Avalanche Advisory for Wednesday, April 18, 2018

Huntington Ravine will have MODERATE and LOW avalanche danger today. Central, Pinnacle, Odell, South and Escape Hatch will have Moderate avalanche danger. Evaluate snow, weather and terrain carefully. Heightened avalanche conditions exist on specific terrain features. Northern gullies in Huntington have Low avalanche danger. Watch for unstable snow on isolated terrain features

Tuckerman Ravine will have MODERATE and LOW avalanche danger today. Sluice, Lip, Center Bowl, Chute, Left and Hillman’s Highway will have Moderate avalanche danger. Evaluate snow, weather and terrain carefully. Heightened avalanche conditions exist on specific terrain features. All other forecast areas will have Low avalanche danger. Watch for unstable snow on isolated terrain features. The Little Headwall and the streambed above has too much open water to be a good route for exiting the Bowl. Hiking down is the recommended option.

Bear tracks have been seen in the vicinity of the Fire Road and the Tuckerman Ravine Trail. Please be careful with your food. Sometimes “a fed bear is a dead bear” when they become habituated to humans and their food waste. Use the bear boxes located at the Hermit Lake Shelters when camping and be sure your snacks make it into your mouth.

AVALANCHE PROBLEM: The amount of snow available for transport by increasing westerly winds is driving the avalanche problem today. Deeper areas of new snow may be attractive for skiing and riding but bear in mind that the new snow may not be well bonded yet to the old refrozen surface. As wind increase today, be on the lookout for wind slabs growing over a foot thick and may fail on softer new snow beneath. Lower angled terrain may have the best skiing since the icy bed surface will be lurking just below the new snow. The potential for wind slab avalanches in many areas is a reminder that it is not springtime in the mountains yet.

WEATHER: In the past 24 hours, three inches of new snow fell on the summit with 3cm (1.18”) of 13% density snow at Hermit Lake. This disparity is primarily due to the elevation of the freeze line while yesterday’s low pressure system dumped copious amounts of rain that turned to wet snow in the afternoon. Currently, this new snow is refrozen into a thick crust from Pinkham to Hermit Lake with limited amounts of loose snow on the ground at mid-elevations with more likely above in the alpine. Upslope snow showers may continue today bringing a trace to two inches of snow. Wind will shift this morning from northwest to west and increase to the 45-60 mph range. Expect low visibility as lingering moisture produces summit fog along with snow showers. Light snow is falling at Hermit Lake this morning. The temperature on the summit is currently 12F and will rise to 20F.

SNOWPACK: Almost 10” of new snow with 3.4” liquid equivalent has fallen on the summit in the past 48 hours. The mixed bag of precipitation in the past 4 days has generally led to an isothermal and stable deeper snowpack. The return to winter weather yesterday and today brings new avalanche concerns in the form of new snow and new wind slabs. Check for bonding of the new snow to the old and look for signs of continued wind loading today. Continue performing stability tests, traveling with a partner and carrying avalanche rescue equipment including a beacon because it is not spring yet!

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.
• Posted  8:05 a.m., Wednesday, April 18, 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

2018-04-18