Tag Archives: Potential Tropical Cyclone Eighteen

Tropical Storm Warning Issued for Jamaica, Hurricane Watch for Cayman Islands

The threat posed by a low pressure system over the Southwestern Caribbean Sea prompted the issuance of a Tropical Storm Warning for Jamaica and a Hurricane Watch for the Cayman Islands on Sunday afternoon.  The low pressure system was designated as Potential Tropical Cyclone Eighteen by the U.S. National Hurricane Center.  At 4:00 p.m. EST on Sunday the center of Potential Tropical Cyclone Eighteen was located at latitude 13.0°N and longitude 77.1°W which put the center about 345 miles (555 km) south of Kingston, Jamaica.  The low pressure system was moving toward the northeast at 7 m.p.h. (11 km/h).  The maximum sustained wind speed was 35 m.p.h. (55 km/h) and there were wind gusts to 45 m.p.h. (75 km/h).  The minimum surface pressure was 1004 mb.

A Hurricane Watch is in effect for Grand Cayman, Little Cayman, and Cayman Brac.

A Tropical Storm Warning is in effect for Jamaica.

A U.S. Air Force Reserve Hurricane Hunter aircraft investigated a low pressure system over the Southwestern Caribbean Sea on Sunday afternoon.  The aircraft found that there was a distinct low low level center of circulation in the low pressure system.  More thunderstorms were forming near the center of the low pressure system.  Bands of showers and thunderstorms were starting to revolve around the center of Potential Tropical Cyclone Eighteen.  Storms near the center of the low pressure system began to generate upper level divergence.

Potential Tropical Cyclone Eighteen will move through an environment favorable for intensification during the next 24 hours.  The low pressure system will move over water where the Sea Surface Temperatures are near 29°C.  It will move under the western end of an upper level ridge over the Caribbean Sea.  The upper level ridge will produce southeasterly winds that will blow toward the top of the low pressure system.  Those winds will cause some vertical wind shear, but the wind shear will not be enough to prevent intensification.  Potential Tropical Cyclone Eighteen will intensify during the next 24 hours.  It is likely to become a tropical storm on Monday.

Potential Tropical Cyclone Eighteen will move around the southwestern part of a high pressure system over the western Atlantic Ocean.  The high pressure system will steer Potential Tropical Cyclone Eighteen toward the north-northwest during the next 24 hours.  On its anticipated track, Potential Tropical Cyclone Eighteen will reach Jamaica on Monday night.  It could reach the Cayman Islands on Tuesday afternoon.

Potential Tropical Cyclone Eighteen will bring strong winds and heavy rain Jamaica and the Cayman Islands.  Heavy rain is likely to cause floods in some locations.

Elsewhere, Subtropical Storm Patty moved east of the Azores.  At 4:00 p.m. EST on Sunday the center of Subtropical Storm Patty was located at latitude 37.3°N and longitude 22.3°W which put the center about 280 miles (450 km) east-southeast of Lajes, Azores.  Patty was moving toward the east at 17 m.p.h. (28 km/h).  The maximum sustained wind speed was 45 m.p.h. (75 km/h) and there were wind gusts to 60 m.p.h. (95 km/h).  The minimum surface pressure was 990 mb.

Potential Tropical Cyclone Eighteen Prompts Warnings for Cuba and Bahamas

Potential Tropical Cyclone Eighteen prompted the governments of Cuba and the Bahamas to issue Tropical Storm Warnings and Watches for portions of those countries on Friday afternoon.  At 5:00 p.m. EDT on Friday the center of Potential Tropical Cyclone Eighteen was located at latitude 17.5°N and longitude 84.5°W which put it about 415 miles (670 km) south-southwest of Havana, Cuba.  It was moving toward the north-northwest at 6 m.p.h. (10 km/h).  The maximum sustained wind speed was 40 m.p.h. (65 km/h) and there were wind gusts to 50 m.p.h. (80 km/h).  The minimum surface pressure was 1006 mb.

Tropical Storm Warnings were issued for the Cuban provinces of Isla de la Juventud, La Habana, Ciudad de la Habana, Matanzas, Cienfuegos, and Villa Clara.  Tropical Storm Warnings were also issued for the northwestern Bahamas including the Abacos, Andros Island, Berry Island, Bimini, Eleuthera, Grand Bahama Island and New Providence.  Tropical Storm Watches were issued for the Central Bahamas including Cat Island, the Exumas, Long Island, Rum Cay and San Salvador.

An Air Force Reserve Hurricane Hunter reconnaissance plane investigated the system formerly known as Invest 93L on Friday afternoon.  The plane found sustained winds to tropical storm force.  The plane also found a broad circulation center with several smaller centers of circulation revolving around inside the broader center.  Based on the observations from the plane, the National Hurricane Center (NHC) chose not to upgrade the system to Tropical Storm Philippe in its 5:00 p.m. EDT advisory.  However, NHC did change the designation of the system from Invest 93L to Potential Tropical Cyclone Eighteen.  If a more well defined center of circulation develops, then NHC could still change designation of the system to Tropical Storm Philippe.

The circulation of Potential Tropical Cyclone Eighteen is still organizing.  As mentioned above, there is a broad center of counterclockwise rotation.  There are also several smaller counterclockwise swirls within the broader center.  More showers and thunderstorms developed closer to the center of circulation on Friday afternoon.  The storms closer to the center of circulation were generating some upper level divergence which was pumping away mass to the northeast of the system.  Some bands of showers and thunderstorms were developing in the outer portions of the circulation.

Potential Tropical Cyclone Eighteen will move through an environment somewhat favorable for intensification.  It will move over water where the Sea Surface Temperature is near 30°C.  The system is embedded in a flow over warm moist air.  However there is a stationary front northwest of the system and there is cooler, drier air north of the stationary front.  The system is currently under the western side of an upper level ridge.  The upper level winds are weak and there is not much vertical wind shear.  Potential Tropical Cyclone Eighteen could slowly intensify during the next 24 hours as the circulation becomes more well organized.

The ridge east of Potential Tropical Cyclone Eighteen is steering the system toward the north-northwest.  That general motion should continue for another six to twelve hours.  An upper level trough will approach the system from the west on Saturday and the trough will start to steer it more toward the northeast.  On its anticipated track Potential Tropical Cyclone Eighteen will approach Cuba on Saturday afternoon.  The center of the system will move south of the Florida Keys on Saturday night and it could move across the northwestern Bahamas on Sunday.

The system will bring gusty winds and locally heavy rain to those locations.  The locally heavy rain could cause flooding.  There could be a storm surge of several feet (one to two meters) on parts of the south coast of Cuba, where the wind blows the water toward the coast.  There could also be some storm surge along the coasts of the Florida Keys.