Avalanche Advisory for Wednesday, March 28, 2018

Huntington and Tuckerman Ravines have LOW avalanche danger. All forecast areas have Low avalanche danger. Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.

 AVALANCHE PROBLEM: Snow on sun exposed slopes yesterday saw at least some degree of softening, which was followed by a quick refreeze in the afternoon. Areas seeing less direct sun continued to hold dry snow. Avalanche concerns are limited to small loose dry sluffs in this dry snow and loose wet sluffs when the refrozen snow warms again. The snowpack is exhibiting good stability and the current wintry mix of precipitation will not significantly change this. That said, we’re still far from a spring snowpack and it remains wise to travel one at a time in avalanche terrain while carrying a beacon, probe, and shovel.

 Spring hazards are becoming prominent and should be considered in your terrain decisions. Long sliding falls on the hard snow, which essentially all steep terrain holds, is a key concern today. If you brave the weather to travel in the alpine, crampons and an ice axe will be crucial equipment. Ice climbers should be aware of potential for ice dams in many climbs which can rupture with the placement of a tool, crampon, or screw. Recent above freezing temperatures has resulted in water flowing beneath ice and can create this hazard.

 WEATHER: A sunny and above freezing day yesterday gave way to increasing clouds which ultimately brought a wintry mix of precipitation to the mountain. Under an inch of mixed precipitation fell overnight and precipitation has tapered off this morning. Summit temperatures will hover around freezing as NW wind blows around 20 mph. Cloud cover should decrease to partly cloudy conditions by late today before increasing again by late tomorrow, bringing another round of precipitation that is currently forecast to fall as rain on the higher summits.

SNOWPACK: The nor’easters of two weeks ago ultimately built a firm upper snowpack which has exhibited good stability. Warming over the last two days did not penetrate deeply into this firm snow, though did allow softening yesterday to allow 4-6” of boot penetration on areas seeing greatest solar heating. These areas refroze quickly. Terrain which remained shaded or saw less direct sun continued to hold dry, cold, and firm snow. The mix of snow and sleet which fell overnight totaled less than a half inch at Hermit Lake. It has likely created additional variability in our snow surface but is not posing a stability concern. Avalanches are unlikely in the current conditions but the limited freeze-thaw action in recent weeks means that we still have a winter-like snowpack structure. The transition to an isothermal spring snowpack will likely occur in the coming weeks and is a time to begin planning for a variety of mountain hazards.

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The Harvard Cabin will be open all nights this week.

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., Wednesday, March 27, 2018. A new advisory will be issued tomorrow.

Ryan Matz, Snow Ranger
USDA Forest Service
White Mountain National Forest
(603) 466-2713 TTY (603) 466-2858