Felix St. Fort admits he got a bit carried away.

As the lead artist of a “Welcome back, Philly” ground mural on Benjamin Franklin Parkway, he created a design that required more than 100 subtly different shades of purple, blue, orange, and yellow. He was told he could cover the entire 33,000-square-foot parking lot inside Eakins Oval, below the Philadelphia Museum of Art, in heralding the city’s emergence from the COVID-19 pandemic. This was no time to hold back.

“They gave me the whole canvas,” the Mount Airy resident said. “So I went a little wild.”

Then came the rain. The skies cut loose at 1 p.m. Saturday, cutting short a public painting event that had been scheduled to last from noon until 3 p.m. Some of the colors ran a bit, but St. Fort, a staff artist at Mural Arts Philadelphia, said his resolve was undampened. He and other artists plan to clean up the runny parts and complete the mural throughout the coming week, finishing in time for the July 4 festivities.

“We’ll come back bright and early tomorrow and start attacking it,” he said.

If New York is known for Broadway and Chicago sings the blues, Philly does murals. So what better artistic medium for the city to signal its return to normal?

The mural arts program now boasts more than 4,200 artworks inside and outside buildings across the city, said executive director Jane Golden. Unlike most of the others, the new ground mural is designed to be temporary, likely to fade with exposure to the elements after a month or two. The program’s vertical murals, on the other hand, are coated with sealant and can last for decades.

Still, the city hopes the ground mural will have a lasting impact on public health. It is the largest of 40 temporary murals to be painted this summer as part of the Vax Up Philly campaign, in conjunction with the city Department of Public Health and Philadelphia Parks & Recreation. Most of the artworks will be located in zip codes with lower-than-average rates of vaccination against the coronavirus.

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“We want to do something that’s big and bold and inspiring,” Golden said.

St. Fort’s vivid design transitions from darker shades on one end to lighter hues on the other, suggesting a post-pandemic rebirth, Golden said.

“You really feel the transcendent power of art when you look at it,” she said.

Several dozen volunteers showed up Saturday, using rollers and brushes to start filling in the grids that St. Fort and his artist colleagues had mapped out in advance. Mayor Jim Kenney even took a turn before the rain started.

The weather was a setback for a vast project that covers three-fourths of an acre. But St. Fort was unconcerned. He will be joined in the coming days by fellow Mural Arts staffers, partners from other arts groups, and any volunteers who happen to come by.

“There’s no worries,” he said. “We’ll get it done.”