Avalanche Advisory for Superbowl Sunday 2-5-2012

Tuckerman Ravine has both LOW and MODERATE avalanche danger.  The Lobster Claw, Left Gully, and Hillman’s Highway have Low avalanche danger.  Natural and human triggered avalanches are unlikely except in isolated terrain features.  All other forecast areas in Tuckerman have Moderate avalanche danger.  Natural avalanches are unlikely and human triggered avalanches are possible.  Heightened avalanche conditions exist on specific terrain features.  Evaluate snow carefully to identify these areas of concern.  The Lower Snowfields and the Little Headwall are not posted due to an overall lack of snow. Forecasts for these locations will begin when conditions warrant.

Huntington Ravine has LOW avalanche danger.  Natural and human triggered avalanches are unlikely except in isolated terrain features.  Expect these pockets to exist and avoid them by staying to older more stable surfaces. 

On this clear beautiful morning you’re probably wondering how is he going to tie in the Superbowl with avalanches?  Well funny you should ask because the issues that developed yesterday, and we are dealing with today, are directly related to the ole gridiron.  Yesterday the summit picked up 1.2” (3cm) of new snow and 1.2” (3cm) in the 48 hours before that totaling 2.4” (6cm) over the past 3 days with strong W and NW winds between 40 and 80 mph (65-129kph).  We remark so often that low snow amounts can make such a remarkable difference in snow stability due to impressive new slabs.  Avalanche textbook editors may conclude we’re nuts when we get into all the issues and conversations related to 1-2” of snow, but the issues are real and that’s where football comes in.  Above Tuckerman and Huntington Ravines is a large plateau below the summit cone consisting of Bigelow Lawn and the Alpine Garden.  These large expanses are the initial snow collection fields before our dominate W/NW winds plow it all into the basins below.  Bigelow lawn being about a mile square is equivalent to about 590 football fields (1.1 acres each) side by side not including end zones.  Now picture a row of big bucket loaders plowing 2” off all these fields into the Ravine catch basins below.  You’ve seen a small version of this when you go to Walmart and see the mountains of snow at the far end of the lot after a dusting.  Now you’ve got the concept!

We were impressed yesterday how much the Ravine changed yet again due to the aforementioned concept.  Right Gully, the upper Sluice, The Lip are all good examples of larger growth from this last 3 days of loading.  Some folks found themselves in mid-thigh low density slabs in some lee areas.  Through yesterday and overnight strong wind velocities moved a lot of this low density snow out of the Ravines or down low into protected locations on approaches.  This has left behind widespread wind effect in Hillman’s, Left Gully, and most of Huntington. There are some some sizeable locations of leftover slab, hence the Moderate rating for most of Tuckerman and the concern for isolated pockets of instability in Huntington. Snowfields in Tuckerman’s Center Bowl and Lip are getting bigger as rock and water ice continue to get buried with each snowfall or loading event.  Larger snowfields without anchors and delineators such as cliffs and ice are generally easier to trigger than smaller slopes given the same consistent weak layer.  Although it’s getting rather late into the winter more of our forecast areas are moving towards average, which will in turn begin increasing our concern for more frequent avalanche activity.  But as for today, expect the usual spatial variability on Mount Washington with hard stable surfaces interjected with new snow instabilities in strong lee locations that were protected from wind scouring.  If you’re flexible on where you go today you will have a number of options to remain in stable terrain.  However if you insist on traveling through new soft slabs without constant stability evaluations you may possibly avalanche a slope in “Moderate” forecasted terrain and some isolated pockets in areas at “Low”.  Some light snow showers are expected late in the day along with a lowering cloud deck.  This should not affect today’s stability, but be sure to check tomorrow’s advisory before entering avalanche terrain for any issues that developed overnight.     

  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 8:20am. 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

2012-02-05 Print Friendly