Avalanche Advisory for February 23, 2017

This advisory expires at Midnight.

Huntington Ravine and Tuckerman Ravine have LOW avalanche danger. Natural and human-triggered avalanches are unlikely.

 AVALANCHE PROBLEM: Skier triggered wet-loose avalanches will be the primary avalanche problem today though other emerging spring hazards will pose an equal or greater danger. Loose but heavy sluffs of snow kicked up by a skier can be challenging to deal with at times so be mindful of this hazard, especially if venturing into areas with a sunny aspect or a previously unskied area. Several warm days have allowed our snow to adapt to the heating through settlement of the layers of snow, making a deeper wet slab avalanche only a very remote possibility.

WEATHER: Summit temperatures have remained above freezing for the past 24 hours with our forecast areas above freezing for a couple of days now. In the past six hours the temperature has been 34F on the summit with the mercury at 41 currently (at 7:30am) at Hermit Lake. A warm front developing over the region will allow southwest flow to continue today. The degree to which temperatures will rise is a little uncertain due to cloud cover and limited mixing in the atmosphere. Add to this a deep and cold snowpack and calm winds allowing for cold air to settle through the valleys, and you have a recipe for a jambalaya of surface conditions. Suffice it to say that early spring conditions will be on tap even with the forecasted cloud cover. Expect W winds at 30-45 mph increasing to 65-85 mph later. Temperatures on the summit will reach the upper 30’s with even warmer temperatures in the Ravines.

SNOWPACK: Postholing in one gully with firm conditions in another will make it a smart idea to have a flexible itinerary. Snow temperature 20 cm down is -1.5C at Hermit Lake so anticipate firm surface conditions in areas of firm old wind slab on shady aspect. Softer snow and sunny aspects will likely allow much deeper boot penetration outside of existing bootpacked trails. A harvest of corn is likely on most aspects. The warm temperatures have begun to open glide cracks so beware of moats near rocks and opening cracks mid-slope. Due to the generally warm winter conditions, streams have remained mostly unfrozen so punching through into water may be possible in thinly bridged areas. Spontaneous rock and ice fall are also possible today as ice loosens its grip and becomes plastic. While probably not a large or widespread problem yet, be choosy as to when hanging out or taking your helmet off will be a good idea.

Seven days ago, there was 94” of snow at the Hermit Lake snowplot with 81” this morning. Things are changing rapidly here.

A week from today,  March 2nd at 6:30pm, Allspeed Cyclery and Snow will be hosting a shindig at the Portland store to benefit Friends of Tuckerman Ravine and the avalanche center. A brief presentation from our forecast team as well as raffles and prizes should make for a fun and educational night. Information and tickets available online at http://www.friendsoftuckermanravine.org/allspeed_party with more information available through Allspeed’s Facebook page.

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  8:15 a.m., Thursday, February 22, 2017. A new advisory will be issued tomorrow.

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

2017-02-23