Mesoanalysis-Driven Message Modification for the May 8-9, 2024 Tornado Outbreak

Forecasting and messaging for severe weather events can be incredibly challenging for even the most seasoned meteorologists. New environmental information, such as additional model runs, surface observations, balloon launches, and SPC outlooks, are almost constantly flowing. This leads to a continual process of refining forecasts and messaging to ensure partners and the public take appropriate actions. This fact held true during the May 8-9, 2024 tornado outbreak, with 20 tornadoes in the National Weather Service Huntsville office’s area of responsibility. Twelve supercells produced thirteen tornadoes in the evening hours with an overnight quasi-linear convective system (QLCS) that produced seven.

The office had to pivot from the original briefing information, which advertised an overnight quasi-linear convective system (QLCS) with an elevated tornado and damaging wind threat as the sole weather impact. In reality, twelve supercells erupted over the area in the evening hours before the QLCS arrived.

This presentation will discuss the 24-hour period before the event, where the office went through careful mesoanalysis to adjust from only messaging the nocturnal QLCS to indicating a low-probability high-impact round of storms in the afternoon and evening hours. The initial recognition began in sounding analysis, representing an environment conditionally favorable for high-end severe weather if there was a lifting mechanism. It was not until 24 hours before the event that convection-allowing models began indicating outflow boundaries that would provide forcing for ascent that would lead to supercellular convection. Tying this mesoanalysis to external messaging led to partners not being caught off guard by the numerous supercells and significant (>EF2) tornadoes. Examples from the day-of partner webinar, situation report, and social media and Slack posts will demonstrate how frequent updates in a 24-hour period empowered and prepared partners and the public ahead of this high-impact weather event.