On November 2, 2018 A strong squall line (QLCS) moved through southeastern Pennsylvania. Strong rotation at places along the leading edge of the line (not uncommon in these systems) resulted in the Mt. Holly NJ NWS Forecast Office to issue two tornado warnings. Although no tornadoes touched down, there was strong rotation as seen in the images below. Despite the tornado warnings, there was no lightning observed as the line move through the area.
This image shows AWIPS II (left panel), and GR2 Analyst (right panel) Storm Relative Motion displays from the Fort Dix NJ Nexrad radar (KDIX). The right panel clearly shows rotation near Limerick PA (red and green next to each other).
GR2 Analyst screenshot showing the strong couplet that generated the tornado warning.
The arrows in the right panel of this image show areas of possible rotation along the leading edge of the squall line.
GR2 Analyst screenshot showing the multiple areas of rotation.