Mar 302015
 

This advisory expires tonight at 12:00 midnight.

Tuckerman Ravine has Considerable and Moderate avalanche danger. Sluice, Lip, Center Bowl, Chute and Lower Snowfields have Considerable avalanche danger. Natural avalanches are possible and human triggered avalanches are likely. Lobster Claw, Right Gully, Left Gully and Hillman’s Highway have Moderate avalanche danger. Natural avalanches are unlikely and human triggered avalanches are possible. The Little Headwall has Low avalanche danger. Natural and human triggered avalanches are unlikely.

Huntington Ravine has Moderate and Low avalanche danger. Central, Pinnacle, Odell, South and Escape Hatch have Moderate avalanche danger. Evaluate snow, weather and terrain carefully. North, Damnation and Yale have Low avalanche danger. Natural and human triggered avalanches are unlikely. Watch for unstable snow in isolated terrain features.

AVALANCHE PROBLEM: Wind Slabs developing today, in some areas on an already poor snow structure, are the primary problem. With the exception of the Lip, which was raked down to the bed surface yesterday, Considerable rated areas contain the largest expanses of older wind slab going into today’s weather event. This wind slab was reactive to human triggers yesterday and is most likely still reactive. South facing gullies in both Ravines, though still containing pockets of the older wind slab, benefitted from a period of settlement yesterday due to warming and, in Tuckerman, was also cut up by ski traffic.

WEATHER: Wintry weather continues as a cold front pushes through today bringing some moisture and wind to the region. The main weather factor affecting stability will be the wind. Currently, west winds in the 50 mph range are pushing some snow into east aspects. The wind is expected to pick to the 50-70 mph range later today. These wind speeds are the highest since roughly 6” of snow fell late last week which means that there is enough snow laying around higher terrain to provide the building blocks for new hard wind slabs. Light snow and snow showers through the afternoon hours may contribute 1-3” more snow to the slab building process.

SNOWPACK: Avalanche danger is starting out one rating lower in each forecast area that isn’t already rated Low. The above ratings are based on wind transported snow, plus 1-3” of new snow falling today, which will cause danger to rise.

A crown profile in the 50cm x 20m natural avalanche in the Lower Snowfields revealed that the failure layer of the slab was within soft (4F) snow and rimed snow particles. The overlying harder slab (1F) was softer than we often see due to the light winds that built it being only around 40 mph. This crown thickness and structure is very similar to that in the much larger Lip avalanche and is the same as you might find in other slopes and gullies, only in varying thicknesses and distribution.  In summary, signs of recent avalanche activity in the previous 24-48 hours are one red flag to consider today. Another is active wind loading, as evidenced by snow moving along the ground at the ridgetop and above treeline, A third is a small amount of new snow and a weather forecast that includes wind speeds capable of moving that snow and building wind slabs. It’s pretty hard to miss these signs today, so if you choose to enter avalanche terrain, do so very carefully and limit time spent in avalanche runouts or, better yet, avoid them entirely.

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 8:16 a.m. Monday, March 30, 2015. A new advisory will be issued tomorrow.

Frank Carus, Snow Ranger
USDA Forest Service
White Mountain National Forest
(603) 466-2713 TTY (603) 466-2713

2015-03-30

Mar 292015
 

I know the word is beginning to hit the street, and in an effort to help keep facts straight I’m posting some information now. I hope to update this post on Monday after a good night’s sleep, but don’t be too surprised if it takes until Tuesday.

There were six avalanches that I’m aware of on Mt. Washington today. Four of these were human triggered. Only one resulted in injuries.

The first was early in the morning. A small slab naturally released from the Lower Snowfields. The exact timing is uncertain, but I first noticed it after posting the advisory at Hermit Lake at 8:30a.m. This was a small slide, D1R1, that ran only a short distance downslope.

Lower Snowfields avalanche from the morning.

Lower Snowfields avalanche from the morning.

