This advisory expires at Midnight.
Tuckerman Ravine has CONSIDERABLE and MODERATE avalanche danger. Sluice, Lip, Center Bowl, Chute, Left Gully and Hillman’s Highway have Considerable avalanche danger. Natural avalanches are possible and human-triggered avalanches are likely. Lobster Claw, Right Gully and Lower Snowfields have Moderate avalanche danger. Natural avalanches are unlikely and human-triggered avalanches are possible.
Huntington Ravine has CONSIDERABLE and MODERATE avalanche danger. Central, Pinnacle, Odell, South and Escape Hatch have Considerable avalanche danger. Natural avalanches are possible and human-triggered avalanches are likely. North, Damnation and Yale have Moderate avalanche danger. Natural avalanches are unlikely and human-triggered avalanches are possible.
AVALANCHE PROBLEM: Natural wind slab avalanches are possible in both Ravines today. High winds and continuous snowfall for the past 2 days has built fairly thick wind slabs. History has shown that these wind slabs will exist in middle start zones such as beneath the ice in the Center Bowl, around the fork of Hillmans and on the approaches and middle pitches of climbs in Huntington. Strong westerly winds tend to scour northern gullies in Huntington Ravine. Natural avalanches are less likely in Lobster Claw and Right Gully but smaller and still dangerous human-triggered avalanches could occur there.
WEATHER: It is truly a different world up here compared to the surrounding valleys due to intense upslope snowfall from lingering moisture. Snow has been continuous for over 48 hours with high winds and drifting snow and making accurate measurements challenging. The sheltered snow study plot near Hermit Lake was wind effected again this morning with only 6 cm recorded, and 8.9cm recorded from midnight to 6am on the summit. Looking around, it is pretty obvious that lots of snow has fallen, probably more than has been recorded, with grinning skiers reporting great runs on local ski trails. Expect heavy drifting and scouring above tree line today. Low visibility and cold temperatures in the single digits F will make patient observation and decision making in avalanche terrain challenging. West winds 65-85 mph will relax through the day diminishing to 50-70 mph by nightfall.
SNOWPACK: Strong winds and snow fall yesterday limited field time due to the risk of natural avalanches. Suffice it to say that signs of wind loading were obvious and occurred all day. Snow squalls were observed last night as well. Hourly observations from the summit show wind speeds in the 70-90 mph range for the past 36 hours or so. Expect weaker layers to exist near the refrozen, rimed crust from Tuesday/Wednesday’s sleet and rain event as well as within the new snow from wind speed and snow particle changes included rimed snow crystals. The strong recent winds have most likely made stubborn wind slabs with more sensitive wind slabs in strongly sheltered areas. Safe travel in avalanche terrain while successfully navigating avalanche paths will be challenging today, at best.
The Lion Head Winter Route is open and the most direct route to the summit from the east. Please be careful of bridge construction debris near crossover 7 on the Sherburne Trail when skiing or riding. The recent dense “snow” has resulted in good coverage on the Sherburne which will be a good and relatively wind sheltered place to enjoy the new snow falling today.
- 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 8:00a.m., Saturday, January 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) 466-2713