For the second day in a row, NASA has put off the launch of the shuttle Discovery due to stormy weather. Launch officials say there was "no hope" that showers and thunderstorms would end in time for today's 3:26 p-m, Eastern time, launch. The next attempt will be on Tuesday, July Fourth, at 2:38 p-m Eastern time. The 48-hour delay gives the work force a day of rest and achance to replenish the shuttle's on-board fuel. The weather is expected to improve by Tuesday, although rain is still in the forecast.