The second avalanche was triggered at about 10:30a.m. by me in the Lip as I was attempting to collect snow stability information. This was a fairly large slide, D2R3, approximately 2′ or more at the deepest part of the crown. I was caught in the debris and carried several hundred feet downslope, coming to rest on top of the debris and uninjured. The debris pile was approximately 3-4′ deep on average and spread out 400′ or more down the floor. No measurements were taken, this information is an estimate.

20150329_113239

Photo from Mt. Washington Observatory webcam at the top of Wildcat.

Photo from Mt. Washington Observatory webcam at the top of Wildcat.

20150329_110637

Snowboarder about to try to ride a slick icy bed surface.

Not more than 30 minutes after the slide, we saw a snowboarder sitting at the top of the Center Bowl, up above the ice. He traversed back to the Lip, where he made a less-than-spectacular descent on his heel edge down the entire bed surface. This was a much better choice than trying to ride the other side of the Center Bowl or Chute where there were still significant stability concerns. Had the Lip not been triggered, and he had descended this route, I feel pretty confident in saying he would have triggered an avalanche and been carried down from a much worse location than I was when it happened.

The third avalanche occurred at about 11a.m. Solar heating released a chunk of ice from the Sluice, which triggered a small D1R1 avalanche in the far right side of the Sluice under the ice. No one was near the slide at the time.

This is after the slides in Sluice and Right Gully. You may be able to see both crown lines.

This is after the slides in Sluice and Right Gully. You may be able to see both crown lines and the portion of the Lip avalanche that reached into the Sluice.

At about 12:00 noon, the first skier to attempt to descend Right Gully made a what witnesses described as a “massive jump turn” into what was the deepest area of windblown snow near the skiers right side. This triggered a thin slab (4-10″ deep by several estimates) that carried the skier downslope a few hundred feet. He was able to get away from the moving debris before it spilled through the mouth of the gully and into Lunch Rocks.

Later in the afternoon, I received a firsthand report of a skier triggered slide in Oakes Gulf. This slide was estimated to be about 2′ deep and 80-100′ wide with a vertical run of 500-600′. The skier was not caught in the debris and was able to keep on with his day.

On my descent from Hermit Lake, I needed to stop at the Harvard Cabin. Here I learned of the sixth avalanche. A guided party was practicing lead climbing in South Gully of Huntington, when an unroped party of three passed them. They then managed to find a small pocket of unstable snow and trigger it, releasing enough snow onto the leader to cause her to fall. The fall pulled out a couple of snow pickets, but her ice screw in the bulge held, and the belayer (who was anchored to the ice) was able to catch the fall. She suffered minor injuries from the fall. This slab was only about 4-6″ deep and about 10′ wide. Ample opportunities existed for the passing party to avoid the unstable snow, but for reasons unknown to me or the affected party, they chose to travel into the unstable pocket.

Finally, on my drive home in the evening, I received a call for a medical incident at Hermit Lake. There is not much to report here, we just provided the patient a ride from Hermit Lake to Pinkham Notch. So it was a long day, to say the least.

The short version of the snowpack info is that there was a crust layer formed on Thursday and Friday. Snow on Saturday began with very low densities and very low winds, some rimed crystals were in this snow. Winds eventually kicked up to the low 40mph range, building soft slabs on top of a very weak layer, which was on top of a crust layer. This is a classic recipe for instabilities.

More info is to come about the conditions, my thought process, and my feelings on the events from this day, including how I feel about the advisory I wrote in the morning. I feel very fortunate to have escaped unharmed. Many thanks to everyone who listened to our safety messages from the day and took appropriate action. Here’s the link to the advisory from March 29th.

Remember, avalanches are a natural phenomenon that don’t care who you are, what you know, or how good of a skier/rider/climber you are. They treat people indiscriminately and often ruthlessly. I feel fortunate to have escaped unharmed, but that didn’t happen because of something I did or didn’t do…it’s because I was lucky. By sharing this incident, I hope that others can develop a strong sense of respect for these events and do everything possible to not be involved in one.

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

 

 Posted by at 10:14 pm