1. The system is expected to become a tropical storm and bring tropical-storm-force winds and heavy rainfall to portions of the northwestern Bahamas today and Saturday. Significant storm surge is not expected in the northwest Bahamas from this system. Residents there should follow any advice given by local officials.

2. The system could bring tropical-storm-force winds to portions of the Florida east coast over the weekend. Residents there should monitor the progress of this system and follow any advice given by local officials.

3. Heavy rainfall is possible from Potential Tropical Cyclone Nine across portions of eastern Florida into this weekend, which could produce flash flooding. There is greater uncertainty than usual in heavy rainfall prospects farther north across the Carolinas.

4. Note that forecast uncertainty for these disturbances is generally larger than for tropical cyclones, especially beyond 48-72 hours.

WHAT'S NEW:

A Tropical Storm Watch has been issued from the VolusiaBrevard County line to the FlaglerVolusia County line.

SUMMARY OF ALERTS:

A Tropical Storm Warning is in effect for...
- Northwestern Bahamas excluding Andros Island

A Tropical Storm Watch is in effect for...
- Jupiter Inlet to FlaglerVolusia County line

A Tropical Storm Warning means that tropical storm conditions are expected somewhere within the warning area within 36 hours.

A Tropical Storm Watch means that tropical storm conditions are possible within the watch area, generally within 48 hours. Interests elsewhere along the east coast of Florida should monitor the progress of this system.

Additional watches and warnings may be required for portions of this area later today. For storm information specific to your area in the United States, including possible inland watches and warnings, please monitor products issued by your local National Weather Service forecast office. For storm information specific to your area outside of the United States, please monitor products issued by your national meteorological service.

WIND: [TOP] Tropical storm conditions are expected within the warning area in the northwestern Bahamas later today. Tropical storm conditions are possible in the watch area on the Florida peninsula by Saturday or Saturday night.

RAINFALL: [TOP] The potential tropical cyclone is expected to produce total rainfall accumulations through Sunday:

The Bahamas...2 to 4 inches, isolated maximum amounts 6 inches. The U.S. Southeast Coast from central Florida into South Carolina...2 to 4 inches.

STORM SURGE: [TOP] This system is not expected to product significant storm surge in the northwestern Bahamas.

At 500 AM EDT (0900 UTC), the disturbance was centered near latitude 24.6 North, longitude 75.2 West. The system is moving toward the northwest near 6 mph (9 km/h), and this general motion is expected to continue with some increase in forward speed through the weekend. On the forecast track, the system is anticipated to move across the central and northwestern Bahamas today, and along or over the east coast of Florida Saturday and Saturday night.

Maximum sustained winds are near 30 mph (45 km/h) with higher gusts. Some strengthening is forecast during the next 48 hours, and the disturbance is forecast to become a tropical depression or a tropical storm during the next day or so.

Environmental conditions are favorable for a tropical depression or tropical storm to form within the next day or two. * Formation chance through 48 hours...high...80 percent * Formation chance through 5 days...high...90 percent

The estimated minimum central pressure is 1009 mb (29.80 inches).

Satellite imagery and surface observations indicate that the tropical disturbance is currently comprised of a trough elongated from west-southwest to east-northeast, with a vorticity center near a loosely curved convective band at the eastern end of the trough. While the system has become a little better organized since the last advisory, it does not yet have a well-defined circulation center. The initial intensity remains 25 kt based on satellite intensity estimates and earlier scatterometer data.

The disturbance is now moving a little faster, with the initial motion of 315/5. The system is to the south of a low- to mid-level ridge over the southeastern United States, and it is to the east of a mid- to upper-level low over the central Gulf of Mexico. The large-scale models forecast the ridge to shift eastward into the Atlantic during the next 24-48 h, with a weakness developing near the southeastern coast of the United States and the east coast of the Florida peninsula. The track guidance indicates that the disturbance will move generally northwestward for 48 h or so, followed by a turn to the north and eventually to the northeast as the system moves through the weakness in the ridge. There is some spread in the guidance, with the GFS model taking a weaker system into the Florida peninsula while the UKMET and ECMWF models show a stronger cyclone farther offshore. Overall, there has been an eastward shift of the guidance since the previous advisory, especially after 72 h. The new forecast track is thus also nudged a little to the east and now calls for the system to spend less time over the Florida peninsula than previously forecast. The new forecast track is to the left of the center of the guidance envelope and the consensus models, and additional adjustments may be necessary once the circulation center becomes better defined.

The disturbance is currently in an environment of moderate southwesterly shear and upper-level divergence caused by the upper-level low and a shortwave trough extending from the low eastward to the southeastern Bahamas. The shear should gradually diminish during the next couple of days, which should allow the disturbance to develop into a tropical cyclone and intensify. The large-scale models forecast the shear to increase after 72 h as a mid-latitude westerly trough moves through the southeastern United States and approaches the system. The new intensity forecast is similar to the previous forecast through 72 h, then it is stronger than the previous forecast due to the forecast track keeping the system more over water.