"I think he's just going to test the waters a little bit and see how it goes," Bowman said by phone from Baltimore. "I wouldn't say it's a full-fledged comeback."
Phelps returned to training last fall and re-entered the U.S. drug-testing program. He has completed his six-month waiting period by the U.S. Anti-Doping Agency to be eligible for competition.
Bowman said Phelps is "pretty far" from being back in top form. He's been training Monday through Friday with Bowman's team at the North Baltimore Aquatic Club.
"He's gotten back into good shape since September," the coach said. "He can give a good effort and certainly not be embarrassed. He's in enough shape to swim competitively."
Besides Phelps, USA Swimming said Olympians Ryan Lochte and Katie Ledecky are among those expected to swim in the Arena Grand Prix at Skyline Aquatic Center.
Phelps turns 29 in June and is the winningest and most decorated athlete in Olympic history. He captured 18 gold medals and 22 medals overall at the last three Summer Games. He broke Mark Spitz's record for a single Olympics by winning eight gold medals at Beijing in 2008.
Phelps had vowed that he wouldn't swim into his 30s. His camp is being low key about the comeback.
"I think he's just really enjoying it," Bowman said.