Avalanche Advisory for Saturday, April 8, 2017

This advisory expires at Midnight.

Huntington and Tuckerman Ravines 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. The only exception is the Little Headwall which has Low avalanche danger. Natural and human-triggered avalanches are unlikely. Open water and thin snowbridges exist in spots.

AVALANCHE PROBLEM: Wind shifted to the west-northwest as mixed precipitation transitioned to snow late yesterday afternoon. The 4-5” of new snow which fell overnight on strong winds, combined with 2-4” more snow today will make human-triggered wind slab avalanches likely throughout our forecast area. Natural avalanches are also possible and can run the full length of our well-developed slide paths. An avalanche occurring today in the Lip or Center Bowl area in Tuckerman Ravine could run into the buried trees and shrubs which mark the entrance to the floor of the Ravine. Smaller avalanches in cross loaded slopes will also be problem.  Low visibility, new snow and continued wind-loading are all the redflags you should need to develop your travel plans this morning. Today is a good day to go to the rock gym or perhaps take a windy, low visibility hike to the summit. Winter is holding on for another day.

WEATHER: Winds from the northwest began to rage around midnight last night and have blown steadily from the WNW in the 60’s mph since then. The summit also recorded .5” of water equivalent snow overnight. This played out as four to five inches of snow at Hermit Lake with the same amount likely falling in the alpine. Two to four inches more snow will fall today accompanied by the same wind direction and velocity. Forecast wind from the northwest at 55-75mph is an ideal speed for continued loading of our forecast areas. Anticipate summit temperatures in the mid-teens F on the summit, 20ish F in the Ravines with strong winds through the day.

SNOWPACK: Wet snow from earlier in the week went through a strong heating cycle as temperatures warmed and .7” of rain fell yesterday. Older ice crusts deeper in the snowpack survived this thaw though the soft surface snow released widespread loose wet sluffs and rollerballs. The Lower Snowfields and other areas beneath buttresses and ice flows look as if a giant spilled a huge barrel of softballs. All of this surface snow is refrozen into a crust which is likely bootable in some spots but pencil hard and requiring crampons in others. New wind slabs will easily slide at or just above this icy layer today. The John Sherburne ski trail still has plenty of coverage despite the recent rain and warm temperatures. You’ll find 4-5” inches of new snow diminishing to a trace or an inch at Pinkham Notch along with 70 or so racers making their way down the trail during the annual Tuckerman Inferno Pentathalon. This fundraiser, hosted by the Friends of Tuckerman Ravine, helps to support facilities, trails and the missions of this avalanche center. Thanks, FoTR!

The Harvard Cabin is closed for the season. We will continue posting advisories there as long as it is logistically feasible or until the ice melts out. Be sure to check the date of the advisory when you read it!

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 caretaker at Hermit Lake Shelters.

Posted  7:25 a.m., Saturday, April 8, 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

2017-04-08