At 5am Atlantic Time, Tropical Storm Isaac was churning about 500 miles southeast of the Caribbean island Martinique, part of the Lesser Antilles.
Isaac is packing winds of 60 mph, and is moving westward at 15 mph, according to the National Hurricane Centre (NHC).
On the forecast track, Isaac is expected to hit the central Lesser Antilles and move into the Caribbean Sea on Thursday.
A National Oceanic and Atmospheric Administration (NOAA) aircraft is scheduled to investigate the storm further on Wednesday, but at this stage it looks like rainfall, wind, storm surge and surf will pose a serious threat.
Watches and warnings in place:
A Tropical Storm Warning is in effect for:
A Tropical Storm Warning means that tropical storm conditions are expected somewhere within the warning area within 36 hours.
A Tropical Storm Watch is in effect for:
- St. Kitts and Nevis
- Saba and St. Eustatius
A Tropical Storm Watch means that tropical storm conditions are possible within the watch area, in this case within 36 to 48 hours.
The NHC advises those in the Leeward islands should keep a close eye on the storm as the situation progresses.
Isaac is expected to produce total rainfall accumulations of 2 to 4 inches, with isolated amounts up to 8 inches across Martinique, Dominica, and Guadeloupe.
Up to one inch of rain is anticipated across the remaining Windward and Leeward Islands.
Strong winds are expected on Martinique, Dominica, and Guadeloupe by late Wednesday or early Thursday.
Some coastal flooding is possible due to storm surge, and will be accompanied by large waves.
Swells generated by Isaac will begin to affect portions of the Lesser Antilles on Wednesday afternoon.
The NHC warns these swells are likely to cause life-threatening surf and rip current conditions.
The impact of Isaac depends on the wind shear it encounters as it heads across the water.
Wind shear, or the change in wind direction and/or speed with altitude, can rip apart any tropical system, but especially smaller systems such as Isaac.
Regardless of strength, indirect impacts in the form of rough surf and increased rip currents will arrive on the east-facing beaches of the Windward and Leeward islands by Wednesday.
Latest indications point toward the storm tracking between the islands of St. Lucia and Antigua.
Many of these islands are still rebuilding following Hurricane Maria, which crossed the Lesser Antilles and moved over Puerto Rico almost a year ago.