Tropical Storm Fiona Moves Closer to Puerto Rico

Tropical Storm Fiona moved closer to Puerto Rico on Saturday night. At 11:00 p.m. EDT on Saturday the center of Tropical Storm Fiona was located at latitude 16.6°N and longitude 64.9°W which put it about 75 miles (120 km) south of St. Croix. Fiona was moving toward the west-northwest at 8 m.p.h. (13 km/h). The maximum sustained wind speed was 60 m.p.h. (95 km/h) and there were wind gusts to 75 m.p.h. (120 km/h). The minimum surface pressure was 997 mb.

A Hurricane Warning was in effect for Puerto Rico, Culebra and Vieques. A Hurricane Warning was also in effect for the portion of the coast from Cabo Caucedo to Cabo Frances Viejo, Domincan Republic. A Hurricane Watch was in effect for the U.S. Virgin Islands. A Hurricane Watch was also in effect for the portion of the coast from Cabo Frances Viejo to Puerto Plata, Dominican Republic. Tropical Storm Warnings were in effect for the U.S. Virgin Islands, the British Virgin Islands, and the portion of the coast from Cabo Frances Viejo to Puerto Plata, Dominican Republic. A Tropical Storm Watch was in effect for the portion of the coast from Cabo Caucedo to Barahona, Dominican Republic.

Tropical Storm Fiona was gradually getting better organized on Saturday night. The inner end of a rainband wrapped around the northern side of the center of circulation. Radar on Puerto Rico showed that an eye could be forming at the center of Fiona’s circulation. Storms near the center generated more upper level divergence that pumped mass away from the tropical storm. The removal of mass was allowing the surface pressure to slowly decrease. Winds to tropical storm force extended out 140 miles (220 km) from the center of Tropical Storm Fiona.

Tropical Storm Fiona will move through an environment somewhat favorable for intensification during the next 24 hours. Fiona will move over water where the Sea Surface Temperatures are near 29˚C. An upper level ridge over the tropical Atlantic Ocean will produce southwesterly winds that will blow toward the top of Tropical Storm Fiona. Those winds will cause some vertical wind shear. The wind shear will inhibit intensification. Tropical Storm Fiona could continue to strengthen gradually, but the wind shear will likely limit intensification during the next 24 hours.

Tropical Storm Fiona will move around the southwestern side of the subtropical high pressure system over the Atlantic Ocean. The high pressure system will steer Fiona toward the west-northwest during the next 24 hours. On its anticipated track the center of Tropical Storm Fiona will be near the southwestern part of Puerto Rico by Sunday evening. Bands in the eastern and northern sides of Fiona’s circulation will bring gusty winds and locally heavy rain to Puerto Rico, the U.S. Virgin Islands and the British Virgin Islands on Sunday. Fiona could begin to affect the eastern part of the Dominican Republic during Sunday night.