Monday, 14 January 2002: 4:45 PM
Trend analysis of the 20th century snowfall record for Minnesota
In the upper Midwest, seasonal snowfall is a major contributing factor to the economy of the region, affecting commerce, industry and tourism and recreation. Snowfall is highly variable both temporally and spatially and can vary considerably in liquid water equivalence. Recently, a database of snowfall and liquid equivalent precipitation has been compiled for Minnesota consisting of over 400 observing stations throughout the state. A significant portion of these stations has a period of record representing conditions back to the late 1880's. Using this high density data, snowfall statistics, snowfall trend analysis and snow water equivalent (SWE) statistics are generated. The analysis suggests a positive snowfall trend for the 20th century, with a mean change in average annual (July - June) snowfall of approximately 1.0 - 1.5 in per decade. Furthermore, the increase is evident in the months of November, December, January, with February and March indicating a slight decline in monthly snowfall. SWE is variable throughout the winter season with the higher ratios (water depth / snow depth) of 0.14 found in November and March (indicative of wetter snowfall events) and lower ratios (0.07 - 1.0) for December, January and February. Also, there is north-south SWE gradient indicating wetter snow events in southern Minnesota and drier events in the north.