* Igor could become Category 5 storm on Monday
* No immediate threat to land or energy interests
* Tropical Storm Julia moves over eastern Atlantic (Updates storm positions, adds comment)
MIAMI, Sept 13 (Reuters) - Powerful Hurricane Igor churned westward in the Atlantic Ocean as a dangerous Category 4 storm and could strengthen even further on Monday, forecasters said.
Igor was strong enough to cause catastrophic damage but posed no immediate threat to land or energy interests. It was too soon to rule out an impact on the U.S. East Coast, but the chances of such a landfall were viewed as slim.
The major hurricane had top sustained winds of 150 miles (240 km) per hour and could turn to a Category 5 storm on the five-step Saffir-Simpson scale of hurricane intensity, forecasters at the U.S. National Hurricane Center said.
All the computer models keep Igor in the Atlantic and away from the Gulf of Mexico, where U.S. oil and gas operations are clustered.
Behind Igor, Tropical Storm Julia developed over the far eastern Atlantic Ocean on Sunday, becoming the 10th named storm of the 2010 Atlantic hurricane season.
Igor, the fourth hurricane of the 2010 Atlantic season, was centered 880 miles (1,420 km) east of the Caribbean's northern Leeward Islands at 11 a.m. EDT (1500 GMT), the Miami-based center said.
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Igor seemed to be nearing its peak intensity but it wouldn't take much to boost it into the highest level of a Category 5 storm, with winds topping 155 mph (249 kph), the forecasters said.
Igor was moving west and was expected to turn west-northwest by Tuesday. Computer models disagreed on how sharp a turn Igor would take, said Michael Brennan, a senior hurricane specialist at the hurricane center.
A west-northwest track would take it near Bermuda on Saturday but a sharper northerly turn would keep it over the open Atlantic.
"Bermuda's probably at the greatest risk of seeing an impact from Igor but it's too soon to say whether it would approach the (U.S.) East Coast," Brennan said.
So far this year, the atmospheric conditions that steer hurricanes in the western Atlantic have cooperated to push them away from the densely populated U.S. coast.
Gaps have opened in the subtropical ridge, allowing the storms to move north, while a series of troughs rolled eastward off the U.S. coast, making the storms curve away. But there was no guarantee that pattern would last until the six-month hurricane season ends on Nov. 30, forecasters said.
"It's pretty much a matter of timing," Brennan said. "It's something that evolves day to day."
Tropical Storm Julia also posed no immediate threat to land. It was 115 miles (185 km) west of the Cape Verde Islands and was moving west-northwest away from those islands.
Julia had top sustained winds of 40 miles (65 km) per hour and could strengthen into a hurricane in a couple of days, the hurricane center said.
Most forecasters predicted the 2010 Atlantic hurricane season would be extremely active. Besides Igor, three hurricanes -- Alex, Danielle and Earl -- formed earlier in the season, the last two reaching Category 4 strength. (Reporting by Tom Brown and Jane Sutton; Editing by Pascal Fletcher and Philip Barbara)