JACK KENT COOKE'S musings about taking the Redskins out of Washington and the Orioles and Colts out of Baltimore to occupy a domed stadium in Laurel are misplaced. It is true that RFK Stadium in the District, where Mr. Cooke's Redskins play football, is a comparatively small stadium with only 55,000 capacity. And it can't be said that it has every modern convenience; notably absent are a dome to keep out the rain and the popular box seats that a team can sell for a good price. But it is also true that the stadium is conveniently located in the center of the metropolitan area, not nearly an hour from the city in Laurel, and that it is fed by a wonderful network of roads from every direction as well as a subway. There is parking for 12,500 cars. And it is also true that leaving RFK empty of professional sports would hurt the city, both emotionally and financially, and create as well some awful thing called the Laurel Redskins.

Mr. Cooke may not be moved by the city's attachment to the Redskins if his primary concerns are financial ones. But doing well financially and keeping the Redskins in RFK are not mutually exclusive. The stadium could be expanded. The exact same stadium design fits 7,500 more people in Atlanta. That many seats were removed from the stadium here to allow it to have a wavy roof, thus satisfying the Fine Arts Commission's objections to a straight- line roof in the city's skyline. There are also plans to construct 75 boxes in the stadium, with a potential seating capacity of another 1,000 seats. Building a dome on RFK is also possible. What is needed to make these things happen is that money be invested. However much it costs, it would probably be cheaper to redo RFK than to build a new stadium.

There is the chance in this that Mr. Cooke is bluffing and using talk of a Laurel stadium to prompt RFK Stadium's operators to lower the rent. Let's hope so. Putting the Redskins in Laurel would not only deprive Washington of pro football. It would also kill all chances of getting pro baseball back here. Who could argue for bringing a baseball team here after the Orioles move even closer?

That brings up another argument against the idea of a new stadium: the reaction in Baltimore to moving the Orioles. This newspaper--after having been rash enough to suggest relocating the Orioles in Washington--has been persuaded that the Orioles belong in Baltimore. They are a part of that city, and bringing them here would be shortsighted because it would alienate most of Maryland and ruin team support. Moving the Orioles and the Colts to Laurel would have the same negative effect on the fans, and without fans the new stadium would be a bust, a money-loser.

In Baltimore they are now working on plans for a new stadium. Along those same lines, renovations of RFK here are in line if Mr. Cooke genuinely feels that the stadium is out of date and that it is costing him money. The Redskins belong in Washington.