USGS coastal change forecasts provide vital information during coastal storms that can help emergency management officials decide which areas to evacuate, where and when to close coastal roads and where to position clean-up equipment in advance of a storm.

The National Hurricane Center is currently forecasting Nicole will make landfall in Florida November 10 as a hurricane. The NHC is also warning of potentially dangerous storm surge along parts of Florida’s Gulf and Atlantic coasts and portions of coastal Georgia.

“One of the challenges creating this coastal change forecast is that we haven’t fully assessed the significant coastal change brought just more than a month ago from Hurricane Ian,” said Kara Doran, a USGS oceanographer and leader of the USGS Coastal Change Hazards Storm Team. “We know Ian caused significant coastal change and likely made the coasts more vulnerable. But, we don’t have updated measurements on how much Ian lowered dune heights so the coastal change Nicole causes may be more significant than what we forecast.” 

USGS coastal change experts are forecasting Nicole’s waves and surge are likely to cause 42% of the dunes along Florida’s west coast from Bonita Beach to Anclote Key and from Panacea to Mexico Beach to experience some erosion. It’s projected that 81% of the dunes along Florida’s east coast from Miami to the Georgia line will endure some level of erosion. Seventy-seven percent of Georgia’s dunes and 55% of South Carolina’s dunes from the Georgia state line to South Island are also forecast to face some level of erosion.

A more severe level of coastal damage known as overwash occurs when water levels reach higher than the top of dunes. When a beach is overwashed, sand can be pushed and deposited inland, causing significant changes to coastal landscapes and blocking roadways. Overwash can reduce the height of protective sand dunes, alter beach profiles and leave areas behind the dunes more vulnerable to future storms.

Approximately 10% of Florida’s dunes along sandy beaches from Bonita Beach to Anclote Key and from Panacea to Mexico Beach could be overwashed. On Florida’s east coast from Miami to the Georgia state line, 11% of the dunes are forecast to be overwashed. In Georgia, 15% of the dunes are predicted to be overwashed and in South Carolina, 19% of the dunes from the Georgia state line to South Island could be overwashed.  

The most severe level of coastal change is when dunes are inundated - meaning continuously covered by ocean water. This storm effect can cause flooding behind dunes that may impact coastal communities. Currently, only 2% of Florida’s west coast dunes and 1% of South Carolinas dunes along sandy beaches are forecast to be inundated.

The most current forecast is always available on the USGS Coastal Change Hazards Portal. Real-time coastal change forecasts for individual locations along the coast are also available in the Total Water Level and Coastal Change Forecast Viewer.

The forecast of Nicole’s coastal effects at landfall is based on results of the USGS Coastal Change Forecast model, which has been in use since 2011 and is continually being improved. The model starts with inputs from the NHC’s storm surge predictions and National Oceanic and Atmospheric Administration wave forecast models. It then adds detailed information about the expected landfall region’s beach slope and dune height. The predictions define “very likely” effects as those that have at least a 90% chance of taking place, based on the storm’s forecast track and intensity. 

As the USGS continues to take all appropriate preparedness actions in response to Nicole, those in the storm’s projected path can visit Ready.gov for tips on creating emergency plans and putting together an emergency supply kit.

Learn more about USGS hurricane science.