Weekend Update for March 23-24th

It sure was nice to see another big avalanche cycle this week. There’s lots of debris across the entire floor and easy to see where it came from, Sluice. The crown line wrapped from the buttress between Right Gully and Sluice across the ice and around toward the Lip, running right over “Lunch Rocks” across the floor and into the bushes below Left Gully. This should serve as a little reminder to anyone hanging out in the floor and thinking they’re not in avalanche terrain. Once you get to the first aid cache, under the current conditions, YOU ARE IN AVALANCHE TERRAIN![singlepic id=862 w=320 h=240 float=right]

Piecing together the cycle it looks like Left Gully ran during the storm, as well as the Lip and Center Bowl. The most recent was Sluice covering much of the debris from the others. Frank and I got up to the crown-line not before getting through some seriously hard old surface, seriously hard. We checked out the far climbers right of Sluice and measured it between 30 and 40 cm deep. If you had plans to get some skiing in near Sluice, the bed surface gets harder the higher you go, and then there’s that hang-fire looming overhead. The good news is that there are some other options that would appeal to a skier or snowboarder today, but light is fading fast and the weather is dropping visibility as well as dropping some snow flakes. Based on increasing winds and a winter like day in store for Saturday you might have missed out, but I’ll leave the details to Jeff……

Looking ahead at the weather for the upcoming first weekend of spring, I’m sorry to say that it won’ t resemble spring much at all. In fact, it won’t even resemble a nice wintery day. “Full winter conditions” are what you can expect for Saturday. Upslope snow showers are a likely scenario for tomorrow. Temperatures will be cold and NW winds will be ramping up to speeds that make it very difficult to simply stand upright. Not only will this make traveling above treeline a challenge, but it will relocate snow from wherever it currently sits to somewhere on the eastern flanks of the mountain.

As far as avalanche danger is concerned, you can expect increased danger ratings tomorrow in Tuckerman and Huntington based on the wind loading that will likely be taking place. If speeds get very strong, there might be some scouring taking place, but I wouldn’t bet my life on it when I can’t see what’s going on above me. On Sunday, clouds will persist but winds will be on the decline, though not reaching too low of speeds. So overall, I would probably not expect to get too far into avalanche terrain this weekend without taking on a good amount of risk. While our forecasts are focused on the Cutler River Drainage, I would also expect increased risk of avalanches tomorrow in many of the other gulfs and ravines around the Presidentials, especially those with a E or S aspect.

One additional note: The Little Headwall and brook leading out of the ravine have improved with the new snow, but they are still not without hazard. Skiers today had a couple close calls where they collapsed the weak snow bridges in the streambed. [singlepic id=871 w=320 h=240 float=center]

Joe and Jeff

Avalanche Advisory for Friday, 3-22-2013

This advisory expires at 12:00 midnight, March 22, 2013.

All forecast areas of Tuckerman and Huntington Ravines have MODERATE avalanche danger. Natural avalanches are unlikely and human triggered avalanches are possible. Heightened avalanche conditions exist. Evaluate snow and terrain carefully and identify features of concern. The only exception is the Little Headwall, which has Low avalanche danger. Watch for unstable snow in isolated terrain features here.

Today we are treated to an unexpected bluebird morning in the ravines, which is allowing us to get great visual observations of what’s taken place here since the latest storm began. On the whole, it’s definitely a “heads up” kind of Moderate today. The storm dropped a large quantity of snow across the mountain, which was subsequently blown into the ravines on strong NW winds and produced numerous avalanches in many locations. Recent avalanche activity is a red flag that should heighten your awareness of the avalanche risk. This morning that red flag is standing straight out and strong in the relatively windless ravine. If winds increase as forecasted and additional snow loading begins to occur, that is another red flag and should cause you to reconsider whatever plan you have made. 

The stability problems we’re dealing with today are the result of the aforementioned storm and wind event. Snow began on Tuesday, but it wasn’t until Wednesday morning that the winds shifted to the NW and increased in speed. This created a situation of significant windslab development across all aspects. Avalanches occurred at various times during the storm, which allowed some slopes to see a lot of reloading while others still show sharp crown lines indicating they took place later in the avalanche cycle. Thursday ended with clear skies and some solar gain on S-facing slopes. This created a sun crust on some of these aspects, but I doubt that the sun’s effect was strong enough to completely stabilize these slopes. In fact, it just might be enough to provide a false sense of stability if one were to only make assessments in the upper layers, such as with a ski pole probe or the feel of snow beneath one’s skis.

We often are able to pick out a couple specific areas where we have our greatest concerns. Today, new windslab is sufficiently widespread to make just about all areas an “area of concern.” For example, in all locations of Tuckerman I would be cautious about venturing up without a clear idea of why I was going there. Sluice did have a recent avalanche, but there is still a large amount of hangfire sitting in very steep terrain above the crown line. The Lower Snowfields, Right Gully, and Lobster Claw are the areas with the lowest likelihood of avalanches today, but they still easily fall within the Moderate range.

Huntington has stability concerns in many areas as well. In Yale, Damnation, and North, the problems are greatest in the mid-sections of the gullies. Central has a lot of new slab throughout. Pinnacle and Odell have slab on the approach to the ice as well as up above the ice. We’ve had lots of accidents and close calls on these approaches after similar events, so be sure to begin assessing snow carefully long before you swing a tool. South and Escape Hatch have a lot of windslab near the exits. So as you can see, the problems truly are widespread today.

Enjoy the sunshine while we have it. The forecasted weather was for summits being firmly entrenched in fog, so visibility may deteriorate rapidly at any time today. We’ll have an Weekend Update for you this afternoon or evening after our field work today.

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 8:40 a.m. Friday, March 22, 2013. 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

2013-03-22 Printable