The junior set a new school record with a time of 21 minutes, 45.59 seconds on the 5K (3.1-mile) course to finish 25th at the Aubrae Gunderson Invitational in Conyers on Sept. 29.
She followed that up with a third-place finish and a time of 22:58.46 at the Atlanta Public School Championship at Grant Park on Oct. 13, leading the Lady Warriors to the school’s first city title.
It has been a breakthrough season for Mabrey, whose average time was in the 28-30 minute range the last couple of years.
Mabrey has led a North Atlanta that has emerged as a team to watch with impressive performances at a number of meets, including a sixth-place team finish at the Aubrae Gunderson meet.
“MacKenzie has really come along this season,” North Atlanta community coach George Sanderlin said. “Her best time going into this season was about 28 minutes, but she ran over the summer and worked really hard to get better. She has a great work ethic and she is determined to get better.”