"The Velocity of Autumn," the dark comedy by Cleveland Heights playwright Eric Coble — which enjoyed sell-out crowds and critical success at the Beck Center for the Arts in March — is bound for Broadway with a dream cast.

Academy Award winner Estelle Parsons — last seen in "August: Osage County" at PlayhouseSquare in 2010 — is on board to play Alexandra, an 80-year-old artist who blockades herself in her Brooklyn, N.Y., brownstone and threatens to blow it all to smithereens rather than end her days in a nursing home. (Celebrated Cleveland actress Dorothy Silver wowed local audiences in the lead role at the Beck in 2012.)

Two-time Tony winner Stephen Spinella will play Chris, Alexandra’s estranged son who shimmies into her fortified camp through a window to talk her out of her desperate plan before police break down the door. That’s when the emotional bombs start detonating and don’t stop.

“It’s unreal,” said Coble about his Broadway debut. Though the announcement kept him on the phone all day Thursday — fielding calls from well-wishers and the press — he’s still in the “I’ll believe it when I see it” mode.

“Velocity,” which will be directed by Molly Smith, artistic director of Arena Stage in Washington, D.C., is slated to open in spring 2013, though no firm date has been set.

Producers are raising money to mount the show and are beginning to talk to theaters to secure a home.

“When both those things fall into place, then it’s good to go,” Coble said.

“The Velocity of Autumn” is the last of the Alexandra plays, a trilogy by Coble chronicling the life of a whip-smart, free-spirited artist.

Alex in her 20s is the focus of “A Girl’s Guide to Coffee,” produced by Actors’ Summit in Akron earlier this year. The world premiere of “Graphic Depictions,” which explores her in middle age, will be at the Boise Contemporary Theater in Idaho in April 2013. (“Velocity” also premiered in Boise, in April 2011.)

In the meantime, Coble is gearing up for rehearsals of “A Carol for Cleveland,” a new script based on the novella by Les Roberts, which begins previews at the Cleveland Play House’s Allen Theatre in November.

Now that one of his plays is headed to the Great White Way, will success go to Coble’s head?

With tongue firmly in cheek, he quipped, “I’m expecting little kids to come to our house and give me candy on Halloween now — it’s gonna be a big change.”