Author Topic: March 29, 2015: Multiple Avalanches on Mt. Washington  (Read 988 times)

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March 29, 2015: Multiple Avalanches on Mt. Washington
« on: March 30, 2015, 05:43:57 PM »
http://www.mountwashingtonavalanchecenter.org/2015/03/29/march-29-2015-multiple-avalanches-on-mt-washington/

March 29, 2015: Multiple Avalanches on Mt. Washington
 
The date does not escape my attention. March 29, 2014 was the day of an unusual and large avalanche on the summit cone of Mt. Washington, narrowly missing several groups of hikers and skiers. On March 29, 2015, several avalanches occurred on Mt. Washington and Mt. Monroe. Four of these were human triggered. Only one resulted in injuries. We are very thankful for the outcomes of these events, and would Iíd like to share my thoughts surrounding the events in hopes that we can all learn something. Please give these comments some consideration, and rather than point fingers or assign blame, I encourage you to reflect on your own actions and tendencies, and think about how you can increase your margin of safety in the mountains, particularly in regards to avalanche hazard.

The first avalanche 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 (a measure of the force and size, see here for more about this scale), that ran only a short distance downslope. The crown of this avalanche was 50cm deep by 20m wide. The layer that failed was a weak layer of low density snow that had fallen on Saturday with very light winds. Above this weak layer, a slab had formed as winds increased to around 40mph at times. These stronger winds blew snow into a thicker, cohesive layer that we refer to as a slab. Eventually, the size of the slab overcame the strengths that were working to keep it in place on the steep slope, and the avalanche you see in the picture below is the result.

Lower Snowfields avalanche from the morning.
Lower Snowfields avalanche from the morning.
The second avalanche was triggered at about 10:35a.m. in the area of Tuckerman Ravine known as the Lip. 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. More thoughts on this event are provided below, but first letís talk about the rest of the avalanches.

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.

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.
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 ďmassive jump turnĒ 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. This slide propagated around most of the avalanche start zone of Right Gully.

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, stopping by our cabin at Hermit Lake to tell me what had happened.

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 later roped together to finish the climb. On the way they managed to find a 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 averaged about 6″ deep and was about 10′-15í wide.

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 provided transportation for an ill patient from Hermit Lake to an ambulance waiting at Pinkham Notch. So it was a long day, to say the least.

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. Hereís the link to the advisory from March 29th.

Remember, avalanches are a natural phenomenon that donít 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 didnít happen because of something I did or didnít doÖitís 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
Al Hospers
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Offline eyebolter

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Re: March 29, 2015: Multiple Avalanches on Mt. Washington
« Reply #1 on: March 30, 2015, 06:41:57 PM »
I guess I don't feel so bad about having been avalanched since the snow ranger is not immune either.

We had three inches of snow here at 1,100 feet in Western Mass  Saturday, and another dusting today.  Makes for good skiing over the frozen crud, but it must be pretty bad up high.

Offline lucky luke

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Re: March 29, 2015: Multiple Avalanches on Mt. Washington
« Reply #2 on: April 01, 2015, 12:56:05 AM »
I guess I don't feel so bad about having been avalanched since the snow ranger is not immune either.

I guess I was in danger when I have been avalanched since snow ranger is not immune either

Which way of thinking is the safest?