Avalanche Advisory for Saturday, February 18, 2017

This advisory expires at Midnight.

Huntington Ravine has MODERATE and LOW avalanche danger today. Central Gully has Moderate avalanche danger. Natural avalanches are unlikely and human-triggered avalanches are possible. All other forecast areas in Huntington Ravine have Low avalanche danger. Natural and human-triggered avalanches are unlikely. Watch for unstable snow on isolated terrain features.

Tuckerman Ravine has MODERATE and LOW avalanche danger today. Sluice, Lip, Center Bowl, and Chute 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, Lower Snowfields and Little Headwall have Low avalanche danger. Natural and human-triggered avalanches are unlikely. Watch for unstable snow on isolated terrain features. 

AVALANCHE PROBLEM: Wind slabs that developed over the past 48 hours will be the primary stability concern today. These will be firm and stubborn in most areas.  Beware of smooth areas of wind slab in the steepest areas or in any convex area you might find. Though these wind slabs will be tough to trigger, it is not too much of a reach to imagine someone finding the right thin spot in steep terrain. While an active avalanche cycle ripped out the soft weak failure layer in most of our larger forecast areas, most slopes have not yet been tested by climbers or skiers so don’t forget to dig and poke around when entering the terrain.

WEATHER: It is currently 26F at Hermit Lake with calm winds and overcast skies. A warm front pushing through this morning will allow skies to clear and temperatures to warm later today to a balmy lower 30’s F. Partly cloudy conditions may even allow some sunshine to warm things further. Winds will increase through the day and reduce any concerns for the incoming sunshine to warm and weaken the snowpack. A cold front will approach rapidly late this afternoon and change things dramatically. Wind will increase to 65-85mph with gusts to 100 mph by evening. It’s a good day to have a strong headlamp and clear goggles just in case.

 

SNOWPACK: Northwest winds yesterday continued to erode surface snow. Heavily textured (sastrugi) snow and avalanche debris share the stage with smooth areas of firm but edgeable slab. More wind sheltered terrain like Lobster Claw and Right Gully are mostly smooth but don’t share the terrain factors that nudge areas like the Sluice and Lip into a higher danger rating. Hillmans and Left Gully have the usual mix of surfaces from wall to wall making it possible to choose your travel surface. Areas of ice crust from the most recent sleet event are even exposed in a few locations due to wind scouring. In other areas of Tuckerman, the ice crust was ripped up by avalanche activity.

It’s the start of President’s Day weekend. With so many people around, please be respectful of people below you and be on the lookout for hazards overhead.

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  8:10 a.m., Saturday, February 18, 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