Tropical Storm Henri will complete almost a full circuit around Bermuda before heading out into the Atlantic and forming into a hurricane, according to forecasters.

The unusual “loop” movement of the storm has been caused by two high pressure systems.

Henri developed as a tropical storm to the northeast of Bermuda on Monday. It headed southwest, skirting the southern shore of the island, before turning west.

It is expected to turn north and track along the US eastern seaboard before turning east into the open Atlantic by the weekend and becoming a hurricane.

According to an update from the US National Hurricane Centre at 8am today, Henri was 295 nautical miles to the southwest of Bermuda, but continuing to move away to the west-southwest.

Although swells could still affect Bermuda in the next 48 hours, there are no coastal warnings or watches in effect.

Explaining the unusual movement of Henri, Mark Guishard, director of the Bermuda Weather Service, said: “High pressure is currently strengthening north and east of Bermuda. As the high builds, it’s been pushing Henri south of Bermuda, resulting in this looping track around the island.

“Later in the week, the high to the north of Bermuda will weaken, which will allow Henri to start its turn to the northwest Thursday or Friday.

“Nonetheless, the Bermuda Azores high is predicted to continue to keep Henri away to the west of Bermuda as it re-curves into the mid-latitudes.”