NEW YORK — Fox will bring only two new series on the air in the fall, traditionally its slow season, but plans flashy two-hour season premieres of four programs during the same August week as the Democratic National Convention.

Lost producer J.J. Abrams is behind the new science fiction drama, Fringe, about an airplane flight whose passengers meet untimely ends. Fringe will be paired on the schedule with House on Tuesdays in the fall and American Idol in the spring.

A new comedy, Do Not Disturb, is set in one of Manhattan’s trendiest hotels. It replaces the canceled Back to You (the wife of disappointed star Kelsey Grammer is encouraging an Internet petition to get it back).

Fox will finish the season as the nation’s most popular network among all viewers, instead of just young viewers, taking a title owned by CBS for the past five years.

Fringe, Bones, Prison Break and Are You Smarter Than a 5th Grader? will open the fall season the week of Aug. 25.

They should not conflict with major moments of the convention because political planners try to time them after 10 p.m. on the East Coast, when the Fox shows will be over, said Peter Liguori, Fox entertainment chairman. Fox is avoiding any conflict on Thursday, when the party’s nominee gives an acceptance speech.

Fox executives said their development season was hindered by the writers strike, one reason why only two new series will premiere in the fall.

But Fox usually comes alive in January, anyway, when American Idol premieres. Fox will introduce another new sci-fi series, Dollhouse, two animated and one alternative series in midseason.

Fox executives said they were disappointed with the ratings declines for American Idol this season, and will cut back the Wednesday results show to 30 minutes.