Natural gas briefly surged above $9 per million British thermal units in the US for the first time since 2008, extending a breakneck rally as fears of a supply crunch intensified, before paring gains into close. Stockpiles of the heating and power-plant fuel are below normal for this time of year as exports are booming, and output from shale basins is muted. Traders anticipate higher-than-usual gas needs this summer to fuel US power plants as consumers and businesses crank up air conditioners to combat hotter weather. Meanwhile, hydro-power generation and coal supplies are severely constrained, leaving limited alternatives to gas. Reflecting growing concerns about replenishing depleted stockpiles ahead of the winter, gas for July delivery has traded at an unusual premium over contracts for February. And the so-called widowmaker spread between gas delivered in March and […]