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EF1 tornado in Lehigh County, Pennsylvania
Tornado July 29, 2021 · Lehigh County, Pennsylvania
NOAA records this tornado county by county. Its path ran through Berks County → Lehigh County; the totals above are for the whole tornado.
The path drawn at its surveyed width of 90 yards (0.05 mi) — zoom in and the swath grows to true scale. Other tornadoes recorded nearby that day are shown faint.
What the National Weather Service wrote
The tornado which began in western Albany Twp, Berks County, continued into Lehigh County. It tracked between between Kunkels Mill Rd and Red Rd near the far
southern tip of Lynn Twp. Mostly minor crop and
tree damage was observed in this area, but with a continued clear
convergent pattern. A resident on Red Rd filmed the tornado as it
passed to his south. The tornado passed through an open field before
crossing Rhoads Rd, where tree and minor roofing damage were
sustained. East of Rhoads Rd, a number of trees were snapped and
uprooted as the tornado approached New Smithville Rd. The tornado
crossed Golden Key Rd, uprooting a few more trees, before
dissipating in a field prior to reaching Loch Valley Rd in
Weisenberg Twp. The extent of tree damage both near the start of the
path in Berks County and in the New Smithville Rd area merited an EF1
rating.
The wider storm
A strong shortwave trough moved east-southeastward out of the Great Lakes region on July 29. An associated, strengthening surface low also tracked out of the Great Lakes and into upstate New York. A warm front associated with this low moved through most of New Jersey and eastern Pennsylvania during the late morning and early afternoon hours. This front, combined with the remains of widespread convection to the west from the previous overnight and morning hours, brought significant cloud cover to the eastern mid-Atlantic for much of the day on the 29th. This was mainly in the form of mid and high level cloud cover, however, and temperatures still warmed to near seasonal levels behind the warm front, allowing moderate to strong instability to build. Meanwhile, the robust surface and upper level disturbances approaching the region brought both strong forcing and unseasonably strong wind shear. By mid-afternoon, an unusually favorable convective environment existed over eastern Pennsylvania and New Jersey.
The result of this environment was a rare tornado outbreak across the area. Initially, during the mid-afternoon hours, mixed convective modes over east-central Pennsylvania produced a couple instances of damaging wind and brief tornadoes as storms attempted to overcome cloud cover and some light stratiform rain in the area. With time, as storms moved into better instability and a less contaminated environment over far eastern Pennsylvania and New Jersey, they took on more supercellular structures. Multiple cyclic supercells would go on to produce several tornadoes, three of them strong (EF2+) over eastern Pennsylvania and New Jersey. Convection persisted past the sunset hour with little to no loss in intensity due to the strong forcing. The only thing that put an end to the outbreak was the coastline, as storms moved offshore towards 9 to 10PM local time. Even offshore, one supercell continued to exhibit strong rotation and likely produced a strong waterspout for tens of miles over the Atlantic.
Fortunately, and miraculously, no serious injuries or loss of life occurred as a result of this outbreak. With the passage of a cold front late on the evening of the 29th, cooler, drier, and much less active weather would grace the region for several days as clean-up efforts began.
Began near Stines Corner (40.6151, -75.7965).
Other tornadoes from the same storm system
4 more tornadoes the National Weather Service filed under this storm episode.
Source: NOAA Storm Events Database, event 965609. Narratives are written by the National Weather Service forecast office that issued the report.
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