Changes to the 1979–2013 summer Convective Available Potential Energy (CAPE) and extreme precipitation over North America

Trends of monthly Convective Available Potential Energy (CAPE) and single or multiple event extreme precipitation indices, namely RX1day, RX5day R20mm, were analyzed for the summer 1979–2013 over United States (US) southern Canada. A homogeneity test in CAPE data using Wilcoxon-rank-sum showed that statistically significant change points mainly occurred between 2000 2003 probably due to changes humidity sensors during this period. Therefore, trend analysis was split into two categories: regions where no detected 1979–2001 2002–2013 detected. The results show increasing trends indices dominate eastern Atlantic coast US some parts Great Lakes. Mixed decreasing mid-west while western Canadian Pacific had little indices. Although both detected, average RX1day about 0.2 mm/decade 0.5 1979–2013. However, period (RX1day) 1.2 (RX5day) as compared 1.7 Temperatures also increased more (0.3 °C/decade) (0.1 °C/decade). higher recent decades suggests temperatures could potentially lead an overall increase