Since 2015, southern states including Texas, Louisiana and Missouri have seen consecutive episodes of severe flooding, each caused by record precipitation of various origins. This project will be an advanced technology demonstration, following a pilot study (RC-2709), to improve the understanding and capability of anticipating extreme hydroclimatic events in southern states. This project develops a novel combination of large-scale climate diagnostics and storm-scale simulations: (a) examining the climate/ocean controlling factors for the spring rainy season and then applying this understanding to evaluate the multi-year prediction produced by an earth system model; (b) conducting fine-resolution downscaling to add detailed simulations of storm characteristics and to derive extreme-weather metrics that are useful to installation managers.

Two main modeling approaches will be used for this project. One conducts a series of partial data assimilations to understand the different oceans’ impacts on the Pacific climate predictability. The other engages in convective-permitting modeling (CPM) at kilometer scale resolution. Analysis will utilize the new Decadal Prediction Large Ensemble Project (DPLE) of the Community Earth System Model, the same model used in the pilot study, for the evaluation of reforecasting ability and for diagnostics of the source of predictability. The DPLE output will be downscaled with the aforementioned CPM approach to derive metrics that are understood and used by most engineers, namely probable maximum precipitation. Finally, outreach activity in translating the prediction into perceivable risks will be engaged to facilitate decision making.

This project will assist in improving prediction capability beyond two years for extreme hydroclimatic events in U.S. southern states. In the face of the recent extreme rainfall experienced by Texas and its neighboring states, such as the massive floods during 2015-2018, the National Guard has been called upon frequently to support civil authorities and provide disaster relief. By offering greater threat visibility, years ahead of time, this research can help strategic decision-makers make decisions about guard and reserve deployment cycles. Besides aiding management decisions for Department of Defense installations, well-planned and executed local disaster relief will also facilitate global military operations, which have been impacted by the increase in demand for military support in the aftermath of extreme events worldwide.