Analysis of the 15 June 2013 Isolated Extreme Rainfall Event in Springfield, Missouri

An isolated extreme rainfall event occurred across portions of the Springfield, Missouri, area on 15 June 2013, causing substantial flooding of several small headwater tributaries of the James River. Heavy, nearly stationary thunderstorm activity developed along an outflow boundary after 1500 UTC. This area of thunderstorms trained over southern Springfield before dissipating around 1845 UTC. Post-event analysis of rainfall amounts indicated both gauge observations and radar-derived estimates exceeding the 100-yr event (1% annual chance equivalent). Local storm reports from the National Weather Service (NWS) forecast office in Springfield were supplemented with additional reports derived from news media and social media. Flash flood nowcasting techniques such as NWS gridded flash flood guidance (GFFG), rainfall average recurrence interval (ARI) estimates, the distributed hydrologic model-threshold frequency (DHM-TF), and the flooded locations and simulated hydrographs (FLASH) project were compared to local storm reports of flash flooding. A timeline of output from each of these techniques was compared to the time of reported flooding to evaluate the usefulness of each tool in the context of NWS operations. It was found that GFFG underestimated the scope of the flash flooding and would not have provided an estimate of flash flood severity. Rainfall ARI estimates, DHM-TF, and FLASH each suggested a significant flash flood event; however, DHM-TF output would have been available too late for forecasters and FLASH output would have provided several areas of false alarms. Rainfall ARI estimates provided the best balance of detecting areas of flash flooding, correctly estimating flash flood severity, and being available in a timely manner to NWS forecasters.