Avalanche Advisory for Sunday, March 25, 2018

Huntington Ravine will have MODERATE and LOW avalanche danger today. Central Gully will have Moderate avalanche danger. Heightened avalanche conditions exist on specific terrain features; identify those of concern. All other forecast areas 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, and Center Bowl will have Moderate avalanche danger. All other forecast areas will have Low avalanche danger. Watch for unstable snow on isolated terrain features.

AVALANCHE PROBLEM: Snow that arrived overnight has the potential to form wind slab and dry-loose avalanches. Another shot of snow this morning will exacerbate this problem. While wind speeds should remain mild by our standards, the recorded snow has a very light density, making wind transport possible on low wind speed. Wind speeds should increase slightly this morning to above 40mph. This has the potential to load snow into the northern gullies in both ravines as well as cross-load Moderate rated terrain. With the combination of snow density and wind speeds, expect wind slab to be touchy to a human trigger, particularly with the firm bed surface it will reside on. While northern gullies in Huntington are more in the direct lee of today’s wind, a smaller fetch and confined, steep terrain will make dry-loose sluffing more of a an issue. If an avalanche occurs, it is likely to be small, but potentially enough to swipe your feet out from underneath you and lead to a long, sliding fall. As the bed surface in all avalanche terrain is firm, arresting a fall today will be difficult.

WEATHER: Afternoon and overnight snow showers capped off a largely bluebird day yesterday. As of this morning, the Summit recorded 1.1” of snow while Hermit Lake recorded 2.8” of 4% snow. Around dusk last night, wind speeds dropped to calm and shifted from the NW to the NE, before slowly increasing to a current speed of 35mph. Another inch of snow may arrive this morning while wind should shift to the N later in the day. Wind speed may increase slightly this morning before decreasing to the 20-35mph range for the afternoon.

SNOWPACK: March began with a bang in terms of snowfall and was followed by a period of 100mph wind. This left areas of firm wind slab with some areas seeing scouring. The firm wind slab has proven to be edgeable and unreactive to human or natural triggers. Areas of softer snow do exist in Huntington, but it still firm enough to make stopping a fall very difficult. Snow prior to yesterday afternoon will act widespread as a bed surface and should not contribute any volume of snow to an avalanche should one occur. New snow will likely cover variability in the old snow, hiding transitions in textures and possibly leading to mis-steps while skiing or climbing that could lead to a fall.

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  8:00a.m., Sunday, March 25, 2018. A new advisory will be issued tomorrow.

Helon Hoffer, Snow Ranger
USDA Forest Service
White Mountain National Forest
(603) 466-2713 TTY (603) 466-2856