Atwal, who shot 76 on the first day, struck five birdies and a couple of double bogeys in the second round.
Atwal finished at 146, while the cut came at 138. Atwal had birdies on the third, sixth, 12th, 15th and 18th and he had double bogeys on the ninth and 16th.
Meanwhile, Jonas Blixt carded a second successive seven-under 64 to take a share of the lead after 36 holes. He is at 128, the same as Zimbabwean Brendon de Jonge (62, 66) at 14-under.
Both are winless on the PGA Tour.
Ryan Moore who equalled the TPC Summerlin course record with a 61, was a stroke back after a second round 68. Daniel Summerhays (63) and Tim Herron (68) were at 11-under.
Vijay Singh (66), Nick Watney (66), Chris Kirk(68) and Joh Huh (69) are at 10-under. Singh and Watney shot 66, Kirk had a 68, and Huh a 69.