9:54 a.m., Monday, December 9, 2002 TUCKERMAN RAVINE CURRENTLY HAS LOW, MODERATE, and CONSIDERABLE AVALANCHE DANGER. The Little Headwall, the Lower Snowfields, and Hillmans Highway have LOW avalanche danger. Natural avalanches are very unlikely and human triggered avalanches are unlikely EXCEPT IN ISOLATED POCKETS on steep snow covered open slopes and gullies. Normal caution is advised. Left Gully has MODERATE avalanche danger. Natural avalanches are unlikely and human triggered avalanches are POSSIBLE. Use caution in steeper terrain. All other areas have CONSIDERABLE avalanche danger. Natural avalanches are POSSIBLE and human triggered avalanches are PROBABLE. Be increasingly cautious in steep terrain. HUNTINGTON RAVINE HAS LOW AND MODERATE AVALANCHE DANGER. Central and South gullies have MODERATE avalanche danger. Natural avalanches are unlikely and human triggered avalanches are POSSIBLE on steep snow covered open slopes and gullies. All other gullies in Huntington have LOW avalanche danger. Natural avalanches are very unlikely and human triggered avalanches are unlikely except in isolated pockets on steep snow covered open slopes and gullies. Normal caution is advised. These pockets DO exist so put your avalanche skills to work in the Ravine. The summit received 4.2 inches of new snow in the past 24 hours while we picked up 5 inches here at Hermit Lake. Although the forecast called for clearing skies in the afternoon yesterday, moderate to heavy snow fell from 1:30 to approximately 7pm. This was associated with high winds peaking at 113 mph from the NW. These winds scoured some areas and loaded others. Tuckerman once again picked up significant amounts of new snow which generated a natural avalanche in the strong lee under the center ice on the Headwall. It was about 120 ft long and about 12 inches deep. I believe this occurred sometime been 9pm last night and 5 am this morning. The south end of Tuckerman Ravine near the Chute has more stability than the Northern end near the Lip and the Sluice. The north end in strong lee areas of NW winds picked up the most snow. If these areas did avalanche overnight evidence has been erased by more blowing snow and high winds. Falling temperatures fell to -23 degrees F on the summit overnight. Here at Hermit Lake we dropped 40 degrees in 12 hours as the front pushed through. New snow and extreme temperatures has brought a strong temperature gradient in the upper snowpack. We will be watching for near surface facets through recrystalization which may become a weak layer in the near future. I think if it does become an issue it won't be wide spread due to significant variability in new snow depths in different areas due to high winds. These various depths will present different temperature gradients therefore different rates of crystal change. Thin pockets may offer rapid facet growth before warming temperatures move back midweek. That grapel layer is getting buried deep which will decrease the chance of it being human triggered. However, if an avalanche occurs on a weak layer above it may step down to this layer and rip it out as well. We were finding quality 1-easy to moderate shears between layers of hard slab. A few things are important to keep in mind about this situation. Grapel with high winds will often pool in lee areas and will not be uniformly distributed. Some areas may have no grapel layers while certain pockets may have heavy deposits. This variability should be kept in mind. Particularly in relation to potential weaker trigger points when a slope might be skied more than once. One set of ski tracks doesn't mean the slope is OK. However, we found the tensile strength of the hard slab above this weak layer to be quite strong. This strength will be higher on smaller slopes with multiple anchor points still helping hold slabs in place. This 'bridging' over weak layers will becomes less of a stabilizing factor as you move onto larger open slopes such as the center bowl of Tuckerman. THE LION HEAD SUMMER TRAIL BELOW TREELINE HAS BEEN SHUT DOWN FOR THE WINTER DUE TO THE STEEP SNOWFIELD TRAVERSE NEAR TREELINE. THE SUMMER TRAIL AREA WILL AVALANCHE WITH ENOUGH NEW LOADING THROUGH THE WINTER. THE WINTER LION HEAD ROUTE IS NOW OPEN. IT LEAVES FROM THE HUNTINGTON FIRE ROAD AND HAS ORANGE SIGNS STARTING ON THE TUCKERMAN RAVINE TRAIL AT ROUGHLY THE 1.8 MILE MARK. IT IS STEEP AND CHALLENGING, CRAMPONS, AN ICE AXE, AND THE ABILITY TO USE THEM WITH SKILL ARE REQUIRED FOR SAFE TRAVEL. As I read the articles in print media about the avalanche accidents one major myth or misunderstanding was a constant theme in headlines. "UNPREDICTABLE SLIDE STRIKES" or "MOVING MASS CAPTURES CLIMBERS WITHOUT WARNING" are 2 examples of the average captions. There will always be surprises in the natural world as Mother Nature throws infinite amounts of variables at us. Look at the snowflake. No two are exactly alike which means no bond between crystals is exactly alike. Knowing this, every time we check for instability the weak layers will be at least a bit different. This is the reason that avalanche forecasting and stability assessment is a blend of art, intuition, past experiences, and science. Even the most experienced forecasters will be surprised many times through their career. This is OK, it keeps us all humble and striving to learn more about the natural world. However, saying this we have also come an incredible way over the past 50 yrs to understand AND FORECAST this natural phenomenon. You, your backcountry pals, and I have the tools at our disposal to predict avalanches MOST of the time. Good avalanche courses and time in the field will make you better and better at making these predictions. Sign up for an avalanche course. We have all the avalanche courses offered in the valley this winter on our website, csac.org. If you decide not to take the time to learn this blend of art and science than for you the avalanche will strike without warning. REMEMBER AVALANCHES ARE PREDICTABLE MOST OF THE TIME. AS ALWAYS, THIS ADVISORY IS ONE MORE TOOL TO HELP YOU MAKE YOUR OWN DECISIONS IN AVALANCHE TERRAIN. It should be used along with your own snow stability assessments, knowledge of safe travel techniques, skill in mountain weather's effect on the snowpack, and avalanche rescue. PLEASE REMEMBER: o Any new precipitation may increase the avalanche danger, this includes wind transported snow. o Obtain latest weather forecast before starting out. o For more information, contact the U.S. Forest Service Snow Rangers: AMC at Pinkham Notch Visitor Center or Hermit Lake Shelters. o This avalanche bulletin will expire at midnight. Christopher Joosen, Snow Ranger USDA Forest Service White Mountain National Forest