Natural-gas prices closed barely higher Monday, advancing a new three-week high as weather forecasts show summer heat on the way. The front-month September contract settled up 0.3 cent, or 0.1%, at $3.965 a million British thermal units on the New York Mercantile Exchange. It was the highest closing price since July 16 and the market crested at $4 overnight for the first time since then. It was the fifth gain in the last six sessions. Traders showed a mixed opinion on what was ultimately a mixed weather forecast, analysts said. While forecasts do show some of the strongest heat of the summer, they also show unseasonably cool weather in the immediate few days and a cold front from Canada pushing back into view late next week. That left the market wary over whether the […]