This advisory expires at Midnight.
All forecast areas of Huntington and Tuckerman Ravine have LOW avalanche danger. Natural and human-triggered avalanches are unlikely. Watch for unstable snow on isolated terrain features. Generally safe avalanche conditions exist
AVALANCHE PROBLEM: Current weather has removed the threat of wet avalanches. Saturated snow from warm and freezing rain will be subjected to cold temperatures today and turn to an impenetrable snowpack. This will create a slick sliding surface that will necessitate the use of crampons and an ice axe for safe travel. With up to 2” of snow possible this afternoon on rapidly increasing NW winds, wind slab may develop in areas. This will likely be isolated behind terrain features due to strong wind and a hard snow surface.
WEATHER: Between Sunday evening and Tuesday night, the Summit recorded 0.51” of water as various forms of mixed precipitation. This same period also saw a maximum temperature of 36F and a minimum of 23F, with only a three-hour window below 28F. Early this morning, cooling began with a current temperature of 18F on the Summit and 22F at Hermit Lake. By tonight, the thermometer will likely be in the single digits in areas. Winds will remain from the NW and increase through the day, possibly breaking the century mark. Snow showers may develop in the afternoon, bringing up to 2” today and another 1” tonight.
SNOWPACK: After a two days of warmth, colder conditions are returning to the mountains. Just over half an inch of water fell in various forms of mixed precipitation on Monday and Tuesday. Combined with the above freezing temperatures, all surfaces became saturated. As the cold freezes this wet snow, the snowpack will lock up. High wind speeds will help drive the freezing process, but in areas that have not seen much recent traffic or have vegetation hidden just under the surface, expect postholing to be an issue for the early part of the day. Areas that have more exposed old surface will freeze quicker and will be prime surfaces for long, sliding falls. Snow forecast for the afternoon will be subjected to strong wind and have trouble sticking to the hard snow surface. If traveling later in the day, pockets of wind slab may develop, but these will likely be driven far down the terrain and be tucked in behind terrain features.
• 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., Wednesday, March 29, 2017. A new advisory will be issued tomorrow.
Helon Hoffer, Snow Ranger
USDA Forest Service
White Mountain National Forest
(603) 466-2713 TTY (603) 466-2856