Avalanche Advisory for Tuckerman and Huntington Ravines


 Posted: 7:52 a.m., Saturday, December 30, 2006


 This is a GENERAL AVALANCHE ADVISORY. Use of the 5-scale danger rating
 system will begin when conditions warrant. Until then new advisories
 will be issued as needed. A General Advisory is issued when
 instabilities are isolated within the entire forecast area. However
 it's important to realize that avalanche activity may occur within
 these locations before the issuance of a 5-scale forecast. This is a
 critical fact to remember. Under a General Advisory you need to make
 your own avalanche stability assessments before venturing into any
 open slopes. Realize that snowfields may be developing on existing
 summer trails. Always check the latest avalanche advisory before
 heading into avalanche terrain.


 Since last weekend's rain which stabilized the snowpack at that time
 we have received 8.3" (21cm) of snow of varying densities on the
 summit. Some southern winds were associated with new loading earlier
 in the week, but most snow amounts were brought in on our prevailing
 NW and W winds. This all adds up to a changing landscape in the
 Ravines. New snow has made the mountain look like winter again, but I
 can't candy coat it we are still quite thin and behind schedule. With
 that said if someone wanted to find snow instability they could. We
 are getting closer to using the 5 scale danger rating system of "Low"
 through "Extreme", however the current situation still calls for a
 General Advisory as being most appropriate. Both Ravines saw lots of
 traffic yesterday with multiple snowfields getting new boot tracks.


 Climbers will often link sections of ice together by crossing small
 snowfields in Tuckerman. Based on winds, aspect, terrain and snowpack
 each small pocket will have varying degrees of stability. You must
 keep your avalanche eyes open and assess each new snowfield
 independently. It is critical that you focus on the consequences of
 what will happen to you if an avalanche occurs and not completely on
 their size. The majority of our snow coverage in the Ravines could
 only produce relatively small avalanches although the results would be
 dire if you were brought over rocks and cliffs. The Left Gully and the
 Chute have redeveloped quickly and are 2 of our largest snowfields on
 the mountain and based on size alone have the potential to create our
 largest avalanches.


 A clipper system is moving into the mountains as I type and we
 currently have flurries at Hermit Lake. The models differ considerably
 on the final snow amounts we are likely to receive over the next 24
 hours but 2-4" (5-10cm) is a safe bet. Winds out of the WNW will
 increase through the day gusting over 65 mph (105kph) this afternoon.


 New loading will occur as the day progresses so expect some isolated
 pockets of instability by late in the day. Your decision-making and
 route selection in avalanche terrain should also consider that it's a
 holiday weekend and more triggers are running around the mountain than
 usual. Always consider who may be above and below you!


 By now you should have refreshed your avalanche skills, installed some
 fresh high quality alkaline batteries in your avalanche beacon, and
 mastered its use. Don't forget your safe travel rules, techniques for
 assessing snow stability, and sign up for an avalanche course.


 Avalanche courses offered in the valley this winter are now on our
 website, www.csac.org.


 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, the HMC Caretaker at the Harvard Cabin, and the AMC at
 Pinkham Notch Visitor Center or Hermit Lake Shelters.


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