Avalanche Advisory for Thursday, March 30, 2017

Huntington Ravine and Tuckerman Ravine have LOW avalanche danger. Natural and human-triggered avalanches are unlikely. Watch for unstable snow on isolated terrain features.
AVALANCHE PROBLEM: The wind slab avalanche problem today will present less hazard management problems than the hard, icy refrozen rain crust beneath. Rain on Monday and Tuesday followed by nearly 24 hours of summit temperatures near 40F were accompanied by snow eating fog. Temperatures dropped to single digits yesterday and last night as snow showers deposited around 2” of new snow in our forecast areas. These cold temperatures combined with the scant amount of new snow on N and NW winds in 50-60 mph range created a nasty dust on crust. The bed surface is rock hard and icy with plentiful options for skirting any pockets of new and potentially unstable wind slab. Small avalanches could be triggered on isolated areas today.
WEATHER: High temperatures on the summit forecast to reach the mid-teen’s F and diminishing winds will make for a fine but wintry feeling day. Plenty of sunshine and good visibility accompany the passage of a high pressure ridge but don’t expect enough warming to soften snow surfaces much, if at all. The current temperature at Hermit Lake is 19F with light wind, summit is 8F with a northwest wind at 40 mph. The big news on the weather horizon is the approaching snow storm that appears to be on track to bring up to a foot of snow to the summit overnight Friday and into Saturday. Be sure to check the avalanche advisory and weather forecast before committing to a trip in the mountains this weekend. Fresh snow followed by nice weather on a weekend is a classic setup for humans having run-ins with avalanches.
SNOWPACK: Rain and warm temperatures have reduced stability concerns for today, as well as for tomorrow’s storm, to new snow and new wind slabs. Widespread icy surface exists through the terrain and is easily visible by its darker gray color. Microspikes on lower angled terrain are the order of the day, along with crampons and ice axe accompanying a strong motivation to not fall on steeper slopes. The Sherburne Ski Trail is an icy junk show and the Little Headwall has running water again, though should be passable after tomorrow’s snow. All in all, the rain and warm weather early this week set us up again for a corn cycle that will be put on hold for a while longer. The next weather system will refresh our already copious amount of snow and bring with it stability concerns for the first weekend in April.


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 8:20 a.m., Thursday, March 30, 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