| Posted: 9:32 a.m., Sunday, February 22, 2004 |
Huntington Ravine has MODERATE AND CONSIDERABLE avalanche danger. The Escape Hatch, South, Pinnacle, Damnation, and North Gullies have Moderate avalanche danger. Natural avalanches are unlikley and human triggered avalanches are possible. Use caution in steeper terrain. Odell's, Central, and Yale gullies have Considerable avalanche danger. Natural avalanches are possible and human triggered avalanches are probable. Be increasingly cautious in steeper terrain.
The summit received an additional 7.5cm (3in) of new snow in the past 24 hours. This brings the summit total to 12.5 cm (5in) in the past 36 hours. Winds shifted through the W and NW late last night and slowly increased through the early morning hours and are currently gusting to 90kph (55mph). The current snowpack situation is quite interesting and variable. The light 6.5% density snow that began the storm on Friday evening came in with light south winds. As winds increased so did snow density due to rimed stellars, spatial dendrites, columns, and very small high density snow grains. During this mid-day period we reached a high temperature of -3C (27F). Light snow picked up again after dark last night as winds began to shift as the low pressure moved over the area. By 10pm winds had moved through the west. Winds stayed very light remaining below 24kph (15mph) for the first 4 hours after the shift. As winds picked up, cohesive slabs began forming over light unconsolidated snow. Snow assessments this mornings revealed easy quality 1 (Q1) shears of light density soft slab failing on loose snow. This loose unconsolidated snow is layered above the high density slab deposited during the riming period mid-day on Saturday. We also found failures on the initial loose snow layer that came in at the beginning of the storm on Friday night. So we are most concerned about the "touchy" nature of the newly formed unstable soft slab over unconsolidated snow. Although we have received 12.5cm (5in) and are forecasted to pick up another 2.5-7.5cm (1-3in) we are more focused on how varing layers were deposited in lee areas. Particularly what we commonly refer to as an "inverted snowpack", when higher denisty snow is layered over lighter snow below. These are the conditions that concern us the most. Picking up a few inches a day rarely triggers thoughts of avalanche activity in many people. The eyes aren't as open compared to getting it all at once, but these are the conditions that can surprise you. The avalanche dragons are slowly creeping up on you...ever so softly... quietly opening his mouth...and then... WHITE FIRE! So keep your avalanche skills working today.
The John Sherburne ski trail has a coat of new powder over mostly hard pack conditions. Anticipate water ice and rocks lurking beneath the new snow. Though the surface looks good be prepared for these hidden hazards and sudden changes in the trail.
THE LION HEAD WINTER ROUTE IS OPEN. This is a steep and challenging route. Ice axe, crampons, and the skill to use them well are necessary for safe travel. Remember, it is always easier to go up than come down.
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 reading mountain weather's effect on the snowpack, and avalanche rescue.
| Please Remember: | ||
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Avalanche Advisory Archives.
United States Avalanche Danger Descriptions.
Échelle Canadienne de risque d’avalanche.
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