Reilly Rankin shot a 66 to finish alone in second place at 7-under-par 137. Cristie Kerr was one shot further back at 6-under-par 138 while Rosie Jones took fourth place at 5-under-par 139.
Rosales struggled to a bogey on the opening hole of the Palmer Course at Turtle Bay Resort Golf Club but responded with a birdie at the very next hole. Rosales then chipped her third shot within 2 feet of the hole for a tap-in birdie at the par-5 third under windy conditions.
The 26-year-old bogeyed the fifth but played her approach to 18 feet for a birdie at the par-four seventh.
Rosales fell off the pace with back-to-back bogeys starting at the par-4 10th but began to work her way back with a birdie at the par-4 14th. Rosales then birdied the 16th and hit her second shot inside 6 feet for a birdie at the par-4 17th.
At the par-5 18th, Rosales knocked her third shot within 15 feet of the cup and drained the putt to carry a two-shot edge into the final round.
'Today just played different,' said Rosales. 'The whole day I was in between clubs and I just couldn't figure it out. Finally in the end, I hung in there and finished strong.'
Rankin collected three birdies on the front nine but faltered with a bogey at the par-4 10th. Rankin countered with a birdie at the 12th and ran off back-to-back birdies from the 14th to climb to minus-6.
The 25-year-old then sank a 14-footer for a birdie at the par-5 18th to finish within two of Rosales.
'You have to be patient and take your time with it because a gust of wind can make a change,' said Rankin. 'It can make a dramatic difference.'
Michelle Wie continued to play well in front of the hometown fans and ran off a trio of birdies over her first nine holes to make the turn at 5 under.
The 15-year-old amateur bogeyed two straight from the 10th but converted a 9-foot putt for a birdie at the last.
'Tomorrow, I just have to focus on my putting and make all of my crucial putts that I have to make,' said Wie, who shot a 70. 'I have to keep the ball in play and try to give myself a lot of birdie opportunities.'
Wie was joined by Lorena Ochoa and Hee-Won Han at 4-under-par 140. Nicole Perrot finished alone in eighth place at 3-under-par 141.
Carin Koch, Angela Stanford, Tina Barret and Michelle Estill shared ninth place at 2-under-par 142.
The 36-hole cut came at 4-over-par 148 with 75 players qualifying for the final round.