Avalanche Advisory for Tuckerman and Huntington Ravines


 Posted: 8:30 a.m., Friday, December 14, 2007


 Tuckerman Ravine has CONSIDERABLE and LOW avalanche danger today.


 Hillman's Highway, Left Gully, the Bowl, Headwall, and Lip have
 Considerable avalanche danger. Natural avalanches are possible and
 human triggered avalanches are probable. Be increasingly cautious in
 steeper terrain. Right Gully and the Little Headwall have Low
 avalanche danger. Natural avalanches are very unlikely and human
 triggered avalanches are unlikely except in isolated pockets. Normal
 caution is advised. The Lower Snowfields will remain "Not Posted"
 until they fill in with more snow. Forecasts for this location will
 begin when needed.


 Huntington Ravine has CONSIDERABLE and MODERATE avalanche danger.


 South, ODell, Pinnacle and Central Gullies have Considerable avalanche
 danger. Natural avalanches are possible and human triggered avalanches
 are probable. Be increasingly cautious in steeper terrain. All other
 forecast areas in Huntington Ravine have Moderate avalanche danger.


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


 Southern New Englanders are currently digging out from yesterday's
 storm but up north we're giving thanks for the few inches that we got
 as well. Sure, it would have been nice to receive a healthy dumping
 but then again it's these back to back small and medium accumulations
 that help us build up to the big monthly and seasonal totals. The
 Summit picked up approximately 3.1"(7.9cm) of 9.4% snow while Hermit
 Lake did even a little better measuring 4.9"(12.5cm) of 8% snow. Winds
 during the period of active snowfall were largely out of the WSW with
 12 hours in the 20-40mph(32-64kph) range. This allowed incoming snow
 to fall undisturbed in protected areas while a light soft slab
 developed on NE to E aspects. Today's weather will continue to add
 complexity to the snowpack as lingering snowshowers are accompanied by
 W winds up to 80mph(129kph). A couple of inches(5cm) is expected
 through the day. This combination will likely yield stiffer slab
 development around both ravines with E aspects raising the most
 concern. These new slabs will form over the top of soft slab,
 unconsolidated snow, existing hard slab and wind-hammered old surface.


 Try and remember that variety is the spice of life but it can also
 come back to bite you if you forget how pervasive and dangerous it can
 be! If we exceed the forecasted wind speeds or hover near 80mph for an
 extended period of time I wouldn't be surprised to see localized
 scouring of the relatively light density snow especially in parts of
 Huntington. Otherwise you should be on the lookout for increasing
 instability throughout the day with the possibility of natural
 avalanche activity on aspects in the direct lee of the day's winds.


 Some of the areas forecasted as Considerable currently fit the
 criteria for a Moderate rating but will reach their forecasted rating
 as the day progresses. As always keep an eye on the sky and make use
 of any clues that are thrown your way.


 We're watching the development of this weekend's storm very closely
 and you can bet I'll be looking at the latest forecast models as soon
 as I finish typing this. If you're thinking of heading up the hill
 this weekend make sure to check each day's advisory as well as the
 "Weekend Update" that will be availble on www.avalanche-center.org this evening.


 Start doing your snow chants and dances now!


 By now you've probably waxed your skis, sharpened your ice axes,
 refreshed your knowledge of stability assessment, and practiced your
 rescue skills. No matter how experienced we all are these skills fade
 with time. Now is the time to hone those skills. Your lives depend on
 it! We have all the avalanche courses offered in the valley this
 winter on our website, www.avalanche-center.org.


 The John Sherburne Ski Trail is open, with continuous snow from top to
 bottom. Many large waterbars and exposed rocks make this a challenging
 early season ski. The Lion Head Summer Trail is currently open. The
 change to the Winter Route will occur when snow conditions warrant.


 We'll let you know of the change when it takes place.


 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.


 Justin Preisendorfer, Snow Ranger
 USDA Forest Service
 White Mountain National Forest