The National Hurricane Center continues to track one system in the Atlantic and another in the Caribbean that could develop into the next tropical or subtropical depression of the season as they mix with surrounding weather systems.
The chances of a Caribbean formation come from what is expected to be a combination of an existing deep layer trough that has been stationary from eastern Hispaniola to the central Caribbean over the past day with a tropical wave moving west through the Eastern Caribbean.
The trough already features active thunderstorms and, combined with the surge, could increase in intensity affecting Puerto Rico, the US and British Virgin Islands and the Dominican Republic through Friday, forecasters said.
“Excessive heavy rain will likely result in localized flooding in parts of these islands through at least Thursday evening,” said NHC chief forecaster Scott Stripling.
The National Weather Service issued a flash flood warning for parts of western Puerto Rico through Thursday morning. The island is still recovering from the heavy rains that flooded the island during Hurricane Fiona earlier this season.
By Friday, the merging of the two systems will cause it to move westward and weaken while over the weekend an area of low pressure is expected to form over the eastern Caribbean Sea.
“Environmental conditions are expected to be favorable for gradual development, and a tropical depression could form early next week as the disturbance moves generally west or west-northwestward across the Caribbean Sea. central,” Stripling said.
The NHC gives it a 50% chance of forming within the next five days.
To the north of the system in the southwest Atlantic Ocean is a low pressure system stretching from the eastern Caribbean Sea to the north that continues to produce a large area of showers and disorganized thunderstorms .
A surface low pressure system is expected to form to the north which could allow subtropical development.
“A subtropical depression could form over the next two days as the system moves north and then meanders west or southwest of Bermuda,” forecasters said.
The NHC gives it a 40% chance of forming within the next two to five days.
Atlantic hurricane season runs through November 30. The season produced 12 named systems, including Hurricane Ian which hit Florida last month.
The next named storm would be Tropical Storm Lisa.