Mid-21st century anthropogenic changes in extreme precipitation and snowpack projections over Newfoundland

Abstract Extreme precipitation events, including probable maximum precipitation (PMP) and probable maximum snow accumulation (PMSA) and 1/100 annual exceedance probability (AEP) values for precipitation (P100) and snow accumulation (expressed in snow water equivalent; SWE100) were analyzed over Newfoundland to compute the projected changes from 1971–2000 to 2041–2070. PMP and PMSA of various storm durations were simulated based on the moisture maximization of high efficiency storms. Also, P100 and SWE100 data were calculated based on the frequency analysis of liquid precipitation and snowpack data during each 30-year period. The required meteorological variables, including liquid and solid precipitation, precipitable water content, and snow accumulation, defined over a 50 × 50 km grid, were extracted from an ensemble of six regional climate model simulations provided by the North American Regional Climate Change Assessment Program (NARCCAP). Projections indicated that while PMP and P100 are intensifying in the future period, PMSA and SWE100 are declining. This is the first study which quantifies the impact of climate change on extreme-value characteristics of precipitation in Newfoundland. The results of the study can help stakeholders throughout the province to gain a better understanding of the impact of global warming on extreme meteorological events. Such an understanding is prerequisite to build resiliency and understand the uncertainty related to standard probable maximum flood analysis in the region.