Tropical Storm Don formed east of the Windward Islands on Monday. An Air Force Reserve Hurricane Hunter reconnaissance aircraft found a small, but well defined center of circulation in a cluster of thunderstorms formerly designated Invest 91L. Based on information from the recon plane, the National Hurricane Center classified the system at Tropical Storm Don. At 5:00 p.m. EDT on Monday the center of Tropical Storm Don was located at latitude 11.2°N and longitude 52.6°W which put it about 595 miles (955 km) east of Trinidad. Don was moving toward the west at 17 m.p.h. (28 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 1009 mb.
A Tropical Storm Warning has been issue for Grenada. Tropical Storm Watches are in effect for Barbados, St. Vincent, the Grenadines and St. Lucia.
The reconnaissance plane found a small, tight center of circulation near the surface. A thin band of showers and thunderstorms wrapped partially around the western side of the center. Other thin bands of showers and thunderstorms were occurring north and west of the center. There were fewer showers and thunderstorms in the eastern half of Tropical Storm Don. The circulation of Tropical Storm Don is small and winds to tropical storm force only extend out about 25 miles (40 km) from the center of circulation. Thunderstorms in the band west of the center of circulation were generating some upper level divergence but it was not well developed.
Tropical Storm Don will move through an environment that will be somewhat favorable for intensification during the next several days. Don will move over water where the Sea Surface Temperature is near 29°C. An upper level ridge east of Don is generating easterly winds which are blowing over the top of the tropical storm. Those easterly winds are generating some vertical wind shear and the shear may partly explain why there are fewer showers and thunderstorms in the eastern half of the circulation. The shear will also inhibit intensification, but Tropical Storm Don could strengthen during the next 24 to 48 hours.
A strong subtropical high over the Atlantic Ocean is steering Tropical Storm Don toward the west and a generally westward motion is expected to continue during the next several days. On its anticipated track the center of Tropical Storm Don could pass south of Barbados on Tuesday. Tropical Storm Don could move over the southern Windward Islands on Tuesday night. Tropical Storm Don could bring gusty winds and locally heavy rain to the southern Windward Islands. Flash floods could occur in areas of steep terrain, if they receive locally heavy rainfall.
The National Hurricane Center (NHC) changed the designation of Invest 92L to Potential Tropical Cyclone 02 on Sunday evening. NHC implemented a new policy for 2017 which allows it to issue tropical cyclone watches and warnings before it officially classifies a system as a tropical cyclone. NHC issued Tropical Storm Warnings for some of the Windward Islands because of Potential Tropical Cyclone 02 on Sunday evening in accordance with the new policy.
At 11:00 p.m. EDT on Sunday the center of Potential Tropical Cyclone 02 was located at latitude 7.9°N and longitude 52.4°W which put it about 630 miles (1015 km) east-southeast of Trinidad. It was moving toward the west-northwest at 23 m.p.h. (37 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 1005 mb.
Tropical Cyclone Warnings have been issued for Barbados, St. Vincent, the Grenadines, Grenada, Trinidad, and Tobago.
The circulation of Potential Tropical Cyclone 02 appeared to get better organized on Sunday evening. Satellite imagery seemed to indicate that a more circular area of thunderstorms was forming around the center of circulation. The system was already producing sustained winds to 40 m.p.h. (60 km/h) and if a center of circulation develops, it will be classified as a tropical storm.
Potential Tropical Cyclone 02 will move through an environment that will be somewhat favorable for intensification during the next 24 hours. It will move over water where the Sea Surface Temperature is near 29°C. An upper level trough over the eastern Caribbean Sea is generating southwesterly winds that are causing some vertical wind shear. Potential Tropical Cyclone 02 has about 24 to 36 hours before the shear increases significantly. After that time the system will weaken.
A subtropical high pressure system over the Atlantic is steering Potential Tropical Cyclone 02 toward the west-northwest. A general west-northwesterly motion is expected to continue. On its anticipated track Potential Tropical Cyclone 02 will reach the southern Windward Islands later on Monday. It will bring gusty winds and locally heavy rain when it gets there.
A tropical disturbance designated as Invest 97L poses a potential risk for locations around the Caribbean Sea. At 8:00 p.m. EDT on Tuesday the center of Invest 97L was located at latitude 13.1°N and longitude 55.3°W which put it about 285 miles (460 km) east of Barbados. Invest 97L was moving toward the west at 19 m.p.h. (31 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. (70 km/h). The minimum surface pressure was 1008 mb.
A U.S. Air Force Reserve Hurricane Hunter aircraft flew a reconnaissance mission into Invest 97L on Tuesday afternoon. The plane found the there were winds to near tropical storm force, but it could not identify a closed circulation. The winds on the western side were weaker and the plane was unable to find a surface center. There does seem to be cyclonic rotation above the surface at least on infrared satellite imagery.
The circulation in Invest 97L is still organizing. Many of the stronger thunderstorms are forming north and east of the apparent center on satellite imagery. Rainbands are also forming north and east of the center. Recent satellite images suggest that some thunderstorms could be developing closer to the center of cyclonic rotation. The current thunderstorms are generating upper level divergence which is pumping out mass to the north and east of the system.
Invest 97L is moving through an environment that is favorable for intensification. It is moving over water where the Sea Surface Temperature is near 29°C. The upper level winds over the majority of the circulation are relatively weak. An upper level trough over the Caribbean Sea is generating vertical wind shear over the northern fringe of the circulation. Invest 97L could become a tropical storm at any time.
A subtropical high pressure system to the north of Invest 97L is steering it toward the west and that general motion is expected to continue for another day or two. On its anticipated track Invest 97L will move through the Windward Islands near Barbados, St. Lucia, Martinique, and Dominica on Wednesday. It could bring gusty winds and locally heavy rain to those locations.