Natural-gas prices turn lower after supply data                                 (                                     NGV13                                 )                                by Myra P. Saefong

SAN FRANCISCO (MarketWatch) -- Natural-gas futures turned lower on Thursday after the U.S. Energy Information Administration reported a supply increase of 58 billion cubic feet for the week ended Aug. 30. Analysts polled by Platts forecasted a climb of between 53 billion cubic feet and 57 billion cubic feet. Total stocks now stand at 3.188 trillion cubic feet, down 210 billion cubic feet from the year-ago level and 43 billion cubic feet above the five-year average, the government said. October natural gas     (ngv13)   traded at $3.63 per million British thermal units, down 6 cents, or 1.5%. It was trading slightly higher at $3.69 before the data.