The slow-rolling storm system named Henri is taking its time drenching the US north east with rain, with a slated turn to the east from upstate New York back through New England.

The National Weather Service in Boston said torrential downpours and renewed flooding were possible, and there was a chance for brief tornados. The storm, now a tropical depression, was expected to dump another 1in to 3in of rain as its centre moves through Massachusetts.

Flood warnings were in effect for parts of northern New Jersey and south-eastern New York state, and flood watches stretched throughout south-eastern Pennsylvania, parts of Vermont and New Hampshire and New York City.

More than 140,000 homes lost power, and deluges of rain closed bridges, swamped roads and left some people stranded in their vehicles.

Beach towns from the Hamptons on Long Island to Cape Cod in Massachusetts were spared the worst of the potential damage on Sunday, while other areas of New England awaited the storm’s return.

The National Hurricane Centre said Henri is expected to slow down further and stall near the Connecticut-New York border, before moving back east through New England and eventually pushing out to the Atlantic Ocean.

By Monday morning, the system was moving east at just 1mph.

Henri produced 3in to 6in of rain over many areas on Sunday, with isolated higher totals. An additional 1in to 3in was forecast through Monday for parts of Long Island, New England, south-east New York, New Jersey and eastern Pennsylvania.

New England officials were concerned that just a few more inches could cause disaster after a summer of record rainfall.

“The ground is so saturated that it can flood with just another inch of rain,” Connecticut governor Ned Lamont warned late on Sunday.

President Joe Biden has declared disasters in Massachusetts, Rhode Island and Connecticut, opening the purse strings for federal recovery aid to those states.

“We’re doing everything we can now to help those states prepare, respond and recover,” said the president, who also offered condolences to Tennessee residents after severe flooding from an unrelated storm killed at least 22 people and left dozens missing.

When Henri made landfall near Westerly, Rhode Island, it had sustained winds of about 60mph and gusts of up to 70mph.

Some communities in central New Jersey were inundated with as much as 8in of rain by midday on Sunday.

In Jamesburg, video footage showed flooded streets and cars almost completely submerged. In Newark, public safety director Brian O’Hara said police and firefighters rescued 86 people in 11 incidents related to the storm.

In Connecticut, about 250 residents from four nursing homes on the shoreline had to be moved to other facilities. Several major bridges in Rhode Island were briefly closed on Sunday, and some coastal roads were nearly impassable.