Tenacity of summer's heat blisters the record

Posted: September 01, 2010

Sweat doesn't lie: Officially, this was the hottest summer ever in Philadelphia, and it wasn't even close.

The record was torched so overwhelmingly that it was in a league with what happened this winter, when Philadelphia's snow record fell by more than a foot.

The average daily high this summer, 88.7, was the highest ever.

In fact, it has been remarkably hot just about everywhere east of the Mississippi, and meteorologists say that could be adding volatility to the hurricane-primed Atlantic, where Earl is fomenting waves of concern along the Mid-Atlantic coast.

Although computer models continue to keep it offshore, Earl could generate drive-by rains and tropical-storm gusts along the Delaware and Jersey coasts before scooting Saturday into the far North Atlantic. It also could leave the ocean in an agitated state, with rip currents persisting well into the weekend.

Late Tuesday, it appeared unlikely that rains would penetrate far enough inland to break the Philadelphia region's latest burgeoning dry spell.

While the Earl watch continues, the indefatigable and historic heat that began brewing in May is about to lap into September.

For the period considered the meteorological summer, June 1-Aug. 31, the average temperature of 79.7 was better than a full-degree Fahrenheit higher than the new runner-up, 1994.

Given the generally modest temperature ranges in summer, when the sun's energy is spread generously across the Northern Hemisphere, a 1-degree difference between the No. 1 and No. 2 years is remarkable.

"That's pretty significant statistically," said Gary Szatkowski, the meteorologist in charge of the National Weather Service office in Mount Holly.

In 138 years of record-keeping, 1 degree is by far the biggest difference between any one year and the next-warmest one.

Consider that 1995 edged 1994 by 0.3, which was only 0.1 warmer than 1993.

What has been most impressive about this heat this year has been the tenacity. Sunday broke a stretch of eight straight days in which the official high had fallen short of 90 - the longest streak of the summer.

And heat has blistered the entire East. July was among the 20 warmest in every state east of the Mississippi River except Indiana, where it was No. 21. It was the warmest in Delaware, second-warmest in New Jersey, and No. 12 in Pennsylvania in 116 years of records, according to the National Climate Data Center.

All the heat coming off the land might be contributing to the record-high, hurricane-friendly ocean temperatures in the North Atlantic, said Jeff Masters, a meteorologist with the popular Weather Underground site.

The widespread Eastern warmth represents a reversal of the winter upper-air pressure pattern, meteorologists said. In winter, the pattern favored cold and snow in the East; in summer, it flipped to favor heat. What the patterns had in common during the two seasons was persistence.

Missing this summer were those fronts that allowed cooling sea breezes to rout the heat occasionally in the Philadelphia region, said Henry Margusity, a meteorologist with AccuWeather Inc., the private service in State College. "We didn't have any of the easterly flow days," he said.

The pattern change is related to the profound changes over vast expanses in the tropical Pacific, where sea-surface temperatures have dropped dramatically as a warm El Niño event has yielded to its cool opposite, La Niña.

Margusity said he expected generally warm and pleasant conditions to continue into the fall, but in the meantime, the East Coast has been confronting its first hurricane threat of the season.

"I'm counseling people to pay attention," said the Weather Service's Szatkowski. It could be a scary period for North Carolina, and along other East Coast beaches, it could be a rough period for the lip muscles of whistle-armed lifeguards.

Earl should be well past New Jersey on Saturday, but the ocean might not realize it right away.

Said Szatkowski: "It may take a day for two before the ocean gets back to normal."


Contact staff writer Anthony R. Wood at 610-313-8210 or twood@phillynews.com.

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