Ober Strasse Avalanche Hazard Warning



 Forecasting Policies


Weather Records







Part of my job is to educate the community club members as much as I can as to the avalanche hazard on the Ober Strasse path.  Remember that three conditions must be met to initiate a slab avalanche.


1.  There must be a weakness in the snow pack that could fail in order to start the slide.

2.  There must be a load on top of this weakness. (enough of a load to cause it to fail.)

3.  No matter the weak layer or how much load on top of it, the weak layer has to be above the anchors on the slope.  It cannot fail and allow the snow to slide if anchors such as trees break up the weakness.  This is the most common situation, which precludes the Ober Strasse path from sliding.  It is infrequent that we reach snow depths great enough to allow a slide to potentially occur.





Through observations of the path since 1997 it appears that it will likely take a weak layer developing on top of a snow pack 10 feet deep in order for a slide to break loose from the tree anchors.  Once there is a weak layer at this height it would take an additional 1 to 2 feet of snow breaking free from the weak layer in order to potentially reach Ober Strasse Road.

I hope to provide a sense of assurance to the residents and a sense of security in knowing that high hazard warnings will likely be limited to those years when we have very deep snow packs.  Barker Consulting will monitor weaknesses in the snow pack and continually watch for any storms that could rapidly increase the snow pack depth.  Residents will be informed promptly of any high avalanche hazard warning.  I want to make sure that residents are not fearful of an avalanche occurring during every strong storm at low or moderate snow pack depths.  While residents can familiarize themselves with the two signs that define the boundaries of the avalanche path, they should not feel that this means there is some hazard every time they go past the signs. The signs will  be changable to show when a high hazard exists.


It is important to note that every year we are accumulating a great deal more knowledge about the Ober Strasse path than we ever had before. When the March 1, 1997 slide occurred no one had ever stood on the slope during a storm and conducted stress tests or observed loading etc. Since official monitoring began in 2002 dozens of individual storms have been observed on site and no movement in the slope recorded at all. This does not mean that a slide could not happen on the slope, only that we started with the most minimal amount of information and history on this slide path.  From that point, it would have been futile to accurately predict the behavior of this path in the future.   In comparison active monitoring since 2002 and assessment of the path during larch avalanche cycles has shown us many situations in which the path will not slide.  A slope's avalanche history is one important factor that avalanche professionals utilize in predicting when that slope may slide.  The Ober Strasse path has not deposited snow on the road since March 1, 1997.  In fact we are dealing with a different slide path than existed in 1997.  The path is much narrower in width now with the construction of the snow fences in 1999.  The path has seen many years of revegetation, whether natural or replanted.  The path will continue to change throughout the coming years as tree growth continues to add an ever-increasing level of stability to the slope.  Tree growth is the key to eventually eliminating the avalanche hazard on the Ober Strasse path and something I cannot stress enough.


The snow pack depths necessary for a slide to reach the road typically do not develop until February in our large snowfall years.  This is an important part of the education program for residents and guests.  Residents should be comfortable with their daily routines and the knowledge that even in very large storms, if we do not have a relatively deep snow pack, the stresses in the snow pack will not be able to overcome the strength of the anchors and an avalanche will not be able to break free.   Just as the past years have provided several times more knowledge about the avalanche path than we had before, the next few years will reveal even more about how the path will react to a greater variety of storms and snow pack depths.


It is my intent to not only monitor the slope for weaknesses in the snow pack, to watch for abnormal snow cycles, and forecast any possible threat to the road but to provide a strong educational platform to the ACC which will increase their confidence as to when the slope will not slide, so that they can go about their daily routines.   I feel it is important to err on the side of caution when we have any set of circumstances, which are likely to threaten the road.   On the other hand I feel I am not doing my job if ACC members are not cognizant of the fact that the factors necessary for the Ober Strasse path to slide to the road just are not present until later in the season, and some years are not present at all.  An accurate assessment of this path and its hazard will lead to a better understanding of the program and more attention being paid when a high hazard warning is issued.  Too much warning, such as the signs being out during all the low snow pack times of the season tends to diminish their validity.  Residents should understand the parameters that would most likely result in a high hazard warning, such as, a very large storm on top of a deep snow pack.  A high hazard warning is not likely with a 24" snowfall on Christmas.


The members can use this education to reach a level of understanding that at the start of the year and in lower snow pack depths all the factors that are necessary to produce a slide are not present. It will take some time each year for the snow pack to build up to a depth that would support a slide, if a weak layer exists and we receive enough input into the snow pack on top of that.  I hope this provides a greater sense of understanding and comfort to the members.  Tree growth is the ultimate answer to the avalanche problem.  In other words as the trees grow the minimum depth required to overcome these anchors will increase.  Each year at the start of the season it will take a greater snow pack depth for the path to become a problem.  The window of time when a member's daily routines on the hill road might become affected will become less and less.  The possibility of a slide occurring will only arise at an ever increasing snow pack depth until the trees are so tall that they provide anchors to a greater depth than the snow pack reaches even in a large winter, thus eliminating the avalanche threat.  Fire, disease and further logging are all factors that could reverse this process of trees adding stability to the slope.


The principal factor in the Ober Strasse path being able to produce a slide capable of hitting the road is snow pack depth. It is my hope that the avalanche monitoring program will not be a mystery to the members, but that it will shed some light and education on the potential avalanche hazard not only as to when increased caution should be used but that members will have a better understanding of the times in winter when the path is not a threat. 


If you have an interest, it is a great idea to get some formal avalanche education.  There are many volunteer organizations, which hold classes or you could take a professional course from the Northwest Avalanche Institute at (360) 825-9261.  There is a great new book about the 1910 avalanche near Stevens Pass.  The White Cascade by Gary Krist recounts the avalanche vs. train disaster that still stands as Washington's deadliest avalanche event.


This Site Developed and Maintained by:
Barker Consulting
34808 Hassinger Road
Lenore, ID. 83541