[Updated February 3, 2016] As of February 1, there have been sixteen avalanche accidents resulting in fifteen fatalities across the US this winter. Thirteen of the deaths occurred in January 2016, with ten of them occurring in the span of nine days between January 16 and 24. Two of the fatalities occurred in Colorado. This is a very large number of fatal accidents in a relatively short period. We can look at previous winters to see how unusual this cluster of accidents is. Unfortunately, the answer is “unusually bad.”
Since 1950, January is the month with the most avalanche fatalities. The 12 fatalities in a single month is the largest number of fatalities in January since 2008, when 19 people died in avalanches. The winter of 2007-08 was one of the worst seasons for avalanche fatalities in the last 65 years.
In the last 15 winters, February has taken a slight lead, with 22% of the total fatalities compared to 21% in January. During that period there have been between 2 and 6 fatalities in January. In addition to January 2008, only February 2014 (12 fatalities) and February 2012 (13 fatalities) had similar numbers of avalanche deaths within a month. The 2011-12 and 2013-14 seasons were also among the worst seasons for avalanche deaths in the last 65 years.
Total avalanche deaths by month, winters 2001-2015. The red line indicates the average of cumulative fatalities through the season.
Avalanche deaths by month, winters 2001-2015. The red “x” mark median values.
In the United States, about 70% of fatal avalanche accidents occur within four days of a prior accident (Logan and Witmer 2012). These clusters results in long accident-free periods, then a period with several accidents, followed by another long accident-free period. Within a cluster, it can feel like an unusually high number of accidents.
The statistical analysis does not reduce the pain and loss with each fatality. Each one leaves a hole in the heart of the victim’s family, friends, and community. The analysis does help us place current tragedies within a longer context. There have been an unusual number of accidents recently. This may be an indication of how accident patterns will evolve over the rest of the winter.