Abstract

The flash flood event of 23 June 2016 devastated portions of West Virginia and west-central Virginia, resulting in 23 fatalities and 5 new record river crests. The flash flooding was part of a multiday event that was classified as a billion-dollar disaster. The 23 June 2016 event occurred during real-time operations by two Hydrometeorology Testbed (HMT) experiments. The Flash Flood and Intense Rainfall (FFaIR) experiment focused on the 6–24-h forecast through the utilization of experimental high-resolution deterministic and ensemble numerical weather prediction and hydrologic model guidance. The HMT Multi-Radar Multi-Sensor Hydro (HMT-Hydro) experiment concentrated on the 0–6-h time frame for the prediction and warning of flash floods primarily through the experimental Flooded Locations and Simulated Hydrographs product suite. This study describes the various model guidance, applications, and evaluations from both testbed experiments during the 23 June 2016 flash flood event. Various model outputs provided a significant precipitation signal that increased the confidence of FFaIR experiment participants to issue a high risk for flash flooding for the region between 1800 UTC 23 June and 0000 UTC 24 June. Experimental flash flood warnings issued during the HMT-Hydro experiment for this event improved the probability of detection and resulted in a 63.8% increase in lead time to 84.2 min. Isolated flash floods in Kentucky demonstrated the potential to reduce the warned area. Participants characterized how different model guidance and analysis products influenced the decision-making process and how the experimental products can help shape future national and local flash flood operations.

Significance Statement

Testbed environments allow for researchers to evaluate new products and techniques through structured application and feedback from end-users. Two Hydrometeorology Testbed experiments were operating during the historic flash flood event in the West Virginia region on 23 June 2016. This study investigates how experiment participants applied experimental numerical weather prediction forecasts and hydrologic model guidance in the generation of forecast products and flash flood warnings. Findings from model and product evaluations characterized the various strengths and challenges with predicting a record rainfall event while assessing participant perceptions on how new products influenced flash flood operations. Findings from this event can help shape future operational needs and the movement toward probabilistic information in the forecast and warning process.

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