Former Tropical Depression Twentysix strengthened into Tropical Storm Delta south of Jamaica on Monday morning. At 8:00 a.m. EDT on Monday the center of Tropical Storm Delta was located at latitude 16.4°N and longitude 78.4°W which put it about 65 miles east of the Mouth of the Mississippi River and about 130 miles south of Negril, Jamaica. Delta was moving toward the west-northwest at 9 m.p.h. The maximum sustained wind speed was 40 m.p.h. The minimum surface pressure was 1004 mb.
A Hurricane Watch was in effect for the Isle of Youth, Pinar del Rio and Artemisa, Cuba. A Tropical Storm Warning was in effect for the Cayman Islands. A Tropical Storm Watch was in effect for La Habana, Cuba.
More thunderstorms developed near the center of former Tropical Depression Twentysix on Monday morning and the National Hurricane Center upgraded the system to Tropical Storm Delta. The circulation around Tropical Storm Delta was still organizing. Bands of showers and thunderstorms were revolving around the center of Delta. The strongest rainbands were in the southern half of the circulation. Storms near the center were generating upper level divergence which was pumping mass away from the tropical storm. The removal of mass allowed the pressure to decrease, which caused the wind speed to increase.
Tropical Storm Delta will move through an environment which will be very favorable for intensification. Delta will move over water where the Sea Surface Temperature is near 30˚C. It will move under an upper level ridge where the winds are weak. There will be little vertical wind shear. Tropical Storm Delta will intensify and it could strengthen into a hurricane by Tuesday night. Once an inner core with an eye and an eyewall develops, Delta could intensify rapidly. There is a chance Tropical Storm Delta could strengthen into a major hurricane.
Tropical Storm Delta will move around the western end of a subtropical high pressure system over the western Atlantic Ocean. The high will steer Delta toward the northwest during the next few days. On its anticipated track Tropical Storm Delta could reach the Cayman Islands on Monday night. Delta could be near the western end of Cuba by Tuesday night and it is likely to be a hurricane at that time. Delta could approach the central Gulf Coast on Thursday night. It could be a major hurricane when it approaches the Gulf Coast.
Elsewhere, Tropical Storm Gamma weakened as it meandered north of the Yucatan Peninsula. Strong southerly winds in the upper levels blew the top off of Tropical Storm Gamma on Sunday night. At 8:00 a.m. EDT on Monday the center of Tropical Storm Gamma was located at latitude 22.6°N and longitude 87.5°W which put it about 165 miles (270 km) east-northeast of Progreso, Mexico. Gamma was moving toward the south-southwest at 2 m.p.h. (3 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 1001 mb.
A Tropical Storm Warning was in effect for the portion of the coast from Cancun to Dzilam, Mexico. A Tropical Storm Watch was in effect for the portion of the coat from Dzilam to Campeche, Mexico.