Cape Canavarel, Fla. ? Caught between a worrisome weather forecast and their need to launch the long-delayed space shuttle Atlantis mission, NASA officials will decide this morning whether to proceed with their countdown or to roll the shuttle back into its protective hangar.

NASA officials were pessimistic Sunday night about their chances for a launch this week, but said they wanted to allow Tropical Storm Ernesto a little more time to change course. Current projections bring the storm to Cape Canaveral by midweek, and officials said they could not risk leaving Atlantis on its launch pad if the forecast doesn’t improve.

The launch already has been delayed by two days because of stormy weather and concerns that a Friday lightning strike might have damaged the vehicle. But after several days of testing for damage, NASA concluded Sunday that the shuttle was in good flying condition.

LeRoy Cain, launch integration manager, said that although NASA would make a go/no-go decision this morning, the team had until noon Tuesday to rescind a decision to scrub the flight. He said if the weather forecast then changed substantially, Atlantis could be launched later in its 11-day launch window.