Lightning injuries are rare, but an expert says the Parkway is an especially risky venue on July 4

In the grand casino of the atmosphere, scheduling outdoor events on July Fourth in the Philly region is almost always going to be a rolling of the bones.

And on the day Philadelphia and the rest of the national are holding a mass 250th birthday party, the odds may be dicier than usual, with thunderstorms and accompanying lightning possible Saturday afternoon and night, forecasters say.

July happens to be the peak month for lightning-bearing thunderstorms in Philadelphia, occurring every five days on average, and who doesn’t want to be outside on the Fourth?

As if record-challenging heat and an atmosphere that feels like syrup weren’t enough.

Lightning injuries and fatalities are rare — on average in the last decade, 20 people have been killed annually by lightning in the United States, according to the National Weather Service. But among outdoor events with large crowds across the country, Philly’s July Fourth concert would be among the riskiest for lightning, according to Stephen Strader, disaster specialist at Villanova University.

“It’s way up there, a lot higher than I thought it was,” he said.

The city is well aware of the atmosphere’s capriciousness, the potential risks in July, and the potential effects on the Parkway celebration and the World Cup match in South Philly and has developed safety protocols, said Jeffery Kolakowski, communications director for the Office of Emergency Management.

Unfortunately, for attendees and planners, predicting the when and where for thunderstorms remains elusive.

“There’s uncertainty of the when and where of the storms,” said Rich Thompson, branch chief and lead forecaster at the federal Storm Prediction Center, in Norman, Okla., the source of those severe storm and tornado watches. “It’s still one of the great frontiers of meteorology. It’s incredibly difficult.”

Readings soared to 97 on Wednesday, and the heat index shot past 105 in Philly as the atmosphere thickened in a hurry.

And it’s about to get thicker. The heat is forecast to peak Thursday and Friday with highs surpassing 100. It could cool down all the way to 99 on Saturday, said Matt Benz, senior meteorologist with AccuWeather Inc. Unfortunately that would indicate increasing volatility in the atmosphere.

High pressure though the atmosphere, the so-called heat dome phenomenon, has put a lid on convective storms, “but that starts to come off Friday into Saturday,” he said. That could lead to “ring of fire” thunderstorms, so named because they form on heat-dome edges. They can be especially nasty.

“We’re worried that something is going to be blowing up,” he said.

The storms could come in one bunch in the early evening and yield to a peaceful night, but they also could come in waves over a period of hours.

Even without strong storms — or storms not in the immediate vicinity of the festivities — lightning strikes are possible.

“Unfortunately that could be the biggest concern that day you’ve got lighting and people outdoors,” said Benz.

The chances of being struck by lightning are remote, about one in a million in a given year, according to the National Weather Service.

But they do happen: They’re what Strader calls “low probability events” with “high consequences.” In 2019, several people were injured when lightning struck at a PGA tournament in Georgia.

In 2014, a severe thunderstorm forced thousands of concertgoers at Philadelphia’s Made in America Music Festival to evacuate the Parkway for a short time that Sunday evening.

But for the most part, Fourth of July fireworks have been confined to the manmade kind.

In his analysis, Strader looked at thousands of outdoor events attended by 10,000 or more people, what he called “large outdoor public gatherings,” to calculate which ones would expose the most people to cloud-to-ground lightning strikes, taking into account location and time of year.

He found that both the Parkway and World Cup events in Philly this year would rank among the top 6%, using his criteria. The Parkway would be particularly problematic given the lack of shelter options.

All during the events the City’s Emergency Operations Center will be operating with a “play by play” from a National Weather Service forecaster, said Kolakowski.

In the event of lightning he said, “an evacuation of the area could be issued and people would be asked to leave the event ground in a safe manner and seek shelter.”

He said weather messages would be broadcast on screens, loudspeakers, social media, and text alert.

He added that people can get free event or safety alerts by texting CUPPHL or AMERICA to 888-777.

May they be unnecessary.