"Gradual weakening is forecast over the next couple of days, and Helene is expected to become a tropical storm on Thursday". This rainfall may cause unsafe flash flooding.
With predicted rainfall measured in feet not inches, forecasters say people living along creeks and rivers in the Carolinas should move to higher ground well ahead of the storm's arrival.
Thousands of residents in North and SC have fled their homes as Hurricane Florence, the biggest of the extreme weather conditions on the map, looks set to tear its way through the eastern seaboard. When Isaac reaches the west-central Caribbean Sea in a couple of days, the shear may relax somewhat and the global models suggest that there will be an increase in mid-level moisture.
Helene is a Category 2 storm that's even farther off the coast than both of the other storms, but it's not expected to ever make landfall.
Tornadoes: Tornadoes will be possible along and to the right of the track of Florence, especially in South Carolina, Saturday & Sunday.
"The deepest water will occur along the immediate coast in areas of onshore winds, where the surge will be accompanied by large and destructive waves", the NHC said.
"We can not stress this enough, Florence poses a very serious threat to people who live far away from the coast", said a National Weather Service tweet late Tuesday.
Winds of 40 mph extend outward up to 80 miles (130 km) from the center, mainly to the northwest. Strengthening is forecast through Wednesday. Multiple states have already declared a state of emergency in preparation for the damaging flooding that Florence is likely to bring.
It was a potentially catastrophic Category 4 storm but was expected to keep drawing energy from the warm water and intensify to near Category 5, which means winds of 157 miles per hour (253 kph) or higher. The storm is moving toward the southwest near 6 miles per hour (9 km/h).
Hong Kong and Macau are expected to be ripped through by the storm, according to the latest trajectory through the Western Pacific.
The GOES-East weather satellite, which keeps a constant eye on the East Coast and the Atlantic, has captured some breathtaking images of Hurricane Florence, Tropical Storm Isaac and Hurricane Helene approaching the Americas (in that order).