Mar 282012
 

This advisory expires at midnight Wednesday, 3-28-2012

Tuckerman Ravine currently has Low avalanche danger. Natural and human triggered avalanches are unlikely EXCEPT IN ISOLATED TERRAIN FEATURES.  Read on concerning the potential for increasing avalanche danger.

Huntington Ravine is under a General Advisory. You will need to do your own snow stability assessments when using avalanche terrain in Huntington. A danger of falling ice exists, and will persist until it all comes down.

Between cold air and new snow it certainly seems like we won’t be losing much coverage this week.  As of dark yesterday evening the summit has picked up 5.5” (14cm) since Sunday.  The vast majority came on Monday along with very high winds.  The combination of high velocities and icy surfaces has kept new powder from adhering on a high percentage of open slopes.  Most of the new snow ended up deep in the woods as well as in the nooks and crannies of the highly textured spring terrain. Since about 11pm last night snowfall has waxed and waned with winds between 30-45mph (48-72kph).  The summit is reporting 3.3” (8.4cm) of snow over the past 8 hours with more potentially on the way.  A fast moving system could give us an additional inch, potentially two, through this morning before turning to a wintry mix this afternoon.  Expect pockets of new snow to develop, depending on actual accumulations, mostly in the high start zones of gullies and slopes.  Pay attention to how much snow falls, and loads, associated with the forecasted light to moderate winds before precipitation changes to a heavier type later today.  Mixed precipitation would add additional load to any slabs that develop. If we do receive 2+ inches (5cm) this morning and spend an extended period at the upper wind forecast of 50+ mph before decreasing we will move into MODERATE AVALANCHE DANGER.  The moguls, runnels, skier created platforms, and a plethora of natural Spring induced depressions will absorb and anchor the initial loading.  However, eventually the rough texture and structure of the terrain could be overwhelmed by new snow creating a new flat bed surface.  The current terrain has the ability to hold and absorb more snow amounts than the smooth conditions of midwinter, but I would be prepared for an increasing avalanche danger perhaps jumping over the fence from “Low” to “Moderate” if the upper end of wind and snow comes to fruition.  Also be prepared for a thin blanket of snow to hide some of the traditional spring hazards.

Due to frozen surface conditions long sliding falls are a significant threat to all mountain travelers in angled terrain. The slick icy surface will allow for rapid acceleration down slope potentially sending you into numerous obstacles below you.  Exposed rocks, chunks of ice, trees, and moguls that feel like rocks all make the sliding fall potential much more hazardous. Evaluate what a lost edge while trying to ski or board would mean. In many places the consequences for fast sliding falls are pretty grim. An ice axe, full 10-12 point crampons, and real mountaineering boots are absolutely critical for climbing in these conditions safely.  Because the current surface conditions have made most steep slopes “no fall” territory the experience and skills to use this equipment is imperative.  If you have to rent them I would think twice.

Undermined snow and crevasses have emerged in recent weeks. Overall, the worst of the crevasses can be found in the Sluice, through the Lip and into the Center Headwall. Undermined snow can be found in many locations, including Hillman’s and Left Gully. Cold temperatures this week have strengthened snow in relation to these issues, but you’ll still want to know where they are so you can avoid them. Realize falling into an open crevasse from above is potentially more likely due to the icy surface conditions and fog than when it’s soft and clear.  We recommend climbing up what you plan to descend so you can learn about these hazards.

Falling ice should remain in the back of your mind as well. Below-freezing temperatures generally pose less risk than very warm days, but the freeze-thaw cycles can work to dislodge rock and ice from steep terrain, sending it down onto anyone or anything in the runout.

The Harvard Cabin at the base of Huntington Ravine will be closing for the season this weekend.  Saturday night is the final evening for overnight accommodations.  The Sherburne Ski Trail is open about 1/3 of the way down.  There are a couple patches of bare ground and a stream crossing to negotiate before you get to the closure rope. There is a lot of newly frozen water ice on the hiking trails. Traction devices on your feet will be very helpful.

Please remember:

  • Safe travel in avalanche terrain requires training and experience. This advisory is just one tool to help you make your own decisions in avalanche terrain. You control your own risk by choosing where, when, and how you travel.
  • Anticipate a changing avalanche danger when actual weather differs from the higher summits forecast.  For more information contact the Forest Service Snow Rangers, the AMC at the Pinkham Notch Visitor Center, or the caretakers at Hermit Lake Shelters or the Harvard Cabin.  A new advisory will be issued tomorrow.

Christopher Joosen, Snow Ranger
USDA Forest Service, White Mountain National Forest
(603) 466-2713 TTY (603) 466-2856

3-28-2012 Print Friendly

 Posted by at 8:43 am