Avalanche Advisory for Saturday March 16th, 2013

Expires at midnight

Tuckerman Ravine has High and Considerable avalanche danger.  The Sluice, Lip, Center Bowl, and Chute have High avalanche danger.  Natural avalanches are likely and human triggered avalanches are very likely. Very dangerous avalanche conditions exist and travel in avalanche terrain which includes runout paths is not recommended.  The Lobsterclaw, Right Gully, Left Gully, Hillman’s Highway, and the Lower Snowfields have Considerable avalanche danger.  Natural avalanches are possible and human triggered avalanches are likely. The Little Headwall’s main hazard is the deep long trench from top to bottom down the middle now hidden by new snow. A Lion trap is a good name for it.

Huntington Ravine has Considerable avalanche danger.  Natural avalanches are possible and human triggered avalanches are likely. Dangerous avalanche conditions exist making conservative decision making essential. The Escape Hatch has Moderate avalanche

Since 4pm yesterday Hermit Lake has received 7.2” (18cm) of champagne 3.8% density fluffy snow, while the summit picked up almost exactly the same collecting 7.3”.  It is currently still snowing with large stellars being the dominate crystal. We expect upslope snow to continue until late morning or early afternoon adding a bit more to the landscape. So what we are dealing with this morning is an increasing avalanche danger due to 14.5” of snow over the past 48 hours with moderate to high wind speeds. 

During our field time in both Ravines Friday afternoon we found very different situations, with Huntington Ravine having more scouring than Tuckerman. In Tuckerman we found a number of alarming stability tests with compression test and extended column test scores as low as CT2 and ECTV. (See our youtube posting on “the Pit” and the “Weekend Update” for details)  It doesn’t get much more startling than that.  The weaknesses we found were a consistent theme with stronger slabs in pockets of deeper slab.  We travelled where we safely could to find the best overall representative stability impression of the entire Ravine.  We moved through Chicken Gully, low in the Sluice, Right Gully and towards the bottom of the Lobsterclaw.  Based on the hazard, there was no way we could safely get to the area of most concern, above Lunch Rocks up towards the Lip and the Center Headwall. We were generally finding pencil to 1 finger hard slabs on a weak loose unconsolidated layer of intact snow crystals all sitting on the hard icy rain crust.  Over towards Left Gully, Hillman’s Highway, and the Lower Snowfields instabilities were less and mostly limited to sections of the upper start zones.

Today’s 7.3” (18cm) of low density snow is now being loaded over the weak layer that we found yesterday.  NW winds gusting into the 60-65mph (97-105kph) range is now moving last night’s snow into both Ravines, layering either on the old icy surface or recent slabs of varying weakness.    Winds will shift from the W and fall in velocity this afternoon, but not before loading new aspects. Today’s overall loading will set up another upside down scenario with denser slabs over weak loose snow giving us multiple weak layers. This could cause an avalanche to step down into deeper layers.  Visibility will also be limited today which will keep you from seeing either the terrain, or all the weekend travelers, that may be above you acting as potential triggers.  Another concept to realize is runout paths criss-cross in both Ravines so you may think you are away from the worst hazard only to be within the track and runout of a different gully or slope.  All of today’s hazards and factors will be difficult to mitigate and manage if entering avalanche terrain.  It is truly a head’s up day with obvious clues from mother nature that she’s thinking about avalanches!

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.Posted 8:463a.m. 3-16-2013. 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

2013-03-16 Print Version