NASCAR's longest race to largely escape rain on Sunday night

While there can be a passing shower or thunderstorm, the steadiest rain targeting Charlotte, North Carolina, is expected to hold off until after Sunday night's Coca-Cola 600.

Memorial Day weekend is one of the biggest race weekends of the year, featuring the world-famous Indianapolis 500 on Sunday afternoon followed up by NASCAR's longest race of the season on Sunday night.

The 600-mile race is held at Charlotte Motor Speedway with the green flag set to wave at 6:18 p.m. EDT, Sunday.

In this photo taken with a fisheye lens a rainbow forms as the sun sets after a storm caused a rain delay during the NASCAR Cup series auto race at Charlotte Motor Speedway in Concord, N.C., Sunday, May 28, 2017. (AP Photo/Mike McCarn)

Rain has already disrupted activities at the track this weekend.

"Rain canceled Saturday's opening Monster Energy NASCAR Cup Series practice as teams prepared for Sunday's Memorial Day tradition, the Coca-Cola 600," NASCAR said.

Saturday's NASCAR Xfinity Series race also saw rain delays two times, the first time leading to a caution and the second forcing the race to be put on hold for over an hour.

It is looking likely that much of the Coca-Cola 600 will be dry after concerns earlier in the week that rain may play a bigger role in the race. However, it will still be a close call whether or not a shower or thunderstorm passes through during the race.

"If a thunderstorm does move through the Charlotte region, it will likely lead to a delay until it is safely gone," AccuWeather Meteorologist Tyler Roys said.

Any shower or thunderstorm in the region will be spotty in nature, allowing many places to stay dry.

"Race fans and crews will have to monitor cell phones and other devices for any lightning alerts," AccuWeather Senior Meteorologist Kristina Pydynowski said. "While a distant thunderstorm may not halt the race, it could pass close enough to produce a lightning strike near the speedway."

The chance for rain will increase as the race progresses as tropical moisture from Alberto advances northward into the Charlotte area.

"Rain from Alberto is expected to move in after the race, mainly after midnight and continue into Monday," Roys said.

When inclement weather disrupts a race, NASCAR officials have the option to end the race early as long as half of it has been completed.

For Sunday's race, this means that at least 200 of the 400 laps need to be completed before officials can call the race.

If the red flag flies before the 200-lap benchmark, NASCAR has two options. If the rain is brief, the race can be put on hold until conditions improve and the track can be dried. However, if the rain shows no signs of letting up, the race will be postponed and resumed the next day.

The weather has impacted several NASCAR races this year, including a late-March race in Martinsville, Virginia, that was postponed due to snow.

Most recently, the threat of rain caused the start time of the May 6 race at Dover International Speedway to be moved up to ensure the race would be completed before the arrival of heavy rain.

This precaution may be taken on Sunday evening if it appears as if heavy rain or thunderstorms will move into Charlotte before the race is projected to be over.

In addition to causing delays, heavy rain can wash the track surface and change the way that cars handle before the rain.

Drivers and fans will head to the Tricky Triangle next weekend as the season heads to Pocono Raceway.