Olympic marathon trials bring mystery to Los Angeles

This weekend will finally answer the questions that have surrounded the U.S. Olympic marathon trials as the nation’s best runners gather in Los Angeles to decide who will go to the 2016 Summer Games.

The uncertainty begins with unseasonably warm weather -- Saturday’s forecast calls for temperatures in the low 80s, which could have an effect on times.

“I think optimum for almost all the marathoners would be in that 40-degree range,” said Shalane Flanagan, the defending champion in the women’s event.

The men’s field will look unfamiliar with the retirement of top runner Ryan Hall and the withdrawal of Abdi Abdirahman, a four-time Olympian. At 40, Meb Keflezighi will be the only competitor in the field who represented the U.S at the last Olympics.

Several newcomers -- including Galen Rupp, an Olympic silver medalist at 10,000 meters -- will attempt to fill the void.

“If those guys are in great condition, they could hit a home run and be big factors,” Keflezighi said.

The final variable will be the course itself, which starts and ends near Staples Center. It will feature an initial 2.2-mile loop that extends to a 6-mile loop, twisting past downtown, the USC campus and the Coliseum.

“You’ve got to make the turns smart and effective,” Keflezighi said.

The men start at approximately 10 a.m., with the women following about 15 minutes later. Both races will end between noon and 1 p.m.