Changes in temperature and snowfall patterns at Big Bear Lake, California from 1960-2010

The purpose of this study was to understand whether there have been changes in winter <bold>temperature</bold> and <bold>precipitation</bold> patterns at <bold>Big Bear Lake</bold>, <bold>California</bold> by using daily synoptic observations from 1960/61 to 2009/10. A correlation analysis was performed to observe the effect that increasing <bold>temperatures<bold/> have had on <bold>snowfall</bold> and rainfall patterns. Also, the impacts of the El Ni??o/La Ni??a phenomenon on the first/last dates of snowfall, length of snowfall season and number of snowfall days are also examined. There were a number of significant findings. The cold season air temperature, during the last 50 years, has been increasing significantly at a rate of about 0.667&deg;F per decade, which is greater than the global mean temperature trend of 0.22&deg;F per decade (IPCC, 2007). Both snowfall days and rainfall days are negatively correlated with the air temperature in the winter season. Also, as air temperature increases, there's an earlier occurrence of the last snowfall day and thus a reduced snowfall season. The El Ni??o/La Ni??a phenomenon also had a significant affect on snowfall patterns. During El Ni??o years, the snowfall season started about 37 days earlier and lasted about 33 days longer than La Ni??a Years. There were also 13 more snowfall days during El Ni??o years than La Ni??a years. Overall, the <bold>warming climate</bold> has significantly affected snowfall and precipitation patterns at Big Bear Lake, California