* NOAA cuts Atlantic hurricane forecast
* Agency predicts 7-11 tropical storms, 3-6 hurricanes
* El Nino is strengthening, which calms storm development
* 2009 will be near-normal or below-normal, NOAA says
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By Jane Sutton
MIAMI, Aug 6 (Reuters) - The U.S. government climate agency cut its 2009 Atlantic hurricane season forecast on Thursday, predicting between seven and 11 tropical storms, with three to six becoming hurricanes.
The National Oceanic and Atmospheric Administration predicted one to two of those would be "major" hurricanes of Category 3 or higher, with sustained winds of more than 110 miles per hour (177 km per hour).
The agency had predicted in May that there would be nine to 14 tropical storms, with four to seven becoming hurricanes, and one to three strengthening into major hurricanes.
Hurricanes can disrupt U.S. energy production in the Gulf of Mexico and ravage crops in the southeastern United States and Caribbean, sending prices soaring for fuel, orange juice, sugar, coffee and cotton.
Seasonal forecasts are sometimes good at predicting broad, general trends. But NOAA said such long-range forecasts cannot predict whether or when a specific location might be endangered, or the potential financial impact, because those things depend on conditions that change often.
The change in the seasonal forecast was based mainly on the arrival of El Nino, a periodic warming of sea waters in the eastern Pacific. El Nino can suppress Atlantic hurricane activity by increasing wind shear, a difference in wind speeds at different altitudes that can tear apart nascent cyclones.
"El Nino is here," said Gerry Bell, the agency's lead seasonal hurricane forecaster.
"El Nino developed very rapidly in June and it very quickly started having very significant impacts on the wind patterns throughout the tropics."
In May, NOAA had calculated there was a 50 percent chance El Nino would develop.
NOAA now expects a normal to below-normal season, Bell said. An average season brings 11 tropical storms, with six strengthening into hurricanes and two becoming major hurricanes.
Bell warned against complacency, adding, "By no means do we expect the season to be dead."
The Atlantic-Caribbean hurricane season, which runs from June 1 to Nov. 30, has not generated any tropical storms so far. But the busiest part of the season is usually from late August to mid-October.
"The calm start to this hurricane season is not a reliable indicator of the overall activity for the entire season," NOAA warned in the forecast.
(Editing by Jim Loney and Eric Beech)