Avalanche Advisory for Saturday, February 3, 2018

Huntington Ravine has MODERATE and LOW avalanche danger. Central Gully has Moderate avalanche danger. Heightened avalanche conditions exist. All other forecast areas have Low avalanche danger. Watch for unstable snow on isolated terrain features.

Tuckerman Ravine has MODERATE and LOW avalanche danger. Sluice, Lip, Center Bowl, Chute and Left Gully have Moderate avalanche danger. Evaluate snow and terrain carefully. Lobster Claw, Right Gully, Hillman Highway and Lower Snowfields have Low avalanche danger. Watch for unstable snow on isolated terrain features. The Little Headwall has not refilled with snow. The void left in The Lip from the wet avalanche is slowly filling in but still has a significant crown face above what is now a nasty terrain trap. Neither of these features are visible from above. 

AVALANCHE PROBLEM: Wind slab is the primary avalanche problem today. Moderate rated areas have more areas of wind slab to contend with and fewer opportunities to avoid the potential instabilities. Staying on the old, icy surface is a safer bet for avoiding these wind slabs. Due to high wind velocities yesterday, these slabs are likely to be firm but may not be well bonded to deeper layers. Remnants of older wind slabs are beneath these new wind slabs in some areas, particularly in areas rated moderate, and may also harbor a weak layer. Don’t be complacent when approaching these slabs which may appear stable but can still be triggered if you happen to step on a thin spot in the slab.

WEATHER: Fog continues to cling to the higher summits and both Ravines though skies are clear overhead. The temperature is currently -11F at Hermit Lake and -24F on the summit with a west wind at 70 mph gusting to 80 mph. Look for temperatures to warm slowly through the day reaching -4F on the summit by nightfall. The west wind will subside through the morning but remain a brisk 35-50 mph this afternoon. Wind will begin to increase again and shift southwest as a low pressure system approaches overnight. Temperatures will continue to warm through tomorrow but remain plenty cold for the approach system to bring a significant snowfall rather than another round of rain.

SNOWPACK: Thursday and Friday brought about 6” of fresh low density snow to the summit. Raging winds during that period scoured much of it off of our icy, hard snowpack while building firm wind slabs in the most sheltered areas. Field observations low in Hillman’s Highway yesterday and Huntington this morning confirm that the light density snow had a hard time sticking to the old surface in most places. Though our wind slab problem is not widely distributed through the terrain, the icy surface beneath makes for nasty consequences in the event of a fall or avalanche. Move carefully in the terrain.

The Sherburne Trail improved though the recent snow was primarily upslope driven so less of it fell on the Sherburne. Conditions are still icy with rocks and rain damage still a problem.

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 Harvard Cabin.
• Posted 8:00 a.m., Saturday, February 3, 2018. 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

2018-2-3