Avalanche Advisory for Saturday, January 20, 2018

Huntington and Tuckerman Ravines have LOW avalanche danger. Natural and human-triggered avalanches are unlikely in all forecast areas.  Watch for unstable snow on isolated terrain features.  The Little Headwall is mostly open water or frozen waterfall ice.

Due to the open waterfall hole and 20’ crown line, the Tuckerman Ravine Trail is closed in the Ravine between Lunch Rocks and the Alpine Garden Trail. Please use the Winter Lion Head Route if going to the summit from Pinkham. Other routes to the summit from the east side are significant mountaineering routes.

 AVALANCHE PROBLEM: Very widely scattered areas of wind slab may be found in avalanche terrain today though the majority of our forecast area is scoured down to a hard icy crust. This icy surface, combined with strong winds, will present significant travel challenges today. This surface creates the opportunity for long, sliding falls which can end in a pile of rocks, melted holes in stream beds or trees if not arrested immediately. Our snowpack took a beating in last week’s rain storm and what’s left in its wake requires crampons and careful footing in steep terrain. Some snow showers this afternoon will not likely create significant avalanche problems though may challenge visibility a bit and further obscure refrozen footprints and other trip hazards.

 WEATHER: The current temperature on the summit is 23F with a west wind blowing at 82 mph. It is just below freezing at the Hermit Lake with no new snow on the board.  Two tenths of an inch of snow fell on the summit during snow showers early yesterday but otherwise the dry spell and warmup continues this morning.  Early this afternoon, a cold front swings through and drops the mercury to the mid-teens. A bit of mixed precipitation associated with the frontal passage may occur this morning, though the strong winds will be the most notable weather factor today. Anticipate west winds around 80 mph to continue through the day with gusts over 100 mph. Snow showers seem likely this afternoon as a secondary cold front passes with up to an inch falling by dark. The wind will moderate overnight with temperatures in the mid-teens and a decreasing west wind in the 50 mph range tomorrow.

SNOWPACK: At the Hermit Lake snow plot, there is 86 cm of hard, refrozen snow at the stake. A prolonged warming spell with rain late last week turned the upper portion of the snowpack into a knife hardness crust. That warmup ended with a period of freezing rain that glazed trees and snow surfaces at our elevation with ice which created little bonding opportunities for the several inches of snow which has fallen since. Most of that snow has been scoured out of our avalanche terrain and redeposited at lower elevations or in a few scattered and sheltered pockets. What didn’t blow out of the terrain already will be scoured out today as winds reach 100 mph. The blown out portion of the Lip below the Tuckerman Ravine Trail and the hard, refrozen debris pile remain visible in Tucks. Overall, surface conditions are hard and icy, making crampons, an ice axe and careful movement in steep terrain necessary.

Please Remember:
• Safe travel in avalanche terrain requires training and experience. This bulletin 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 Harvard Cabin.
• Posted 8:15 a.m., Saturday, January 20, 2018. A new advisory will be issued tomorrow.

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

2018-1-20