| Track: http://www.nhc.noaa.gov/refresh/graphics_at3+shtml/?cone#contents Floater: http://www.ssd.noaa.gov/PS/TROP/floaters.html Potential Tropical Cyclone Eighteen Advisory Number 1 NWS National Hurricane Center Miami FL AL182017 500 PM EDT Fri Oct 27 2017 ...TROPICAL STORM WARNINGS ISSUED FOR WESTERN CUBA AND THE NORTHWESTERN BAHAMAS... SUMMARY OF 500 PM EDT...2100 UTC...INFORMATION ---------------------------------------------- LOCATION...17.5N 84.5W ABOUT 305 MI...490 KM SSW OF THE ISLE OF YOUTH ABOUT 415 MI...670 KM SSW OF HAVANA CUBA MAXIMUM SUSTAINED WINDS...40 MPH...65 KM/H PRESENT MOVEMENT...NNW OR 330 DEGREES AT 6 MPH...9 KM/H MINIMUM CENTRAL PRESSURE...1006 MB...29.71 INCHES WATCHES AND WARNINGS -------------------- CHANGES WITH THIS ADVISORY: The government of Cuba has issued a Tropical Storm Warning for the Cuban provinces of Isla de la Juventud, La Habana, Ciudad de la Habana, Matanzas, Cienfuegos, and Villa Clara. The government of the Bahamas has issued a Tropical Storm Warning for the northwestern Bahamas, including the Abacos, Andros Island, Berry Islands, Bimini, Eleuthera, Grand Bahama Island, and New Providence. The government of the Bahamas has issued a Tropical Storm Watch for the central Bahamas, including Cat Island, the Exumas, Long Island, Rum Cay, and San Salvador. SUMMARY OF WATCHES AND WARNINGS IN EFFECT: A Tropical Storm Warning is in effect for... * Isla de la Juventud, La Habana, Ciudad de la Habana, Matanzas, Cienfuegos, and Villa Clara * Northwestern Bahamas A Tropical Storm Watch is in effect for... * Central Bahamas 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, in this case within 36 hours. Interests in the Cayman Islands, South Florida, and the Florida Keys should monitor the progress of this system. DISCUSSION AND 48-HOUR OUTLOOK ------------------------------ At 500 PM EDT (2100 UTC), the disturbance was centered near latitude 17.5 North, longitude 84.5 West. The system is moving toward the north-northwest near 6 mph (9 km/h). A faster northward motion is expected to begin tonight, followed by a faster motion toward the northeast on Saturday and Sunday. On the forecast track, the system will move across western Cuba late Saturday and move through the northwestern Bahamas Saturday night and early Sunday. Data from an Air Force Reserve Hurricane Hunter aircraft indicate that maximum sustained winds are near 40 mph (65 km/h) with higher gusts. Some strengthening is forecast during the next 24 to 36 hours. Environmental conditions are expected to be conducive for development, and the system is likely to become a tropical storm tonight or Saturday. * Formation chance through 48 hours...high...80 percent * Formation chance through 5 days...high...80 percent Tropical-storm-force winds extend outward up to 80 miles (130 km), mainly to the south of the center. The estimated minimum central pressure based on data from the aircraft is 1006 mb (29.71 inches). HAZARDS AFFECTING LAND ---------------------- RAINFALL: The system has the potential to produce the following rainfall totals: Northern Honduras: Additional 1 to 3 inches through Friday night. Cayman Islands, western and central Cuba and northwestern Bahamas: 4 to 8 inches with maximum totals of 10 inches. These rainfall amounts may produce life threatening flash floods and mudslides. South Florida including the Florida Keys: 3 to 5 inches, isolated maximum of 8 inches possible. These rainfall totals may produce flash flooding, especially in urbanized areas. WIND: Tropical storm conditions are expected to first reach the warning area in Cuba Saturday and the northwestern Bahamas Saturday night. NEXT ADVISORY ------------- Next intermediate advisory at 800 PM EDT. Next complete advisory at 1100 PM EDT. $$ Forecaster Brennan Potential Tropical Cyclone Eighteen Discussion Number 1 NWS National Hurricane Center Miami FL AL182017 500 PM EDT Fri Oct 27 2017 Data from an Air Force Reserve Hurricane Hunter aircraft investigating the disturbance over the northwestern Caribbean Sea indicate that the system does not yet have a well-defined center. In fact, the aircraft data and satellite imagery suggest that there are multiple circulations embedded within a broader circulation at this time. Given the lack of a well-defined center, the system is not a tropical cyclone, but since tropical storm conditions are expected to affect Cuba and the northwestern Bahamas in the next 24 to 36 hours, advisories are being initiated on the system as a potential tropical cyclone at this time. The initial intensity is set to 35 kt based on aircraft data, with these winds found well south of the broad circulation center. However, NOAA buoy 42057 also reported a peak 1-minute wind of 31 kt earlier today. Aircraft data suggest that the central pressure is around 1006 mb. The system is situated in a low-shear environment and over warm waters, so some slow strengthening is expected in the first 24 hours before the system reaches Cuba. The official forecast follows the trend of the intensity consensus in showing a peak of around 45 kt at 36 and 48 hours before the system is absorbed by an approaching cold front in 60-72 hours. Given the lack of a well-defined center, the initial position is and the initial motion of 330/05 are highly uncertain. A faster northward motion should begin soon as the disturbance begins to recurve ahead of an approaching mid/upper-level trough moving into the southeastern United States. This trough should cause a faster northeastward acceleration at 24 through 48 hours. The track model guidance is in generally good agreement on the overall scenario, with more along than cross track spread. The NHC forecast leans toward a blend of the ECMWF and GFS models and is a little slower than the current multi-model consensus. Not surprisingly, given the disorganized initial state of the system, the track forecast uncertainty is larger than usual. FORECAST POSITIONS AND MAX WINDS INIT 27/2100Z 17.5N 84.5W 35 KT 40 MPH...POTENTIAL TROP CYCLONE 12H 28/0600Z 19.1N 84.1W 35 KT 40 MPH...TROPICAL STORM 24H 28/1800Z 21.7N 82.4W 40 KT 45 MPH 36H 29/0600Z 24.6N 79.6W 45 KT 50 MPH 48H 29/1800Z 28.0N 75.5W 45 KT 50 MPH 72H 30/1800Z...ABSORBED $$ Forecaster Brennan |