The National Hot Rod Association has no plans to postpone its big weekend races at Lucas Oil Raceway in spite of forecasts calling for possible heavy rain caused by the remnants of Hurricane Isaac.

The NHRA Mac Tools U.S. Nationals, the association’s largest and most prestigious annual event, typically draws about 35,000 spectators daily. Qualifying sessions at the strip in Clermont west of Indianapolis run Friday through Sunday with final eliminations on Monday.

The National Weather Service predicts that rain and storms from Isaac will arrive in the metropolitan area after 8 p.m. on Friday and possibly continue through Monday.

The NWS forecasts 2 inches to 4 inches on Saturday, when potential for the heaviest rainfall is greatest. Showers and thunderstorms likely will continue through Sunday, with a 40-percent chance of rain Monday.

“Unlike Katrina, which was here one day and out the next, this one looks like it’s going to linger for two to three days,” said Al Shipe, a service hydrologist for the weather service.

Another big Labor Day weekend event, the Rib America Festival that runs Friday through Monday at Military Park in downtown Indianapolis, will take place rain or shine. Safety shelters will be available near the stage, promoters said.

If the races are postponed this weekend, it wouldn’t be the first time. The California-based NHRA was forced in 2003 to finish its Nationals the weekend following Labor Day due to persistent showers. That year, 7.2 inches fell, a record for Labor Day.

But the association is confident this year’s event will run as scheduled, NHRA spokesman Scott Smith said.

“Our plans right now are, we’re going to go racing,” he said. “If it does rain, we can work to get the track dried and get it back to racing condition.”

Lucas Oil Raceway also is equipped with lights, Smith said, so cars can run after sunset if necessary.

The NHRA expects large crowds, though the association is uncertain about ticket demand. Many purchase tickets the day of the races, Smith said.

Fans can visit www.nhra.com or www.lucasoilraceway.com for weather updates.