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Heavy precipitation and the resulting flooding are the most serious weather-related hazards over the west coast of North America. This paper analyzes the trends in heavy precipitation for the period 1950--2009 by examining the decadal distributions of the top 60, 40, and 20 two-day precipitation events for a collection of stations along the coastal zone of the United States and British Columbia, as well as the decadal distribution of maximum daily discharge for unregulated rivers from northern California to Washington State. During the past 60 years there has been a modest increase in heavy precipitation events over southern and central coastal California, a decline in heavy events from northern California through the central Oregon coast, a substantial increase in major events over Washington, and a modest increase over coastal British Columbia. Most of these trends are not significantly different from zero at the 95%% level. The trends in maximum daily discharge of unregulated rivers are consistent with the above pattern, with increasing discharges over the past three decades over Washington and northern Oregon and declines over the remainder of Oregon and northern California. Finally, the above trends in heavy rainfall and daily discharge are compared to the future patterns indicated by general circulation models under various global warming scenarios. [ABSTRACT FROM AUTHOR]

Abstract: In this paper we present a study concerning the climatic behaviour of two principal observables, temperature and precipitation as obtained from the measurements carried out at 50 Italian meteorological stations, since 1961. Analyses of WMO Climate Normals (CliNo) from 1961 to 1990 have been performed dividing the 50 Italian stations in three different classes: mountain (11 stations), continental (17) and coastal areas (21). The comparison of the CliNo 1961–1990 with the trend of temperature and precipitation for the period 1991–2000 showed a sharp significant increase of summer temperatures over Italy starting from 1980. This phenomenon was particularly evident for mountain stations, where a significant temperature increase has been recorded also during the autumn. Moreover, the analysis of precipitation data permitted to point out that, starting from 1980, mountain stations have been affected by a significant increase of precipitation events during autumn and winter, while for the rest of the Italian territory a reduction of precipitations has been recorded during early spring. [Copyright &y& Elsevier]