Robin Roberts last day Thursday on 'Good Morning America'

Robin Roberts will sign off from “Good Morning America” this morning, Thursday, a day before from her planned departure, she announced Thursday morning. Reason: To be with her mother, Lucimarian, who is ailing and living in Mississippi, Roberts said.

"Our beloved mother, the matriarch of our family, 88-years-old, has had some health issues recently and it's got to the point that Sally-Ann and I need to get home so I'm leaving a day early."  

Roberts will shortly begin preparations for a bone-marrow transplant next week and a recovery process that could take her away from the resurgent show -- resurging largely because of her efforts -- for months. She deflected questions on how long that recovery process would be, only saying (jocularly) to her colleagues, “I know we're going to see moments like this again and have them when I come back..."

Roberts' doctor, Gail Roboz, also on the air Thursday morning, told Roberts -- who will undergo her transplant at Memorial Sloan-Kettering Cancer Center -- that “you look at the first 30 days as time to rebuild your system.” With the transplanted marrow, collected earlier this week from Roberts' sister Sally-Ann, “we wiped out your marrow and immune system, but Sally's .?.?. has to find a way to set up shop in you.” Again, no indication about how long the recovery process will take.

And this: The show announced that the cast of “Modern Family” will stand in for Roberts at some point during her recovery. How can a cast anchor a show? Guess we'll have to watch and see. Other stand-ins include Kelly Ripa, Rob Lowe and “surprise guests.”