Update as of 8 AM Wednesday:
Potential Tropical Cyclone Nine is not yet a tropical storm, but squally weather is moving through the Lesser Antilles this morning.
The National Hurricane Center says there is a 90 percent change the potential tropical cyclone will achieve named storm status later today. The forecast track takes the center of the system near or just south of the Virgin Islands and Puerto Rico tonight and near or over the Dominican Republic and Haiti on Thursday. Assuming the storm survives the high terrain of Hispaniola, it may approach Cuba, the Florida Straits and the Florida Peninsula this weekend. Recent forecasts from the National Hurricane Center have expressed considerable uncertainty in the track and strength of the storm this upcoming weekend, owing to the fact that its center has not consolidated and its possible land interaction with Hispaniola. At the least, an increase in showers appears probable for at least South Florida by Saturday, and possibly tropical storm conditions based on the latest official National Weather Service forecasts.
Original article from Tuesday afternoon:
Potential Tropical Cyclone Nine formed Tuesday morning about 500 miles east of the Windward Islands. Uncertainty in the fate of the developing storm is high, but parts of the Sunshine State could be affected by the end of the week.
Potential Tropical Cyclone Nine is likely to strengthen further Tuesday and become a Tropical Storm Tuesday night as it tracks west-northwest toward northern parts of the Lesser Antilles. Tropical Storm Warnings have been issued for the northern Lesser Antilles and Puerto Rico as of Tuesday morning. Heavy rainfall and potentially life-threatening flash flooding and mudslides are anticipated across the northern island chain and parts of the eastern Greater Antilles beginning Wednesday.
The long-range track and intensity forecast for this system remain uncertain at this time given the unorganized structure of the potential cyclone. The majority of weather models agree that this system will likely approach the Windward Islands and take a northerly turn over the eastern Greater Antilles. If the system comes into contact with these larger islands it could help to keep the storm below hurricane strength as it approaches the Sunshine State by Saturday night and overnight into Sunday. There is still the possibility that Potential Tropical Cyclone Nine will remain out at sea and turn before impacting the continental United States, or even dissipate before approaching Florida.
The latest advisory from the National Hurricane Center is expecting this system to maintain tropical storm strength over the next several days as it approaches South Florida. An Air Force Reserve Hurricane Hunter Aircraft is scheduled to investigate the system Tuesday afternoon providing more information on the strength of the Potential Tropical Cyclone Nine.
This system will be given the name "Isaias" once it is deemed a tropical storm by the National Hurricane Center (maximum wind speeds of 39 mph or 62.8 km/h). This would be the earliest ninth named storm on record in the North Atlantic basin. The current record for the earliest "I" named storm was "Irene" on August 7, 2005.