Recent observed trends and modeled interannual variability in Canadian snow cover

Analysis of Canadian daily snow depth data revealed a consistent reduction in the duration of snow cover over the period of record (1955-89). This was most marked in southern regions of the Prairies and western Canada where the annual duration of snow cover has decreased an average of 1.0 to 1.5 days/yr over the 35 year period. Most of this decrease occurred in the spring in association with significantly warmer spring temperatures. Analysis of reconstructed snow cover duration data from 1900 in three regions (W. Prairies, S. Ontario and Maritimes) revealed quite different responses and scales of variability. However, a characteristic feature of the data was a trend toward increasing snow cover duration from the late-1920s to the late-1960s, followed by a rapid decrease during the 1970s and 1980s. The lack of a consistent relationship between snow cover and air temperature highlighted the complex nature of snow-climate interactions in Canada.