Avalanche Advisory for Tuesday, January 28, 2014

This advisory expires at 12:00 midnight.

Tuckerman Ravine has Moderate and Low avalanche danger. The Sluice, Lip, Center Bowl, Chute, Left Gully, and Hillman’s Highway have Moderate danger. Natural avalanches are unlikely and human triggered avalanches are possible. Expect heightened avalanche conditions on specific terrain features. All other forecast areas have Low avalanche danger. Natural and human triggered avalanches are unlikely. Watch for unstable snow on isolated terrain features.

All forecast areas of Huntington Ravine have Moderate avalanche danger. Natural avalanches are unlikely and human triggered avalanches are possible. Expect heightened avalanche conditions on specific terrain features.

AVALANCHE PROBLEMS: Today you will be facing a combination of wind slab and persistent slab problems. In this case, new wind slab has formed in a variety of locations, some of which had existing stability issues due to persistent slab. In short, the locations where there are persistent slabs underlying new wind slab have a more complicated and spatially variable distribution of avalanche hazard. Evaluate your snow and terrain carefully.

WEATHER: Today’s avalanche issues are being driven by past weather more so than expected weather today. Over the past three days, the summit is reporting about 9″ (18cm) of new snow. In the last two days, we’ve seen very strong winds, gusting up to 121mph and 114mph each day (195 & 183kph). Except for a brief rise, temperatures have been well below normal. Today we should see winds diminish somewhat, heading down toward 40-55mph (64-88kph) from the W. I expect wind loading to subside today due to limited snow available after such strong winds, along with the decreasing velocities.

SNOWPACK: If you come up to the Bowl today, you’ll see a prominent red flag staring you in the face, as well as a couple smaller ones. I’m referring to a crisp avalanche crown line in the lower portion of the Center Bowl. You can’t miss it. Look around a little more and you’ll also see crowns in other areas near the Headwall, such as the Lip and near the Chute. These are excellent indicators of unstable snow! The Center Bowl avalanche is recent, some of the others are as old as lunchtime on Sunday.

The snowpack right now is an intensely variable mix, due to previously existing faceted layers under hard slabs, new wind slab from the last 24-48 hours, and the recent avalanche activity with various degrees of reloading. If it weren’t for the persistent slab/facet layer, the recent winds may have been strong enough to bring some areas down to Low danger. Most of Huntington is one example, Hillman’s Highway is another. These areas often see a lot of scouring when winds are as strong as they were. However, the persistent nature of the existing instabilities gives me insufficient confidence that these locations are stable enough to call Low. Keep in mind that the snow underfoot may feel hard and strong, but there may be weak layers lurking underneath waiting for you to reach a thin spot or other weakness. Constantly be assessing the snow as you move through the terrain 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. January 28, 2014. 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

2014-01-28 Print Friendly