The combined power of George Clooney and the Disney brand will propel “Tomorrowland” to first place at the Memorial Day Weekend box office, but Hollywood won’t have as much to celebrate this holiday as it has in years past.

“Tomorrowland” is on track to debut to $40 million for the three-day weekend and just shy of $50 million for the four-day period. That’s a shadow of last year’s Memorial Weekend champ, “X-Men: Days of Future Past,” and its $122.9 million haul, to say nothing of “Pirates of the Caribbean: At World’s End” and its $139.8 million high-water mark. In fact, it’s shaping up to be one of the weakest Memorial Day weekends in recent history.

“Tomorrowland,” a futuristic adventure about… well, that’s not immediately clear from the advertisements, may be the summer movie season’s biggest gamble. Unlike most of the major tentpole films, it’s an original proposition, not a sequel or an adaptation of a beloved comicbook. With a production budget of $180 million, “Tomorrowland” will need strong word of mouth and fantastic overseas business if it is to make a profit. Reviews for the film, directed by “Mission: Impossible — Ghost Protocol” director Brad Bird, have been mixed, which could spell trouble.

“The negative reviews for ‘Tomorrowland’ certainly worry me,” said Phil Contrino, VP and chief analyst at BoxOffice.com. “It’s a sign the film might not hold up as well throughout the course of the weekend.”

Overseas, the film’s dazzling special effects should goose revenues. This weekend, “Tomorrowland” opens in 65 foreign markets.

With “Tomorrowland” something of a question mark at the domestic box office, holdovers “Mad Max: Fury Road” and “Pitch Perfect 2” and fellow newcomer “Poltergeist” may have to pick up the slack. Of these, “Pitch Perfect 2” should be the strongest performer, having dominated last weekend’s box office with a stunning $69.2 million debut. It should taper off in its second weekend, but will still do roughly $40 million for the four-day period.

“Mad Max: Fury Road” has enjoyed some of the best reviews of the year, with critics liberally tossing around the superlatives, but the $150 million production still has a long way to go before it climbs into the black. Look for the apocalyptic adventure to do approximately $30 million for the four-day spell.

“Poltergeist,” a remake of the 1982 haunted house classic, was co-financed by MGM and Fox 2000 for $35 million. Reviews have been negative, but horror films tend to be critic-proof. “Poltergeist” should do $25 million for the four-day frame, but the studio is being more conservative and predicting a debut of $20 million to $22 million for the period.

“There’s a wide array of content programmed for this weekend,” said Paul Dergarabedian, senior media analyst at Rentrak. “There literally is something for everyone, which could pay off.”

The summer box office is up a whopping 14.2% over last summer and 0.58% ahead of the record summer of 2013, but it should surrender some of those gains by the time Tuesday rolls around. Last summer, the Memorial Day Weekend box office hit $232.1 million for the four-day weekend — a huge number, but one that ranks as only the fifth biggest in history. The record was set in 2013, when “Fast & Furious 6” and “The Hangover Part III” combined to boost revenues to $314.2 million over the four days; this year’s holiday weekend will likely pale in comparison no matter how strong a mix of films Hollywood is offering up.

Not all Memorial Days are created equal.