Avalanche Advisory for Tuesday, February 14, 2017

This advisory expires at Midnight.

Huntington Ravine has MODERATE avalanche danger today. All forecast areas have Moderate avalanche danger. Natural avalanches are unlikely and human-triggered avalanches are possible. Heightened avalanche conditions exist on specific terrain features. Evaluate snow and terrain carefully to identify features of concern.

Tuckerman Ravine has CONSIDERABLE and MODERATE avalanche danger today. Sluice, Lip, Center Bowl and Chute have Considerable avalanche danger. Natural avalanches are possible and human triggered avalanches are likely. Dangerous avalanche conditions exist. Careful snowpack evaluation, cautious route-finding and conservative decision-making are essential. Lobster Claw, Right Gully, Left Gully, Hillman’s Highway and Lower Snowfields have Moderate avalanche danger. Natural avalanches are unlikely and human-triggered avalanches are possible. Heightened avalanche conditions exist on specific terrain features. Evaluate snow and terrain carefully to identify features of concern. Little Headwall has Low avalanche danger. Natural and human triggered avalanches are unlikely. Watch for unstable snow on isolated terrain features.

AVALANCHE PROBLEM: Wind and a barrage of snow over the past 36 hours formed Wind Slab in our terrain. The weather today will not increase the avalanche danger. The area of greatest concern today will be the Sluice through Chute in Tuckerman. A fresh crown in the Lip is a sign that this area is on the edge of shedding its most recent layer of wind slab and may be reactive to a human-trigger. All other forecast areas are displaying sign of avalanche debris with few crown lines visible. This should highlight the reloading that has taken place with several avalanche cycles occurring yesterday. It should also be noted that we are seeing signs indicating the largest avalanches of the season took place yesterday. With Hillman’s having jumped the dogleg and Huntington gullies running into the trees, avalanche paths are fully developed and now contain significant amounts of snow.

WEATHER: The storm yesterday did not disappoint. Since Sunday morning, the Summit recorded just shy of 24” of snow with a SWE of 1.96”. Winds started from the S and then shifted to the ESE gusting to 60mph Sunday evening. On Monday, winds swung to the N and NW, gusting to 80mph midday before calming overnight to a current N 22mph. Today will be sunny and clear to start with clouds developing through the day. Wind speeds will remain low and shift to the W. Tonight, winds will increase to 40mph and shift to the S with a chance of up to 2” of snow late.

SNOWPACK: Prior to Sunday, our surface was a one-inch thick breakable crust from Wednesday as well as firm wind slab formed on Friday. An avalanche cycle on Friday ripped up the breakable crust in the Center Bowl, proving snow had the potential to step down below this crust layer. Snow over the past two days was relatively light density (~8%) and moved around by winds that changed direction and blew strong for periods of time, forming wind slab in most areas. There is clear evidence of scouring at high elevations in both Ravines. Huntington is showing more signs of wind-affected snow than Tuckerman with the Fan and the approaches to ice climbs having the most well-developed wind slab. In Tuckerman, more widespread smooth surface at mid-elevations along with a fresh crown in the Lip points to much more wind loading and wind slab that could be reactive.

 

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  8:30 a.m., Tuesday, February 14, 2017. A new advisory will be issued tomorrow.

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

2017-02-14