Avalanche Advisory for Monday, March 23, 2015

This advisory expires tonight at 12:00 midnight.

Tuckerman Ravine has MODERATE and LOW avalanche danger. Sluice, Lip, Center Bowl, Chute, and Little Headwall have Moderate avalanche danger. Natural avalanches are unlikely and human-triggered avalanches are possible. Evaluate snow and terrain carefully. Lobster Claw, Right Gully, Left Gully, Hillman’s Highway, and the Lower Snowfields have Low avalanche danger. Natural and human-triggered avalanches are unlikely. Watch for unstable snow on isolated terrain features.

All forecast areas in Huntington Ravine have LOW avalanche danger. Natural avalanches and human-triggered avalanches are unlikely. Watch for unstable snow on isolated terrain features.

 AVALANCHE PROBLEM:  It is no surprise that Wind Slab is the primary threat today. Hard and stubborn slabs of wind packed snow exist in Sluice, Lip and Center Bowl and probably on the approach to Yale and Diagonal and around areas near the Fan. More sensitive slabs likely exist in the most sheltered lee areas near terrain features and steep bushy areas that create natural wind drift fences. Thin, weak spots in firm slabs like we have now can serve as trigger points in an otherwise strong slab so use caution even in Low rated areas. Due to its low elevation and wind sheltered location, the Little Headwall has collected a lot of snow recently which has buried all the anchors and created a convex surface. Be careful if you are among the first few parties to ski the slope; the terrain traps below are nasty.

 WEATHER:  Again, the wind is raging on the mountain with a peak wind speed of 111 mph (179 km/h) recorded yesterday. Currently, NW winds are blowing at 88 mph (142 km/h) with the mercury standing at -22F (-30C). Temperatures will rise to near 0F (-18C) today as winds decrease to the 45-60 mph (70-95 km/h) range. Expect continued gusty conditions peaking at 105 mph (169 km/h) this morning as well as a challenging experience packing up in the parking lot at Pinkham, not to mention standing and walking above treeline. Conditions should moderate this afternoon but January-like weather will persist over the next couple of days. A warm front on Wednesday could bring a mixed bag of precipitation to the forecast area, the nature of which depends on the exact track of the front.

SNOWPACK: Wind speeds like we are having now created a long, sliding fall problem in addition to the avalanche concerns mentioned above. Though the pencil hard slabs on the surface will allow purchase from a hard boot or ski edge, most people would be comforted by the security of crampons. Persistent slabs are a distant threat on the horizon that may become more relevant this week as temperatures warm and the threat of rain increases. Though not a standout danger due to the strength of overlying slabs and their discontinuous nature, these weak layers of faceted snow are certainly present beneath old layers of wind slab.  In our forecast area, you will most likely find these layers near edges of avalanches paths that have not been swept out by previous avalanche activity or really deep in the snowpack. Other terrain around the White Mountains could also contain these weak layers near old buried crusts so you may want to look for this potentially problematic layer deeper than you would dig for a hand shear. A meter deep pit once in a while could help you make informed decisions and keep your risk acceptance discussions real.

 This last weekend saw an uptick in traffic in both Ravines. As we move into the spring season please remember that the party like atmosphere seems to distract folks from the hard of facts of mountain travel. Legitimate mountain hazards are abundant on, above and beneath our slopes and gullies so prepare carefully, stay alert and help others when you can.

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 8:25 a.m. Monday, March 23, 2015. A new advisory will be issued tomorrow.

Frank Carus, Snow Ranger
USDA Forest Service
White Mountain National Forest
(603) 466-2713 TTY (603) 466-2713

2015-03-23 print friendly