Isaac, along with Florence, Helene and two other systems increasingly likely to form, have set a hectic pace for the Atlantic - even busier than past year when Harvey, Isaac and Maria made landfall within three weeks of each other.
The storm is expected to produce 3 to 5 inches of rain across Martinique, Dominica, and Guadeloupe, with near 10 inches possible in isolated areas, forecasters said.
"It's just extremely busy and it's even busier than past year and all at once", Blake said.
It is forecast to move north-westwards, passing the Azores Islands on Saturday and heading towards north-western Europe.
"They're all interplaying with one another and it's not a particularly confident scenario", he said.
The centre of Isaac passed between Martinique and Dominica with maximum sustained winds of about 45 miles per hour.
He said the federal government and first responders are ready to assist, but that 'bad things can happen when you're talking about a storm this size'.
If anything, maybe a bit more rain, especially near Naples, will be the most South Florida sees of Isaac, said meteorologist Steven Ippoliti.
Forecasters said Wednesday that Florence's wind field is expanding, making it a large, stable hurricane with a clearly defined eye at its center.
Hurricane Florence Could Bring Up To 30 Inches Of Rain To Carolinas
The centre is slowing down and is expected to stall and perhaps wander around just off shore on Thursday, Friday and Saturday. For information specific to your area, please see products issued by your local National Weather Service forecast office.
"A turn toward the north and northeast with an increase in forward speed is expected during the next few days", according to the agency.
The storm is now around 530 miles southeast of Cape Fear, North Carolina, and is moving west-northwest at 17 mph.
President Donald Trump declared states of emergency for North and SC and Virginia, opening the way for federal aid.
On the current projected track the centre of this system is forecast to pass between 100 and 150 miles (160 to 240 km) north of Barbados early on Thursday morning.
It's a detail that almost got lost among all the wind, rain and storm surge data sent out by the National Hurricane Center on Wednesday. Then on Sunday, as a weakening Florence moves away from our region, our winds will gradually weaken during the day, with some wraparound showers possible.
With the ground already saturated from recent rain, another drenching from Florence combined with winds could easily lead to trees being uprooted and widespread power outages, he said.
Tropical Storm Isaac made its closest approach to St. Croix Thursday night, passing nearly 200 miles to the south and having no apparent impact on the territory as it made its leisurely way across the Caribbean.
A tropical wave in the Gulf of Mexico is still being monitored, but its chance of development in the coming days has decreased.