Twenty-first century increases in total and extreme precipitation across the northeastern USA

Abstract

The northeastern USA has experienced a dramatic increase in total and extreme precipitation over the past 30 years, yet how precipitation will evolve across the Northeast by the end of the twenty-first century remains uncertain. To examine the future of precipitation across the Northeast, we use the Weather Research and Forecasting (WRF) regional climate model driven by the National Center for Atmospheric Research Community Earth System Model (CESM) to simulate precipitation for historical (1976-2005) and future (2070-2099) periods. We compare precipitation from CESM-WRF hindcasts to gridded observations (Daymet), finding a 4.6% dry bias and 7.7% wet bias for total and extreme precipitation, respectively. CESM-WRF projections have increases in both total (9.7%) and extreme (51.6%) precipitation by the end of the twenty-first century, with winter having the largest increases in total precipitation (16.4%) and extreme precipitation (109.3%). These results are consistent with additional WRF simulations forced with the Max Planck Institute Earth System Model and the North American Coordinated Regional Downscaling Experiment archive. To investigate the drivers of precipitation change, we analyze several atmospheric variables and find that the projected increases in extreme precipitation are strongly related to increasing precipitable water over the eastern USA and the Atlantic Ocean. Understanding projected increases in total and extreme precipitation is critical for stakeholders to prepare for the impacts of intensified precipitation.