A storm rating scale based on impacts for a warming climate has been developed using precipitation intensity duration frequency (IDF) and Atmospheric River (AR) concepts. Initially devised as a five-level scale, it incorporates antecedent moisture conditions and sensitivity to water input rate and duration. Our ECAR team of Environment and Climate Change Canada, Vancouver BC, along with the Climate Research Division in Victoria, BC, led this initiative with assistance from numerous Canadian scientists despite challenges presented by COVID pandemic isolation. Dr. Matthias Jakob of BGC Engineering, the BC River Forecast Center, and AR experts from NOAA-USGS and UC Santa Barbara also provided significant contributions._x000D_ The ECAR scale is grounded in the concept of Atmospheric Rivers, which involves vertically integrated vapor transport and storm duration, linking precipitation intensity and duration to impacts based on engineering criteria, local hazards, and expertise. This storm rating scale holds considerable potential in improving natural hazards forecasting, providing "Heads up" advisories days to weeks in advance. Projections indicate that future storm impacts will be more severe based on Atmospheric Rivers, with a warmer climate expected to bring more intense and frequent storms than our current engineering can withstand._x000D_ To address increasingly frequent and intense storms, the scale now includes eight levels, although level 5 remains catastrophic according to current engineering design criteria and historical IDF statistics. Findings suggest that substantial enhancements in emergency designs and infrastructure are necessary to adapt to the anticipated changes resulting from ongoing global warming.
