June natural-gas contract jumped to $6.198 per million British thermal units, up 14.2 cents after touching a high at $6.33.
Greenspan helps rally natural gas

Natural-gas prices rallied after Federal Reserve Chairman Alan Greenspan reignited concerns about the tightness of natural-gas inventory in the U.S. during congressional testimony Wednesday.

"It's an extremely serious problem," he said, pointing out that gas supplies in storage are at "extremely low levels, and the normal seasonal rebuilding of these inventories seems to be behind the typical schedule."

Earlier this week, the National Oceanic and Atmospheric Administration predicted an active hurricane season for the Gulf Coast and East Coast, feeding concerns that the severe weather will disrupt natural-gas output from that region.

"This market could explode with increased dangers from hurricanes in the Gulf of Mexico and of course a massive summer heat wave drawing demand from power plants who use natural gas," said Person.