Update as of 9:30 AM Sunday
Tropical Storm Warnings are in effect from South Santee River southward, including Charleston, Beaufort, and Hilton Head Island ahead of the likely arrival of Tropical Storm Isaias. Tropical Storm Watches are now posted for the Grand Strand.
Isaias is now a tropical storm and has top sustained winds of 65 mph as of the mid-morning Sunday advisory. The center of the storm is forecast to be near the Lowcountry coast late Monday afternoon, and near the Grand Strand coast late Monday evening. It is possible the storm may come ashore anywhere along the South Carolina coast.
Regardless of the exact track, conditions are expected to deteriorate from Hilton Head to Charleston on Monday morning, with tropical storm conditions likely arriving Monday afternoon. Tropical storm conditions are likely to arrive in the Grand Strand and portions of the Pee Dee early Monday evening. Tropical storm force winds are also likely inland, particularly along and east of I-95.
Storm Surge Watches are in effect from Edisto Beach northward, where water may be 2 to 4 feet above normally dry ground somewhere within the watch area, particularly near the times of high tide. The tide cycle with the greatest risk of storm surge would be Monday evening’s cycle.
Rainfall amounts of 4 to 6 inches are expected from Charleston northward toward Georgetown, Myrtle Beach, and Conway. 2 to 4 inches are possible farther inland toward Interstate 95 in the Lowcountry and Pee Dee. For this reason, Flash Flood Watches are in effect for the Charleston area northward to the Grand Strand, Pee Dee, and as far west as Orangeburg, Sumter, and Chesterfield counties. Currently, the Santee River near Jamestown is forecast to experience minor flooding based on the Sunday morning river forecast, but other rivers, streams, and roads are likely to flood if these rainfall amounts are realized.
Conditions are expected to improve statewide by Tuesday morning as Isaias heads toward the Mid Atlantic and Northeast U.S. coastline.
Original story as of 6 PM Saturday: A Tropical Storm Watch has been issued for the coastlines of South Carolina northward to South Santee River ahead of Isaías. Isaías was downgraded to a Tropical Storm as of the latest advisory from the National Hurricane Center with maximum sustained winds of 70 mph. Isaías has a good chance restrengthen back into a Category 1 hurricane overnight Saturday as it approaches the southeast coast of Florida. The latest forecast from the National Hurricane Center shows Isaias maintaining hurricane intensity as it nears Florida, The latest forecast from the National Hurricane Center expects Isaías to weaken, again, back to a tropical storm as it approaches South Carolina because of the unfavorable environment ahead of it. If Isaías moves close enough to the coastline it has the potential to bring tropical storm-force winds to areas near Hilton Head, Beaufort and Charleston beginning Monday morning. Northern coastlines near Myrtle Beach may begin to see tropical storm-force winds Monday afternoon or evening based on the latest forecast. The National Hurricane Center warned in its latest advisory that high surf and rip currents are expected to arrive ahead of the storm along with two to four inches of rain, with local amounts as high as six inches, and minor river flooding. Forecast models are suggesting that the Lowcountry, Pee Dee and Grand Strand are the most likely areas to feel effects from Isaías on Monday. Fewer or no impacts are anticipated over the Midlands and particularly the Upstate if the latest forecasts hold. Conditions are likely to improve late Monday night or Tuesday in eastern South Carolina as Isaías moves northward toward the Mid-Atlantic and Northeastern United States.