Weekend Update, Friday, January 11, 2013

If there was any doubt in your mind that Old Man Winter is especially fickle in New England, you can cast all doubts aside.  A warm air mass moving into our area today will bring some freezing rain to what has been a nice early season snow pack for skiing and riding.  Though the freezing rain totals will be on the light side (less than 1/10th of an inch), expect the warming temperatures on Saturday and Sunday, coupled with plenty of  fog to do some damage to our existing snowpack.  Should precipitation turn to rain, be aware of an increasing avalanche hazard due to the added weight of rain in the upper layers of the snowpack, the  lubrication of ice slabs and the breaking down of bonds between snow layers due to warming and thawing of the connections between snow grains.  As an avid skier, I hate to hope for freezing rain but given rain as an alternative, I’ll take the frozen variety.  As of Friday at 5pm, the National Weather Service is predicting freezing rain.

If skiing or riding is on your to do list this weekend, the resorts should offer good carving conditions and short lift lines. I wish I could say that riding will be great in Tuckerman Ravine and on local ski trails but the sad fact is that our snow cover is fairly thin and may get hammered by the snow eating fog and rain Friday night and then by the potentially record breaking warm temperatures on Saturday and Sunday. Currently, our snowpack in the Ravines consists of mostly medium-soft windslab with areas of  ice crust from our rain-on-snow event on December 21st.  Backcountry travelers should consider the consequences of adding heat to the snow which will make trails and packed snow “punchy” with postholing a real threat in areas of deeper snow.  Climbers venturing into gullies and ice climbs should check our daily avalanche advisory for the latest forecast since we will be closely watching weather data for red flags that indicate instability within the snowpack. Another incoming low pressure system on Sunday may bring more light rain.

Later in the week, we should return to more seasonable temperatures and hopefully a storm track that will be kinder to the snow lovers among us.  For now, lets hope our snowpack holds up until then.

Frank Carus, Snow Ranger

 

 

Avalanche Advisory for Friday, 1-11-2013

Expires at 12:00 midnight, Thursday 1-10-2013

Tuckerman Ravine has Moderate and Low avalanche danger. The Sluice, Lip, Center Bowl, and Chute have Moderate avalanche danger. Natural avalanches are unlikely and human triggered avalanches are possible. All other forecast areas have Low avalanche danger. Natural and human triggered avalanches are unlikely except in isolated terrain features.

Huntington Ravine has Moderate and Low avalanche danger. South Gully has Moderate avalanche danger. Natural avalanches are unlikely and human triggered avalanches are possible. All other forecast areas have Low avalanche danger. Natural and human triggered avalanches are unlikely. Watch for unstable snow on isolated terrain features.

Two nights ago approximately 4-5” (10-13cm) of snow fell on Mt. Washington which was thoroughly redistributed by very strong NW winds yesterday. For the time being, the stability concerns we have today are related to how and where this snow was moved. In both ravines, much of the snow was carried from upper elevations down in the lower portions of the avalanche terrain. Although both ravines have areas forecasted as Low danger, remember that pockets of unstable snow can exist within this rating. A good example of the fine line that can exist between Moderate and Low can be found in Huntington. We’re rating South Gully as Moderate due to the size of the snowfield in the lower third of the gully. It would be difficult to avoid this without actually leaving the slide path. Below Yale and Damnation pockets also exist where the force of the wind was lesser and therefore strength is lower. However, these areas of loaded snow are smaller in size and there are options for people to get around them if they needed to. So it’s a similar problem but a slightly different scale. Regardless of which gully you are approaching, be aware of the potential for steep snowfields to have unstable slabs, and look to stay on the hard wind effected snow when it’s available.

In Tuckerman, Hillman’s Highway and Left Gully are mostly scoured and wind-hammered, and therefore will have good stability. As you look around toward the Center Bowl, you’ll see patterns in the snow indicating it was wind effected, but the protected nature of this area calls into question the visual clues. This area is still broken up by exposed rock and ice, and some terrain features are only recently buried. Even if you’re traveling over snow with generally good strength, if you hit one of these thin spots you could propagate a fracture out into deeper, stronger snow. As you move toward the Lip and Sluice, expect softer windslabs with less strength, which will be more prone to human triggers. Right and Lobster Claw are still developing their snowfields, so there is not widespread instability in these areas. The mouth of Right and the top climbers’ left side of both gullies are terrain features where unstable snow may exist.

Warm weather is in the forecast, including light freezing rain tonight and above freezing temperatures through the weekend. We’ll be keeping tabs on how this will affect snow conditions. Later this afternoon we’ll post a Weekend Update with our most current thoughts. Be sure to check the morning avalanche advisory each day before heading into avalanche terrain!

We have opened the Lion Head Winter Route for the season. This is a steep mountaineering route, and we strongly recommend bringing an ice axe, crampons, and the ability to effectively use these tools.

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 8:45am, January 11, 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

2013-01-11-Print