Avalanche Advisory for Thursday, April 5, 2018

Huntington and Tuckerman Ravine have LOW avalanche danger today. All forecast areas have Low avalanche danger. Generally safe avalanche conditions exist. The Little Headwall is no longer forecast due to a lack of snow.

AVALANCHE PROBLEM: While isolated pockets of wind slab may be hiding under terrain features in the lee of west wind, these will be small, firm, likely stubborn to trigger, and not the real hazard of the day. The refrozen surface of the snowpack will require filing your crampons and ice axe just to gain purchase. Self-arresting today will be next to impossible, making long, sliding falls one of the two main hazards for the day. The other objective hazard that will have to be dealt with from the moment you open your car door in Pinkham Notch will be the wind. Sustained wind speeds around the century mark will take their toll on anyone long before they reach avalanche terrain. For those wishing to go climbing today, be aware of the potential for ice dams as yesterday’s rain was followed by a drop of 47F (from 39F to -8F) over 15 hours.

WEATHER: Yesterday, the summit of Mount Washington recorded 0.32” of rain and freezing rain. Temperatures began the day in the 20sF and peaked at 39F. In the afternoon, precipitation stopped for several hours and cold air came in from the north, allowing the temperature to plummet to a current -6F on the summit and 5F at Hermit Lake. Several hourly observations during the night had snowfall, leading to a trace of snow at Hermit Lake and 0.9” on the summit. Since midnight, winds have been steady from the west at 90mph+ with gusts up to 120mph. Today, the high will reach around 0F with continued summits fog and clouds. Up to an inch of snow may arrive, though the real story for the day will continue to be the wind. Wind speeds will stay elevated for the day with gusts continuing to exceed 100mph.

SNOWPACK: Over the past week, very little new snow has fallen in avalanche terrain. During this time, we have seen two periods of rain followed by a drastic freeze, leaving the surface of the snowpack as a solid refrozen crust. Below this melt/freeze crust, cold dry snow can be found, but you will need a steel shovel to access that snow. The inch of snow that was recorded by the Mount Washington Observatory overnight has been subjected to 100mph winds all night and will continue to see this today. It is likely that most of that snow has been wind transported out of avalanche terrain, though some features in our most extreme terrain may be able to keep a small amount of this snow.

Due to the strong wind, there is at least one blowdown on the Tuckerman Ravine Trail and likely some on the Sherburne. With wind forecast to remain elevated, expect more trees and limbs to come down during the day.

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  8:00 a.m., Thursday, April 5, 2018. A new advisory will be issued tomorrow.

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