Howell, of England and Sweden's Edfors shot 5-under-par 67s for a one-shot lead over five players.
The 29-year-old Englishman had been 6-under but bogeyed the final hole.
"Everything went nicely for me early on and no mistakes until on the last there, but that's golf sometimes," Howell said. "Frustrating, but I could have bogeyed the first, it just happened to be the last."
Defending champion Adam Scott was in a group at 72.