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Hurricane Michael (2018) made landfall near Mexico Beach, FL, as a Category 5 hurricane, with gauge‐measured water levels over 4 m. Wind and pressure fields were created by blending a parametric near‐field model with a gridded far‐field model. Winds and modeled water levels were well validated across Michael's large impact a‐ea. A detailed analysis of the coastal surge caused by Michael demonstrates that advection contributed significantly to Michael's highest water levels and the timing of the water level across a large portion of the Michael impact area. A momentum balance in a streamwise‐normal coordinate system demonstrates that the advection contributions due to spatial gradients in the flow are identified with streamwise convergence/expansion of the flow field (Bernoulli acceleration) and curvature in the flow field (centrifugal acceleration). These effects are created by the regional geometry and the storm's wind field and are most likely to affect back barrier water levels and along curved coastlines. These findings provide an improved understanding of the role of advection in determining storm surge and, thus, the importance of including it in storm surge models. Plain Language Summary: In 2018, Hurricane Michael hit Mexico Beach, FL, as a Category 5 hurricane, with peak water levels over 4 m. Michael's flooding was studied using computational models that simulated the storm's water levels and currents. These models revealed the influence of the storm's wind patterns and regional geography on water levels and their distribution across the impacted region, particularly emphasizing the flow velocity field surrounding Mexico Beach and the inlet to St. Joseph Bay. Such insights clarify the role of specific flow dynamics and highlight the importance of capturing them accurately in numerical simulations of storm‐induced water surge. Key Points: Advection substantially enhanced Michael's storm surge across a large portion of the Michael impact areaCentrifugal acceleration from flow curvature was the main advection process affecting water levels along the coast during Hurricane MichaelBernoulli acceleration plays an important role back‐barrier in water levels where flow contractions/expansions are present [ABSTRACT FROM AUTHOR]

Predictions of storm surge and flooding require models with higher resolution of coastal regions, to describe fine-scale bathymetric and topographic variations, natural and artificial channels, flow features, and barriers. However, models for real-time forecasting often use a lower resolution to improve efficiency. There is a need to understand how resolution of inland regions can translate to predictive accuracy, but previous studies have not considered differences between models that both represent conveyance into floodplains and are intended to be used in real time. In this study, the effects of model resolution and coverage are explored using comparisons between forecast-ready and production-grade models that both represent floodplains along the US southeast coast, but with typical resolutions in coastal regions of 400 and 50 m, respectively. For two storms that impacted the US southeast coast, it is shown that, although the overall error statistics are similar between simulations on the two meshes, the production-grade model allowed a greater conveyance into inland regions, which improved the tide and surge signals in small channels and increased the inundation volumes between 40% and 60%. Its extended coverage also removed water level errors of 20–40 cm associated with boundary effects in smaller regional models. [ABSTRACT FROM AUTHOR]