Avalanche Advisory for Saturday March 22, 2014

Tuckerman Ravine will have HIGH and CONSIDERABLE avalanche danger later today. The Lip, Center Bowl, and Chute will have High avalanche danger. Natural avalanches are likely and human triggered avalanches are very likely. Travel in these areas and their runout zones is not recommended. Lobster Claw, Right Gully, Sluice, Left Gully, Hillman’s Highway, and the Lower Snowfields have Considerable avalanche danger. Natural avalanches are possible and human triggered avalanches are likely in these locations. Dangerous avalanche conditions exist; careful snowpack evaluation, cautious route finding, and conservative decision making are essential. The Little Headwall has Moderate avalanche danger. Natural avalanches are unlikely and  human triggered avalanches are possible.

Huntington Ravine has CONSIDERABLE avalanche danger. Natural avalanches are possible and human triggered avalanches are likely in these locations. Dangerous avalanche conditions exist; careful snowpack evaluation, cautious route finding, and conservative decision making are essential.

AVALANCHE PROBLEM: Wind Slabs deposited yesterday are currently the primary avalanche problem this morning and will become the secondary issue this afternoon.  Storm Slabs and new Wind Slabs will couple to be the 2 main problems this afternoon as steady snow and high winds create significant new loading.  This afternoon combination, causing natural avalanche potential, will stress the already swollen slabs that exist currently.  It is a very heads up day! Avalanche activity that occurs late today from our most sizable snowfields, from the Lip south to the Chute, could step down to deeper slabs and be large.

WEATHER:  Moderate winds this morning from the WSW will shift to the WNW through the afternoon and increase from 40 to 90mph (64-144kph) by around dark.  As this ramp up occurs snowfall will increase with 3-6+” (7.5-15cm) possible between noon and 8pm. Temperatures will be cold as the mecury slides downward from the teens to below zeroF.

SNOWPACK:  Again, it is very important to pay attention to mother nature by watching exactly how weather plays out today. We have a classic sucker hole scenario setting up with pretty beneign weather conditions this morning, although with very respectable avalanche conditions.  I would call many areas solidly in Moderate and towards the upper end of the rating in places this morning.  This will change with the incoming weather event which will cause natural avalanches to be possible or likely, depending on location, later this afternoon.  If we do end up with snowfall at the lower end of the forecasted range, areas posted at High will be unlikely to get there.  However, even with 3″, all areas will at least reach Considerable due to winds moving from 50-80mph during the majority of daylight this afternoon.  Saying this, all weather indications are pointing at exceeding this lower accumulation range, so expecting dangerous to very dangerous avalanche late this afternoon would be a smart baseline.

Yesterday, high winds moved snow available in the alpine zone, and 2.5″ of new snowfall, in the Ravines.  Dodge’s Drop ran big and we would expect the Center Bowl of Tuckerman to have gone pretty large as well, but it is devoid of fracture lines this morning.  This tells me it likely went early and then reloaded, covering crowns.  Therefore, these large snowfields have fairly new slabs that are about 24 hours young, which in turn harbors new instabilites.  I feel confident of this mostly due to knowing the history of weather. Cold air on Friday, high winds, and new snowfall dominated by heavy riming/graupel undoubtedly have set up instabilities, but these conditions kept us from the field yesterday.  These slabs will be loaded with new weight today by snowfall that will come in on a moderate wind initiating as a soft slab. As winds increase slabs will become more dense, giving avalanche terrain an unstable upsidedown snowpack.  This early soft slab today will be the most likely weakness that will fail with the harder slab above that develops this afternoon, plausibily stepping down into the Friday slabs.  So as the day goes on, more and more redflags and alarm bells should be going off in your head! 

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 Visitor Center, or the caretakers at Hermit Lake Shelters and Harvard Cabin.
  • Posted 10:09 a.m. 03-22-2014. A new advisory will be issued tomorrow.

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

2014-03-22 print