The Frogmore Metroplex (Coastal Georgia and the South Carolina Lowcountry) are looking at some coastal hazards this weekend as strong onshore winds will be ganging up with high astronomical tides (full moon plus with a month of equinox). The local National Weather Service office (located in Charleston SC so as not to be distracted by being too close to the Center of All The Things) has issued a briefing on the subject. TL;DR: going to be windy the next 2-3 days, with higher than normal tides and coastal flooding in all the usual places. Be watchful for road closures (like US 80 on the way to Tybee), and may not be the best idea to be out on the water in a smallish boat. And be ready to clean up a bunch of leaves next week (or leave them out so the Trick or Treaters can play in them!)
Here’s the details: A high to the north and a low to the south will cause a jet of air to flow westward right into the GA/SC coast …
Here is a three day animation of surface pressure and winds:
This means it will be gusty all along the coast, and the local waters will be pretty rough this weekend with gale-force winds, so you might want to reconsider being out on the water. Be careful crossing bridges, especially the higher ones, if driving high profile vehicles.
This also means is that the wind will be blowing water into the coast, and it won’t be able to drain out as much at low tide so the tide cycles will build on one another. It is likely there will be coastal flooding around the times of high tides through Monday. Here’s the warning matrix as of the moment:
The current forecast at Fort Pulaski shows it flirting with “Major Flood Stage:”
As a reminder of what happens at the various flood levels, that means:
At 10.5 ft MLLW, major coastal flooding occurs. Damaging flooding is expected, expanding along the entire southeast Georgia coast. Flooding will likely cause the closure of HW-80, isolating residents on Tybee Island. Several other island communities will also likely become isolated due to flooded and impassable roadways. On Tybee Island, widespread significant flooding is expected with numerous properties impacted.
10.4 – Peak tide level reached in association with an unnamed hurricane that made landfall near Hilton Head Island, SC as a Category 2 hurricane on August 11th, 1940.
10.02 – Peak tide level reached in association with Tropical Storm Gabrielle as it moved away from the Southeast coast on September 16th, 2001.
10 – At 10.0 ft MLLW, moderate coastal flooding occurs. Shipyard Rd will be impassable, isolating residents on Burnside Island. Water will start to encroach on HW-80 and as the tide gets closer to 10.5 ft MLLW, could begin to cover portions of the roadway. Flooding will expand on Tybee Island and Catalina Dr and Lewis Ave will be impassable. Flooding will also impact Wilmington Island, the Coffee Bluff community, Ossabaw Island, Sapelo Island, and portions of HW-17 south of Darien.
9.5 – At 9.5 ft MLLW, minor coastal flooding occurs. Flooding will begin to impact Shipyard Road to Burnside Island. Parts of Ft Pulaski National Monument will begin to flood, including several trails. Flooding will also begin to impact Tybee Island including Catalina Dr and Lewis Ave. In Bryan County, water could breach docks near Ft McAllister and flooding will impact portions of Mill Hill Rd. In Liberty County, flooding impacts the Halfmoon Landing area and Cattle Hammock Rd near Bermuda Bluff subdivision.
Again, this is a coastal event – nobody inland (off the marshes or tidal creeks) needs to worry about flooding, just some gusty winds (below damage levels).
In summary, here are their “Key Messages:”
