The storms came after fears of a derecho, a widespread violent windstorm, prompted aircraft to evacuate from the EAA AirVenture air show in Oshkosh, Wis., on Tuesday evening. Storm tops towered to 70,000 feet as severe storms rolled through the area, though a derecho never formed.
The same instigating upper-air disturbance shifted east Friday, stirring up an outbreak of rotating supercell thunderstorms that stretched from New York City to the Virginia’s Hampton Roads area. Severe thunderstorm and tornado watches spanned from the Midwest to the Atlantic coastline.
The National Weather Service received more than 100 reports of severe weather between the Ohio Valley and the East Coast.
The National Weather Service in Mount Holly, N.J., which serves eastern Pennsylvania, most of New Jersey, Delaware and much of the Delmarva Peninsula, was planning to survey at least a dozen swaths of damage.
The worst damage occurred at a car dealership in Pennsylvania’s Bucks County northeast of Philadelphia. The structure lost its roof, with insulation strewn about the parking lot. Vehicles were flipped. The Faulkner Buick GMC and Volvo dealership suffered serious damage; five people were injured.
The National Weather Service confirmed it as an EF3 tornado on Friday afternoon, with winds in the 136 to 165 mph range. The most serious damage occurred to the dealerships and at an adjacent mobile home park. It’s the strongest tornado to hit the state of Pennsylvania since an F3 hit Campbelltown in Lebanon County in 2004.
The state of New Jersey hasn’t had an F3/EF3 tornado since October of 1990, when a funnel injured 8 and caused $2.5 million in damage in Somerset County. It’s possible that one of Thursday’s twisters in New Jersey ends up an EF3.
The first storms popped in western Pennsylvania and West Virginia around 1 or 2 p.m., a few of them rotating and producing funnel clouds. Simultaneously, a lone storm formed over the Delmarva Peninsula. Storm chasers reported a rotating wall cloud and eventually a funnel cloud just before 3 p.m.; a tornadic waterspout touched down shortly thereafter in north Bethany Beach. The mammoth funnel loomed close to the coastline and captivated bewildered onlookers, though no damage was reported.
A barrage of rotating supercell thunderstorms cropped up west of Interstate 95 during the afternoon hours, the most severe forming in eastern Pennsylvania. One tornado warning hoisted for Hunterdon and Mercer counties in New Jersey and Pennsylvania’s Bucks County at 5:51 p.m. warned of a “confirmed large and dangerous tornado.”
“That [supercell] actually started back in northwest Bucks, so that started at around 5 o’clock, and then tracked through Bucks County,” said Brian Haines, a meteorologist at the Weather Service in Mount Holly. “Then it started to curve to the right, and that basically went down the east side of Bucks County and went to the county line of Mercer. We’ve been getting sporadic damage reports all the way down to the Monmouth-Mercer County line. That lasted through about 7:30.”
The northern tip of Monmouth County stands across the bay from Staten Island; the New York City metro area was fortunate to escape without a more significant event.
Haines mentioned the storm’s rightward curve. “Right movers” always are a red flag for meteorologists. Their deviant motion usually enhances low-level helicity, or spin, enough to boost the odds of tornado formation.
“We had been considering [a tornado emergency] in our back pocket,” said Haines, referring to the most dire type of alert the Weather Service can issue. Tornado emergencies are reserved for the most high-end tornado threats that are likely to result in fatalities. A tornado emergency has never been issued in New Jersey or the Northeast.
“A situation when we’d consider it would be a devastating tornado causing damage in an urban area with loss of life looking likely,” Haines said. “We already had that ready to go.”
Instead, his team opted for a “particularly dangerous situation” tornado warning, noting that debris had been spotted on radar. The beam was striking objects with low correlation coefficient, meaning they were spiky, oblong or not otherwise something that would be associated with typical raindrops or strictly precipitation processes.
Radar even revealed debris fallout near Trenton, N.J.; it’s likely that leaves, sticks and other small lightweight items fell around the state capital.
As that storm was winding down, another one began terrorizing Bucks County again about 15 miles to the south of the first storm’s path.
“That one started about 6:30 and then continued on till about 7:30ish or so when the tornado signature ended,” Haines said. That tornado is the one that slipped south of Trenton and heavily damaged the car dealership.
“Another supercell south of it went all the way to Ocean County. … That went to the coast. That was a third one,” Haines said. That supercell exhibited a clean, classic “hook echo” with extreme rotation and turbulence in the spinning updraft, as impressive, if not more so, than many of the strongest that developed across traditional Great Plains Tornado Alley this year.
That storm produced damage near Long Beach.
“We actually got ping-pong-ball-size hail at the NWS office” in Mount Holly, Haines said.
His office dispatched five survey teams to investigate a dozen strips of reported damage across their county warning area. Other tornadoes spun up along the Ohio-Pennsylvania border.
“It’s going to be a long day,” Haines said Friday morning.
Historically the most prolific tornado events in Pennsylvania and New Jersey occur in July. In the Deep South and on the Plains, tornadoes are most common in the springtime during the annual clash between winter and summer air masses.
It’s been a particularly active year for severe storms in the northern Mid-Atlantic states. The Weather Service office in Mount Holly has issued more tornado warnings than the Weather Service office in Norman, Okla.
Meanwhile, additional severe weather lashed areas near the nation’s capital. A tornado warning was issued west of Baltimore, but no tornado touched down. Around 6 p.m., a lone, isolated rotating supercell developed south of D.C. in north-central Virginia, tracking south as another “right mover.”
It produced hail larger than two inches in diameter near Fredericksburg, Va., a rare “hail spike” appearing on radar where large, wet hail reflected the radar beam to the ground and then to the receiver. That’s ordinarily a surefire sign of destructive hail. Winds stronger than 80 mph also accompanied the storm as it blasted southeast into the Hampton Roads region.
Storm chasers in the thick of the storm think it may even have contained a rain-wrapped tornado. The Weather Service planned to survey damage around Fredericksburg and Stafford County on Friday to determine if a twister actually touched down.
In the meantime, more-pleasant weather is likely over the weekend as a cooler, more refreshing air mass builds in. Highs in the 70s and 80s are likely for the next week across the Northeast with greatly reduced humidity.