Avalanche Advisory for Wednesday, February 24, 2016

This advisory expires tonight at 12:00 midnight.

All forecast areas of Tuckerman Ravine will have Considerable avalanche danger. Dangerous avalanche conditions will exist. Natural avalanches will be possible and human-triggered avalanches will be likely. The Lobster Claw, Lower Snowfields, and Little Headwall remain not posted due to an overall lack of snow in these areas.

Huntington Ravine has Considerable and Moderate avalanche danger. Yale, Central, Pinnacle, Odell, South, and the Escape Hatch have Considerable danger. Natural avalanches are possible and human-triggered avalanches are likely. North and Damnation gullies have Moderate avalanche danger. Natural avalanches are unlikely and human triggered avalanches are possible.

 AVALANCHE PROBLEM: Avalanche danger will be increasing quickly today as new precipitation changes from snow to a wintry mix and then to rain. All areas will be increasing in danger, but the type of problem you’ll find depends on your aspect and timing. Early on, the dominant problem will be wind slab, either previously existing or newly developing slab from today’s snowfall. Later, as temperatures rise, you will be faced with a wet slab or wet loose avalanche problem. New wind slabs will build primarily on N-facing slopes, and to a lesser degree on E-facing slopes. Prior to new snow, problems existed largely on E-facing slopes such as Chute and Lip in Tuckerman or Central and Pinnacle in Huntington.

WEATHER: It’s these types of storms that make New Englanders a hardy bunch. A few inches of snow followed by record breaking warm temperatures and heavy rain, only to be followed by a sharp drop in temperatures before the weekend. Today we can expect up to a few inches of snow to fall before we start to see a wintry mix of precipitation types. This will come in on a S wind in the 35-45mph (56-72kph) range. As the changeover takes place, the wind speeds will start to increase significantly with hurricane force gusts in the afternoon. Temperatures will rise today, easily surpassing the freezing mark at all elevations, likely breaking records in the nighttime. Total liquid equivalents for this storm will be somewhere between 1″ and 3″, most of which will come as rain overnight and on Thursday.

SNOWPACK: The key to today’s advisory is to understand that we will have increasing avalanche danger on a variety of aspects due to new snow and rain. If you need (or want) deeper information than that, I hope it’s only for your personal interest, and not to help you make travel decisions. But here it is anyhow…We had a widely variable range of stability out there prior to new snow this morning. Good to fair stability could be found in much of the terrain, but our observations kept bringing us back to a Moderate rating due to there being too many different layers in a highly variable snowpack. Much of the slabs we found were 1F hard with weak interfaces within the slab at various depths above the weakening crust. I could see avalanche activity in today’s wind slab stepping down into these layers, or as rain saturates the snowpack, the failure initially being at or below the crust layer. All told, it’s a fairly complex snowpack for now, so focus your attention on the weather today and you’ll be see the most important data.

The Lion Head Winter Route is open and the recommended east-side route to the summit that avoids avalanche terrain. The John Sherburne Ski Trail is icy and challenging beneath a veneer of new snow.

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 the Harvard Cabin.
  • Posted 8:15am, February 24, 2016. A new advisory will be issued tomorrow.

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