Rain bands could result in occasional moderate to heavy showers with periods of rain and thunderstorm activity are likely across the Eastern Caribbean overnight into Thursday and Friday, as the center of ‘Isaac’ passes through the Lesser Antilles. Instability resulting in showers could be enhanced by a south south-easterly wind flow at the lower levels and supported by mid and upper level conditions
well into Saturday to possibly decrease by Saturday night. Models suggest that rainfall accumulations of 50 to 75 mm (2 to 3 inches) are possible across parts of SVG associated with the passage of “Isaac”.
At 5:00 pm, the center of Tropical Storm Isaac was located near latitude 15.4 North, longitude 56.6 West. From the image at 5:15pm (compliments RAMMB)...The circulation is visible and the center is exposed on the western side of a re-developing band of convection on the eastern side.
Gentle northerly breeze should be experienced overnight into Thursday, becoming calm at times. As the system moves across the Lesser Antilles a shift in wind direction to southerly and an increase in wind speeds to moderate breeze (20-30km/h) can be expected by mid morning /afternoon Thursday.
Moderate to fresh (25 - 40km/h) breeze may be felt across parts of SVG from Thursday night continuing into Saturday.
Barometric Pressure should range 1008mb - 1010mb, some fluctuations are expected with the approach and passage of Isaac north of our area on Thursday.
Swells are increasing across SVG, with swells on the west coast possibly reaching up to 2.0m (6.5ft), while on the east coasts swells could reach up to 3.0m (10ft) by Thursday, decreasing late Friday.
Notes:
- A new tropical wave is just offshore the coast of Africa along 18W from 03N to 20N, moving westward at 10 to 15 kt. The wave is supported by well pronounced 700 mb troughing. Scattered moderate convection is seen within 120 nm west and 60 nm east of the wave axis from 15N to 19N.
- At 5:00 PM, the center of newly formed Subtropical Storm Joyce was located near latitude 34.3 North, longitude 41.9 West.
- At 5:00 PM, the center of Hurricane Helene was located near latitude 21.4 North, longitude 36.7 West. Helene is moving toward the north near 14 mph (22 km/h). A turn toward the northeast with an increase in forward speed is expected during the next few days.
- At 5:00 PM, the center of Hurricane Florence was located near latitude 30.9 North, longitude 72.5 West. Florence is moving toward the northwest near 16 mph (26 km/h), and this general motion, accompanied by a gradual decrease in forward speed, is expected to continue through Saturday. On the forecast track, the center of Florence will move over the southwestern Atlantic Ocean between Bermuda and the Bahamas tonight, and approach the coast of North Carolina or South Carolina in the hurricane warning area on Thursday and Friday, and move slowly near the coastline through Saturday. Maximum sustained winds have decreased to near 120 mph (195 km/h) with higher gusts. Florence is a category 3 hurricane on the Saffir-Simpson Hurricane Wind Scale. Some fluctuations in strength will be possible through Thursday morning. Although slow weakening is expected to begin by late Thursday, Florence is forecast to be an extremely dangerous major hurricane when it nears the U.S. coast late Thursday and Friday.