Second round co-leader Summerhays was set to take 19-foot putt on the final hole, seeking to forge a tie with Nicholas Thompson at 17-under-par 199, but had to endure a 1-hour, 15-minute weather delay as three players remained on the course.
The layoff didn't affect his concentration, however, and he returned to make the putt, finishing out a round of 3-under 69 to stay on top of the leaderboard.
Thompson, meanwhile, tied the low round of the day at Annandale Golf Club with a 7-under 65, also ending at minus-17.
Summerhays was one of several golfers who finished their second rounds Saturday morning after Friday's play was suspended due to darkness.
Knotted for seventh at 14-under were Brendon Todd (66), Vaughn Taylor (68) and Bill Lunde (68).