NEW YORK (REUTERS) - Isaias has weakened into a tropical storm over eastern North Carolina, the US National Hurricane Centre said on Tuesday (Aug 4).

Isaias, packing maximum sustained winds of 110kmh, is located about 55km west south-west of Greenville, North Carolina, the Miami-based forecaster said.

Although Isaias is now a tropical storm, it could still bring"strong winds, heavy rainfall, and the threat of tornadoes beginning to spread into southeastern Virginia", the NHC added.

Isaias made landfall in Southern North Carolina on Monday night as an Atlantic hurricane, the United States National Hurricane Centre said.

When it made landfall, Isaias was packing maximum sustained winds of 140km per hour.

It is churning its way up the United States East Coast towards Washington, Philadelphia and New York, the Centre said.

Isaias posed an immediate threat to a stretch of coastline that includes the South Carolina tourist resort of Myrtle Beach and the North Carolina port city of Wilmington.

In a warning to the Carolinas, the National Hurricane Centre said: "Preparations to protect life and property should be rushed to completion."

New York City braced for a potential storm surge in lower Manhattan, mindful of devastation caused by Superstorm Sandy in 2012.

While a few local officials on the East Coast ordered evacuations, North Carolina Governor Roy Cooper warned of severe inland flooding, as occurred with 2018's Hurricane Florence, which killed 40 people and caused US$17 billion (S$23.37 billion) in damage in the state.

A storm surge warning was posted for a 289km stretch of the coastline from Folly Beach, South Carolina, north to Cape Fear, North Carolina.

Swift-water rescue teams, high-water vehicles and helicopters were standing by in North Carolina, and storm shelters were preparing to accommodate evacuees with at least 10sq m per person to assure Covic-19 social distancing.

Coronavirus diagnostic testing sites were being left to decide on a case-by-case basis whether to close, stay open or alter their testing hours, according to the state's health department.

"North Carolinians have had to dig deep in recent months to tap into our strength and resilience during the pandemic...but we have to dig a little deeper. Let's keep each other safe from the wind and water, as well as from the virus," Governor Cooper said.

Hatteras Island, a barrier island popular with tourists, was nearly deserted on Monday after officials ordered visitors and residents to leave, but some ignored the warnings.

Mr Kevin Rowe, 63, of Indiana, was not about to let the storm cancel his family's first visit to North Carolina's Outer Banks.

"We're a little bit of risk-takers," said Mr Rowe, who has been travelling the world for 11 years with his wife.

Isaias is the ninth named storm of the 2010 Atlantic hurricane season.