to travel safely in steep terrain. This includes travel on the
 Lion Head Winter Route. The Sherburne Ski Trail has hard pack
 conditions with some skied up new snow on the surface.


 Please Remember:
 o It is impossible to accurately predict natural events, such as
 avalanches, in every instance. This Advisory is one tool to help you
 make your own decisions in avalanche terrain. It should be used along
 with safe travel techniques, snow stability assessments, an
 understanding of weather's effect on the snowpack, and proficiency in
 avalanche rescue.


 o You should obtain the latest weather forecast before heading into
 the mountains. Anticipate a changing avalanche danger when actual
 weather differs from the National Weather Service forecast.


 o For more information, contact the U.S. Forest Service Snow
 Rangers or the AMC at Pinkham Notch Visitor Center or Hermit Lake
 Shelters or the HMC caretaker at the Harvard Cabin. This advisory will
 expire at midnight.


 Christopher Joosen, Snow Ranger
 USDA Forest Service
 White Mountain National Forest