The U.S. National Hurricane Center (NHC) said Helene has 90 miles per hour winds, meaning it is a Category 1 storm.
"A life-threatening storm surge is highly likely along portions of the coastline of SC and North Carolina, and a Storm Surge Warning is in effect for a portion of this area", the National Hurricane Center said Wednesday.
In contrast, no coastal watches or warnings were in effect for Helene, but residents of the Azores were encouraged to monitor the storm. This general motion is forecast to continue today with a decrease in forward speed as it gets over the Caribbean Sea.
The mammoth waves were spotted early Wednesday in the storm's northeast quadrant, said the NHC's Tropical Analysis and Forecast Branch, which has been documenting Florence's waves all week.More news: De Bruyne has £223m release clause, reveals Guardiola
Helene, which has been downgraded from a hurricane, is among a glut of tropical storms brewing in the region, with mass evacuations under way in southern USA states as Hurricane Florence barrels across Virginia and the Carolinas. Tropical storm conditions are possible within the tropical storm watch area on Thursday. "Interests elsewhere in the Leeward Islands should monitor the progress of Isaac".
Rain projections also increased, with some locations along the North Carolina coast now expected to get up to 40 inches. It is moving northwest at 15 miles per hour, according to the NHC's update at 11 a.m. Sept 12.
The National Hurricane Center said that the storm is Category 4 in strength.
However, according to the latest projections, the storm might shift slightly to the south and affect Georgia with heavy rain and possible flooding.More news: Bezos: Amazon HQ2 decision will be made by end of the year
It's unclear whether Isaac could reach the US mainland.
Isaac was a hurricane Sunday night but downgraded when maximum sustained winds fell below 74 miles per hour.
The agency is also monitoring a tropical disturbance that has a 60 percent chance of forming a tropical storm. He added: "There's a lot of uncertainty around the developments of that low pressure system".More news: Sick Southern Resident orca hasn't been seen for 'several days'