Fireworks burst forth over the Philadelphia Museum of Art before midnight on the nation's 231st birthday, even if many rain-soaked revelers had heeded the city's advice and gone home.
   City officials, worried about looming storms, at one point nixed the fireworks show and urged the crowd to leave the Benjamin Franklin Parkway. But the skies soon cleared, prompting them to reverse course and start the fireworks display at about 11:20 p.m.
   The move to start the show after many had left sparked outrage among those who missed out.