Strong storms are possible in Philly Thursday, but they won’t have anything to do with Arthur

It would have nothing to do with Arthur, which on Wednesday became the first named storm of the Atlantic hurricane season, but the Philly region may be in for tropical-storm force gusts and strong thunderstorms Thursday.

Even if the rains don’t come — and on Wednesday, the storm odds were close to 50-50 — wind gusts to 40 mph are possible during the afternoon, said Alex Staarmann, meteorologist at the National Weather Service in Mount Holly, “quite unusual for June.”

Not so unusual these days would be the forecast high, in the low to mid-90s, which would mark the 14th time this year that official readings in Philly had reached 90 degrees or higher. That is about half the average total for an entire year.

But this heat will be more of a ripple than a wave, and the outlook for the holiday weekend is looking spectacular.

As a front approaches, winds from the southwest are expected to gust to 20 mph during the morning and 30 to 40 mph in the afternoon.

While the winds are all but a certainty, it was unclear if any strong storms would pop Thursday. If they did, the best estimate would be mid- to late afternoon, and they could be nasty.

“The environment is favorable for damaging winds if anything does develop,” Staarmann said.

“The biggest question is how widespread the storms are going to be,” he said.

Such uncertainty is standard fare with thunderstorm threats this time of year, said Rich Thompson, forecast operations branch chief at the government’s Storm Prediction Center, which would have to make a call on posting severe storm watches.

With so many moving parts and micro-features such as terrain involved, predicting the behavior of small-scale storms is “incredibly complicated,” he said, and on some days clues are frighteningly lacking.

And while observations have improved immeasurably in recent decades, “we still aren’t observing most of what’s there,” he said. Land-based surface observations are far more plentiful than those over the oceans, which cover 70% of the atmosphere, and in the upper atmosphere, where the weather is manufactured.

Even if the atmosphere were perfectly measured, he added, meteorologists would still have to contend with the fact that the physics involved in forecasting are not completely understood.

As for Arthur, knighted with a name by the National Hurricane Center at 11 a.m. Philadelphia time Wednesday as it matured off the southeast Texas coast, it is forecast to deluge portions of the Gulf states.

Then it is due to head out to sea before it could have anything to do with Philadelphia or the Jersey Shore, which is likely to be a popular destination this weekend.

For Friday, Juneteenth; Saturday; and Sunday, the beginning of the astronomical summer, highs are expected in the mid-80s with sunny days and no threat of showers until early Monday.