A broad area of low pressure over the southern Gulf of Mexico became more organized on Sunday and a U.S. Air Force Reserve Hurricane Hunter reconnaissance aircraft found sustained winds of 40 m.p.h. (65 km/h). As a result, the National Hurricane Center classified the system as Tropical Storm Colin. At 11:00 p.m. EDT on Sunday the center of Tropical Storm Colin was located at latitude 23.6°N and longitude 87.8°W which put it about 450 miles (720 km) southwest of Tampa, Florida. Colin was moving toward the north at 9 m.p.h. (15 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 1003 mb.
A Tropical Storm Warning has been issued for the portion of the coast from Indian Pass to Englewood, Florida. A Tropical Storm Warning has also been issued for the East Coast from Sebastian Inlet, Florida to Altamaha Sound, Georgia. A Tropical Storm Watch has been issued for the portion of the coast from Altamaha Sound, Georgia to South Santee River, South Carolina.
The circulation of Tropical Storm Colin is very asymmetrical. The stronger winds and most of the thunderstorms are east of the center of circulation. Some rotation in the middle levels in the primary band on the east side of Colin is apparent on satellite imagery. Winds to tropical storm force are occurring up to 185 miles (295 km) from the center of circulation. However, the winds are much weaker in the western half of the circulation.
The environment around Tropical Storm Colin is marginal for intensification. Colin is moving over water where the Sea Surface Temperature is near 28°C to 29°C. So, there is sufficient energy in the upper ocean to support intensification. An upper level low near Texas and an upper level ridge east of Colin are combining to produce southwesterly winds that are blowing over the western half of the storm. Those winds are causing strong vertical wind shear which is preventing the development of thunderstorms in that part of the storm. Part of the upper level ridge is over the eastern half of the circulation. The upper level winds are weaker there and there is less vertical wind shear, which is allowing strong thunderstorms to persist in that part of Colin. The upper level ridge is also enhancing upper level divergence to the east of Tropical Storm Colin. If a new center of circulation were to form closer to the upper level ridge, then more intensification would be possible. Colin is likely to intensify somewhat on Monday.
The upper low and upper level ridge are also steering Tropical Storm Colin toward the north. Those features are expected to turn Colin toward the northeast on Monday. On its anticipated track Tropical Storm Colin will approach the coast of Florida between Tampa and Apalachicola on Monday evening. However, if a new center of circulation develops farther east, Colin could make landfall farther south along the coast and earlier on Monday.
Heavy rainfall is the greatest risk with Tropical Storm Colin. It is pulling very humid air from the Caribbean Sea northward over the eastern Gulf of Mexico. Tropical Storm Colin could also generate a storm surge of 1-6 feet near where the center makes landfall. The coast along the northeastern Gulf of Mexico is very susceptible to storm surges and water rises will occur in that area. Wind damage is likely to be minimal, although power outages may occur. Some tornadoes could be generated when Colin moves over land. Locally heavy rain could also fall in portions of the Mid-Atlantic states as the circulation of Tropical Storm Colin interacts with a cold front.
Tropical Storm Colin was named on June 5, which is the earliest date on record on which the third Atlantic Tropical Storm has formed. During the record setting year of 2005 Tropical Storm (later to become Hurricane) Cindy was named on July 5.