TEMPORAL PATTERNS OF DIURNAL SNOWMELT ACROSS THE NORTHERN GREAT PLAINS OF THE UNITED STATES

Abstract

The purpose of the work presented here was to examine the temporal pattern of daily snowmelt across the northern portion of the Great Plains of the United States for the three-month winter season, December, January, and February (DJF), for the 60-year period 1933–1934 through 1992–1993. A three-month spatial climatology of snow cover (duration and depth) was constructed for the region along with a 60-year temporal analysis of areally averaged snow cover. A spatial climatology of diurnal snowmelt, stratified by the magnitude of melt, also was constructed for the region, as was a temporal analysis of the areally averaged melt events by both frequency and fraction of total melt events falling within the different magnitude categories. The research has indicated that the largest changes in the characteristics of snow cover and snowmelt across the northern Great Plains during the 60 years occurred during the first 25 to 30 years. A secondary trend in the characteristics occurred during the mid- to late 1960s. Early in the record, mean regional snow cover duration increased, the frequency of stable diurnal snowpacks (no daily melt) increased, and smaller melt events became more frequent than large melt events. Over the latter portion of the record, no appreciable trends in the variables are evident. [Key words: diurnal snowmelt, Great Plains, climatology.]