Before a raindrop fell on Friday, some low-lying roads and yards flooded in Coastal Georgia’s marsh-front areas. Along U.S. 80 at the mid-morning’s high tide, the marsh and the Savannah River threatened to converge on this only road in and out of Tybee Island.
In Glynn County, the F.J. Torras Causeway to St. Simons was inundated, said Glynn County Emergency Management Agency Director Josh Bain.
That’s because it was a higher than normal high tide, called a king tide. King tides occur when the moon is full or new and closest to Earth in its elliptical orbit, increasing its gravitational pull on the water. Fall king tides are typically the highest because water is near its warmest and most expanded, pushing up sea level.
The king tide can be pushed even higher by wind and rain, as is expected as the weekend continues.
“We’re looking at an inch to 2 inches of rain,” Bain said Friday. “It’s gonna be a little rough tomorrow. Stay home and read a book.”
The flooding effects of king tides are becoming more frequent as fossil fuel emissions push average temperatures higher, which in turn increases sea levels. These floods are called tidal floods or sunny day floods.
The National Oceanic and Atmospheric Administration recorded 12 days of tidal flooding at the Fort Pulaski tide gauge last year and predicts five to nine days this year. In 2000, the annual average was two. By 2030, it’s expected to climb to 15-25 per year.
Fort Pulaski National Monument delayed its opening Friday and will delay again over the weekend to avoid having visitors drive through a flooded entrance area.
On Tybee, the city tried to document flooding for “climate change verification, funding requests, growth…so many options to provide data when needed or appropriate,” texted Mayor Shirley Sessions.
But Friday’s flooding there was mild, Sessions said.
“It didn’t cross the road, nothing significant,” she texted.
To stave off tidal flooding, U.S. 80 was raised about 8 inches in its lowest spots when the road was repaved in 2018.
With additional king tides plus more rain on the way over the weekend, Tybee officials are still on their guard and in touch with the National Weather Service in Charleston.
“The gale blowing NNE right now is creating variations in the tide models and minor changes in the wind direction can have significant changes to the peak water levels, Sessions texted. “The astronomical prediction is for a 9.05-foot tide at 9:45 a.m. at the Fort Pulaski gauge. The forecast prediction right now is 10.7 feet. Depending on weather conditions at high tide, that could change in either direction. There’s usually a 90-minute window to watch for U.S. 80 flooding, and it’s typically delayed by as much as 30 minutes from the predicted high tide. Regardless, it’s very likely that the road will need to be closed for a brief period due to flooding and removal of any marsh wrack/debris.”
Check these resources for more information about tidal flooding in Georgia:
NOAA provides several resources on coastal flooding, including the NOAA Coastal Inundation Dashboard, which provides real-time water levels with forecasts out to 48 hours for all tidal stations.
NOAA’s high tide flooding report allows comparison of the number of tidal floods each year at each tide gauge. It also provides predictions of the flooding expected in the future. Georgia has only one NOAA tide gauge at Pulaski. The closest gauge to Brunswick is in Fernandina Beach.
The Smart Sea Level Sensor Dashboard maps out its sensors and provides real time data about water levels (and other environmental parameters such as temperature, humidity and barometric pressure) at 60 sites around Chatham County.
The Tide brings regular notes and observations on news and events by The Current staff.