Radar on the Move: How Forecasters Beat the Odds and Kept the Public Safe

Southeastern Louisiana and southern Mississippi experience a wide range of severe weather hazards throughout the year, including severe thunderstorms, tornadoes, waterspouts, and tropical cyclones. The Slidell, Louisiana National Weather Service WSR-88D Doppler weather radar (KLIX) had served the local community since the NEXRAD modernization phase in 1994. The radar is essential for forecasters to analyze and monitor thunderstorms, providing accurate and timely warnings to the public. The radar’s previous location provided suboptimal coverage in certain areas, including the densely populated metropolitan Baton Rouge area. The doppler radar was relocated to Hammond, Louisiana (KHDC) and upgraded to include a lower elevation scanning angle of 0.3 degrees, addressing the prior limitations and enhancing overall coverage across the area.

The radar relocation project presented a significant challenge for forecasters, who had to provide life-saving warnings without the availability of KLIX radar for an extended period from late November 2023 through mid March 2024. To ensure the NWS could maintain its mission of protecting life and property with timely and accurate warnings during the relocation project, operational staff underwent extensive case-specific training. This training focused on utilizing neighboring WSR-88D radars and alternative observational data sources to monitor storms and anticipate convective evolution accurately through environmental assessment.

Warning verification metrics, including Probability of Detection (POD), False Alarm Rate (FAR), Critical Success Index (CSI), and Lead Time (LT) during the radar outage were compared to performance statistics from prior years since 2007 for both the entire calendar year and the November 27 to March 23 period to assess the impacts that the radar outage had on local warning performance. Our findings did not indicate a significant degradation of warning skill during the outage period, despite forecasters lacking access to a local WSR-88D radar that could provide storm surveillance in the low levels. In fact, the majority of evaluated performance metrics demonstrated above-average warning performance, particularly for Severe Thunderstorm Warnings (SVR) and Flash Flood Warnings (FFW) , compared to previous years. For example, the office’s CSI for SVRs issued during the radar outage was 0.25, which would compare higher than all but one calendar year (CSI of 0.29 in 2011). For FFWs, the POD of 0.97 and average LT of 61.4 minutes during the radar relocation were both better than any historical annual FFW performance score since 2007. These results underscore the effectiveness of the implemented mitigation strategies, including a tailored operational training that renewed emphasis on maximizing situational awareness through mesoanalysis and increased utilization of remote sensing products and other observational tools.