SAN JUAN, Puerto Rico (AP) — Tropical Storm Philippe is threatening to unleash heavy rains and flash flooding in the northeastern Caribbean on Monday before eventually spinning north into the open Atlantic, where it could strengthen into a hurricane around midweek, forecasters say.

The storm was about 95 miles (155 kilometres) east-southeast of Barbuda on Monday morning. Top sustained winds were at 50 mph (85 kph) with higher gusts, and Philippe was moving west-northwest at 7 mph (11 kph).

A tropical storm watch was in effect for Antigua and Barbuda. Forecasters said people in the northern Leeward Islands should monitor the storm’s progress as the centre of Philippe was forecast to pass near or just northeast of the archipelago on Monday.

Philippe was forecast to turn north-northwest by late Tuesday and then north on Wednesday.

Rainfall amounts expected through Tuesday include two to six inches (10 to 15 centimetres) for Antigua and Barbuda and two to four inches (5 to 10 centimetres) for the rest of the Leeward Islands, the hurricane center reported.

Heavy rainfall from Philippe also could produce isolated to scattered flash flooding across Antigua and Barbuda through Tuesday, according to the advisory.

Officials in the French Caribbean island of Guadeloupe warned of copious rains starting Monday afternoon, with accumulation of up to 4 inches (10 millimetres) in some areas.

Forecasters said strong wind shear is expected to prevent Philippe from strengthening in coming days, but shifting conditions could allow it to become a hurricane later in the week.