Gulf Coast gasoline strengthened after Alon USA Energy Inc. (ALJ) reported emissions from a catalytic cracker at a Texas refinery and a tropical storm moved toward the U.S. refining center.

Alon’s Big Spring plant had emissions from a boiler and fluid catalytic cracker after the rupture of a boiler tube, according to a filing yesterday with the Texas Commission on Environmental Quality. Tropical Storm Isaac is forecast to strengthen and cross Haiti and Cuba before arriving on the southwestern Florida coast Aug. 27, the National Hurricane Center said.

The premium for conventional, 87-octane gasoline in the Gulf Coast rose 1.25 cents to 9.5 cents a gallon versus October futures traded on the New York Mercantile Exchange at 12:10 p.m., according to data compiled by Bloomberg. Prompt delivery rose 3.55 cents to $3.0562 a gallon.

The premium for ultra-low-sulfur diesel in the Gulf slipped 0.25 cent to 8.5 cents versus heating oil futures, the lowest level since Aug. 16.

To contact the reporter on this story: Paul Burkhardt in New York at pburkhardt@bloomberg.net.

To contact the editor responsible for this story: Dan Stets at dstets@bloomberg.net.