Avalanche Advisory for Thursday, December 28, 2017

This advisory expires at Midnight.

Huntington and Tuckerman Ravine have MODERATE avalanche danger. Natural avalanches are unlikely and human-triggered avalanches are possible in all forecast areas. Evaluate snow and terrain carefully. Lower Snowfields and Little Headwall in Tuckerman have Low avalanche danger due to lack of a developed snowpack. Watch for unstable snow on isolated terrain features such as Dead End and Duchess above the Lower Snowfields.

 AVALANCHE PROBLEM: High winds overnight continued to transport snow into our forecast area. Sustained NW wind in the 80s and 90s mph worked over the snow last night. These wind speeds have a history of scouring the northern gullies in Huntington and packing dense and stubborn wind slabs in other areas of both Ravines. Unfortunately, limited visibility this morning gives us no opportunity to confirm. Many areas like the northern gullies in Huntington and many forecast zones in Tuckerman are probably closer to a Low rating due to the density and stubbornness of wind slabs. If you chose to travel into the terrain today, be on the lookout for these dense slabs which may have formed over a weaker layer of storm snow.

 WEATHER: Very cold temperatures will make for challenging conditions today. Harvard Cabin temperature is currently -13F with a low reached last night of -17F. Summit temps have rebounded to -31 F from an overnight low of -33 F. Wind speeds are currently in the mid-80’s mph from the NW. Wind should relax to the 35-50 mph range this afternoon reaching mid 40’s mph by sundown. Anticipate the mercury climbing slowly towards -10 F or so on the summit in the afternoon.

SNOWPACK: The summit recorded no new snow yesterday though a brief visit to Tucks yesterday confirmed that moderate wind transport of snow on the ground continued. For those who haven’t been keeping track, the summit has recorded 80” of snowfall this month. Currently there is 76cm on the ground at the Harvard Cabin snow plot. If you are inclined to multiple winter sports, the pendulum seems to be swinging from skiing and riding and back towards mountaineering and ice climbing, though soft snow can probably still be ferreted out in the trees.

 The Lion Head Winter Route is open and the preferred route to the summit from the east side. The John Sherburne ski trail has good coverage with limited areas scoured down to the icy base. There are still a few rocks just submerged in the snow so easy turns are advisable.

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 7:35 a.m., Thursday, December 28, 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

2017-12-28