Inherent uncertainty in hurricane forecasts 1 m below MSL), the storm tide would be only 0.5 m above MSL. However, if the storm surge is happening during low tide (e.g. For example, if the storm surge is 1.5 m and predicted high tide is 1m above MSL, the resulting total water level would be 2.5 m above MSL, which means the coastal areas lower than 2.5 m above MSL would be under the potential risk of storm surge flooding. The storm surge with concurrent high tide is usually much more damaging than during low tide condition, so it is very important to model astronomical tide along with storm surge to make a realistic water level prediction during a storm. ![]() In reality, storm surge only makes up a part of what causes water levels to rise along the coast during a hurricane. Storm tide is the total observed seawater level during a storm, resulting from the combination of storm surge and the astronomical tide. Based on NOAA’s definition, storm surge is the abnormal rise in seawater level during a storm, measured as the height of the water above the normal predicted astronomical tide. To set the stage, there are a few definitions and pointers about hurricane predictions we will want to clarify before sharing the results of our model.įirst, it is key to understand what we mean by storm tide and storm surge to interpret our results. The predicted coastal water level shown can be used to drive local inundation models to provide coastal flooding forecast. The predicted potential impacted areas were compared with satellite images in Grand Bahama Island, and the predicted peak water levels were compared with NOAA tidal gauge observations along the U.S. East Coast (see the right panel of GIF below). In this article, we share the results from applying an advanced large-scale hydrodynamic model, SCHISM (Semi-implicit Cross-scale Hydroscience Integrated System Model) with hurricane forecasts as inputs (see left panel of GIF below), during Hurricane Dorian to predict the storm tide, a combination of astronomical tide and storm surge, along the coastlines of the Bahamas and entire U.S. ![]() All results are preliminary and for discussion purposes only. ![]() Note to reader: The model described below is in development by One Concern, as part of the company’s ongoing research into the challenging and increasingly important field of coastal flood modeling. Zhuo Liu, Ph.D., Flood Data Scientist at One Concern, Inc.
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