MIAMI, (Reuters) – Powerful Hurricane Earl churned  toward the eastern U.S. seaboard yesterday and looked to  sideswipe the densely populated coast from North Carolina to  New England, the U.S. National Hurricane Center said.

Forecasters expected the main core of the Category 4  hurricane to stay offshore as Earl moved parallel to the coast  during the upcoming Labor Day holiday weekend that  traditionally marks the end of summer.

A hurricane watch was issued for most of the North Carolina  coastline as officials warned any westward deviation from the  forecast track could prompt coastal evacuations or even bring  the storm ashore.

“A small error of 100 miles (160 km) in the wrong direction  could be a huge impact difference,” National Hurricane Center  Director Bill Read told a conference call with journalists.

“Even a minor shift back to the west could bring impacts to  portions of the coastline from the mid-Atlantic northwards.”

The hurricane watch, issued by the Miami-based hurricane  center, alerts residents that hurricane conditions — sustained  winds of 74 mph (119 kph) — are possible within 48 hours. It  covered the North Carolina coastline up from Surf City to the  state’s border with Virginia, including the Pamlico and  Albemarle Sounds.    Earl, the second major hurricane of the 2010 Atlantic  season, was moving west-northwest in the open Atlantic on  Tuesday, keeping well east of the Turks and Caicos Islands.

At 8 p.m. (0000 GMT), it was centered about 835 miles  (1,545 km) south-southeast of Cape Hatteras, North Carolina.

Earl was forecast to clip the barrier islands of North  Carolina’s Outer Banks tomorrow night and bring drenching  rain, rough seas, pounding surf and gusting wind to the  Atlantic Coast from North Carolina to New England and Atlantic  Canada.

Evacuations were ordered, or expected, for yesterday for  the most vulnerable spots on the Outer Banks, including the  Cape Lookout National Seashore and Ocracoke Island, which has  about 800 year-round residents and is accessible only by boat.  It is one of the barrier islands where the pirate Blackbeard  once roamed.

Earl had top sustained winds of 135 miles per hour (215  kph), making it a Category 4 storm on the five-step  Saffir-Simpson intensity scale. It was expected to stay just  shy of a maximum Category 5.