* NHC sees it being major hurricane by Sunday in Atlantic
* Northeast of Leeward Islands by then, but after that?
* Second system watched for possible Gulf of Mexico threat
(Updates with U.S. oil companies monitoring second system)
By Pascal Fletcher
MIAMI, Aug 30 The U.S. East Coast is mopping up
after Hurricane Irene's weekend battering that killed around 40
people and authorities and residents are looking out anxiously
over the Atlantic and asking: Is another one coming?
Tropical Storm Katia is jogging west at a brisk 18 miles
per hour (30 km per hour) and the U.S. National Hurricane
Center says it is expected to become a hurricane by late
Wednesday or early Thursday.
But beyond predicting Katia will be a major hurricane
northeast of the Caribbean's northern Leeward Islands by
Sunday, the Miami-based center says it is not possible now to
predict its path with certainty, or say whether it will
threaten the U.S. East Coast.
"It's still well out to sea. A lot of things can happen ...
We don't show it affecting any land areas for five days. Beyond
that is merely speculation," NHC senior hurricane specialist
Richard Pasch told Reuters.
Nevertheless, he recommended that the U.S. East Coast and
the Caribbean should "keep an eye" on Katia.
At 11 a.m. EDT (1500 GMT), Katia was about 630 miles (1,010
km) west southwest of the southernmost Cape Verde Islands,
still far out to the east in the Atlantic.
Some private forecasters were citing long-range models
beyond five days, some of which show Katia swinging over
Bermuda toward Canada and avoiding the U.S. coast. But Pasch
cautioned such long-range predictions were unreliable and
contained errors of "hundreds of miles" in the envisaged
"You can look at what the long range forecasts did with
Irene, taking it across Miami, which of course didn't happen,"
he said, stressing that even the NHC's five-day forecast "cone"
had an average margin of error of about 250 miles (400 km).
Pasch said Katia's likely track in about a week's time will
depend on shifting weather patterns over the Atlantic and the
U.S. coast -- troughs and ridges that will steer the gyrating
storm in one direction or another.
EYES ALSO ON SECOND WEATHER SYSTEM
"The long term fate of Katia is unknown," hurricane expert
Jeff Masters of private forecaster Weather Underground wrote in
He cited a historical probability chart drawn up by Robert
Hart of Florida State University indicating that tropical
storms in Katia's current position had a 19 percent chance of
hitting North Carolina, a 16 percent chance of hitting Canada,
an 11 percent chance of hitting Florida, and a 47 percent
chance of never hitting land.
Meanwhile, U.S. oil companies were monitoring another
weather system in the northwest Caribbean Sea that some
forecasters say may develop this week into a tropical storm in
the northwest Gulf of Mexico, home to the U.S. offshore oil
The hurricane center gave the system, which was expected to
move west across the Yucatan peninsula, a 10 percent chance of
becoming a tropical cyclone in the next 48 hours, but added it
could develop further when it reaches the western Gulf.
U.S.-regulated Gulf of Mexico areas account for roughly 30
percent of U.S. oil production and 12 percent of natural gas
output, the U.S. Bureau of Ocean Energy Management says.
Irene was the first hurricane to form in the busy 2011
Atlantic storm season. It was a Category 1 hurricane on the
five-step Saffir-Simpson scale when it swept from North
Carolina to New York on Saturday and Sunday. It was the first
hurricane to hit the U.S. mainland since Ike pounded Texas in
But although it subsequently slackened to a tropical storm,
its large width, at times more than 500 miles (800 km) across,
swirled rains and winds over a huge area, causing the worst
flooding in decades in New Jersey and Vermont.
The NHC sees Katia becoming a major Category 3 hurricane by
Sunday morning on its track over warm ocean waters, which act
as boosters for a hurricane's power.
"Bear in mind, it's the end of August, the beginning of
September, it's the peak of the hurricane season," Pasch said.
He said Katia was in the main development region -- the
broad Atlantic bowling alley down which rotating storms roll
off the coast of West Africa.
Forecasters have predicted a very active 2011 Atlantic
season with between eight and 10 hurricanes, above the
long-term June to November average of six to seven hurricanes.
(Additional reporting by Erwin Seba and Kristen Hays in
Houston; editing by Mohammad Zargham)