Shifts in End of 21st Century CONUS Consecutive Dry (Wet) Days

Agricultural industries and stakeholders are particularly sensitive to climate variability. For the wide array of crops grown in the CONUS, the diversity of favorable growing conditions and atmospheric hazards enhance the difficulty of generating future climate projections at the spatiotemporal scales relevant to agriculture. High-resolution, convection-permitting regional climate models capable of informing projections of future climatic shifts at the multitude of scales relevant to agriculture are computationally expensive. As such, few simulations have been produced for long periods (i.e., > 10 years), and most of the affiliated literature has focused on hazardous convective weather. This research seeks to leverage the strengths of these regional climate models to examine agriculturally important trends in annual and growing season precipitation, specifically focusing on potential changes in the frequency and duration of dry and wet periods over annual and seasonal time frames. First, a historical baseline (1990–2005; HIST) of precipitation is established and compared against observations. Next, HIST is compared to two end-of-21st century (2085–2100; FUTR) climate change simulations based on representative concentration pathways (RCP) 4.5 and 8.5. Quantitative comparisons between HIST and FUTR indicate a general increase (decrease) in the number of dry (wet) days by the end of the 21st century across all CONUS regions, with few sub-regional exceptions. The distribution of more dry days within a fixed period naturally leads to an increase in two or more consecutive dry days (CDDs; < 0.254 mm day-1). The most substantial increases of CDDs occur in the Southwest and along portions of the Atlantic Coast. Preliminary analysis of intraseasonal occurrences of CDDs indicates substantial shifts of CDDs with some areas experiencing advancement of CDDs in the calendar year and others experiencing delay. This variability in occurrences of dry/wet conditions during the growing season may impact agricultural pest management, field operations, and pose additional challenges to other agricultural sectors.