Singh, who shared the lead after the second round, only managed a 1-over 72 on Saturday, but joined Scott, the first-round leader, at minus-7. Scott carded a 2-under 69 in round three.
Wind gusts at close to 30 miles per hour greeted the players on Saturday and scores reflected it. Only 11 of the 84 players who teed it up in the third round broke 70.
'Out here it was swirling and going different ways,' said Andrade, who won this title in 1991. 'It was a very difficult day to play.'
Andrade began the third round two shots behind Singh and Howell, but Saturday was a day when par was a good score. He notched pars at his first four holes before a birdie at the par-5 fifth.
The second-round leaders and Jacobson moved to the top of the leaderboard, but struggled around the turn. Howell was 3 over par from the seventh through 13th holes and Jacobson began his descent down the board thanks to a missed 10-foot par save at the 10th.
Singh stayed in first after he bogeyed the eighth hole, but made pars through most of his second nine.
Andrade could not avoid bogey either as he dropped a shot at the 11th. He appeared to be in trouble at the par-4 13th as his approach sailed over the putting surface. Andrade chipped in from behind the green for a birdie to join Singh and Jacobson in the lead at minus-7.
Jacobson fell first as he bogeyed 13 and three-putted from 28 feet for another bogey at 14. Singh had a horrible lie at the 15th near a bunker and could no better than 30 feet from the hole. He two-putted that hole for a bogey, leaving Andrade alone in first.
Andrade padded his advantage with a 9-foot birdie putt at the 17th. He landed in a bunker with his second at the par-5 closing hole, but blasted out to 14 feet. He could not convert the birdie putt, but when Singh failed to eagle the last, Andrade took the 54-hole lead for the fourth time in his career.
Andrade won this title in 1991 after capturing the Kemper Open the week before. His last victory on the PGA Tour came at the 2000 event in Las Vegas, but the 42-year-old thinks he knows the formula to revisiting the winner's circle.
'I know you have to get the ball in the hole,' said Andrade. 'I'm going to go out (Sunday) and hold my emotions and think about when I won here in '91. If it's my day, it's my day. I'm looking forward to the challenge and can't wait to play.'
Singh mixed four bogeys and three birdies, including one at the last, to get within one of the lead. Singh, who won this title twice, has not won on tour since last year's Buick Open at the end of July.
Scott, who has finished in the top-four in his last three starts on the PGA TOUR, was even on his round through 13 holes before draining a 21-foot birdie putt at the par-3 14th.
He got to 7 under par with 13-foot birdie putt at 17 and could have matched Andrade in the lead, but his 7-foot birdie try at the last stayed above ground.
Ian Poulter posted the lowest round on Saturday with a 6-under 65. He is knotted in seventh place with Stuart Appleby (66) and Luke Donald (71) at 5-under-par 208.
Mathew Goggin (68), Joey Sindelar (73) and Graeme McDowell (71) share 10th at minus-4.
Reigning Masters champion and PGA Championship winner Phil Mickelson only managed an even-par 71 on Saturday and is part of a group tied for 22nd at 2-under-par 211.