The 17-year-old, playing on a sponsor's exemption, shot an even-par 71 to put her at seven-under 135 after two rounds of play.
That was enough to maintain a one-shot overnight lead over nearest rivals Stacy Lewis and Angela Stanford, who were a shot back after 68s - the best rounds of the day on a wind-swept River Course in Williamsburg.
Jutanugarn started slowly, missing three short par putts early on, but the teenager regained her composure to roll in a 45-footer before having another two birdies to end the day on top of the pile.
Suzann Pettersen, winner in 2007, and Sandra Gal both had 69s to move into a tie for fourth in what were trying conditions.
"The wind's not dying down out there so it's going to be tough this afternoon," said Lewis, who completed her round early before the wind really picked up.
Pettersen said: "I like it when it's tough. It's very challenging. Like I said, you can't really back off. You can't really bail out. Once you decide on a club, you've got to hit the shot you're seeing, otherwise you could be three clubs short or two clubs long. For me, it just sharpens my focus a lot."
- Sports & Recreation
- Stacy Lewis
- Angela Stanford