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Tornado in Delaware during Isaias was on the ground 29.2 miles, a new state record

It was one of the 37 tornadoes spawned by the tropical storm, including three in Delaware and nine in Maryland

(National Weather Service)

From the Carolinas to Connecticut, Tropical Storm Isaias unleashed more than three dozen tornadoes as it swept up the Mid-Atlantic coast one week ago. Among them was a tornado in Delaware, which traveled the greatest distance in the state on record.

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Most tornadoes spawned by tropical storms and hurricanes are quick-hitting and weak, but Isaias’s defied the rule. One deadly twister in North Carolina rated EF3 on the 0-to-5 scale for intensity, while several others spent tens of minutes on the ground, carving lengthy paths of damage.

Delaware’s record-breaking tornado tracked from its capital Dover to Middletown — some 29.2 miles away. That path length more than doubles the previous record for a tornado in Delaware of 13 miles, which stemmed from a twister in New Castle County on June 7, 1988.

The tornado last week first touched down about two miles southwest of Dover Air Force Base in southern Dover around 8:55 a.m. near the Eagle Meadows Apartment Homes.

The very strong area of rotation that produced the record-breaking tornado triggered a warning at 8:56 a.m.. A minute or two later, that tornado hit structures and lofted debris more than 10,000 feet into the air.

By 9 a.m., debris was being carried to about 15,000 feet as the tornado prepared to cross Highway 13 near Cheswold in the vicinity of a Walmart. The tornado then blew off a few sections of roof from William Henry Middle School.

Radar data then shows the tornado continuing north-northwest and striking Smyrna, where a Delaware Department of Transportation weather station recorded a 96-mph wind gust. At least one garage was destroyed, with considerable roof damage to a number of homes and trees uprooted.

The most severe damage involved a home, which lost an entire exterior wall. The corner walls of another structure were removed on its second floor.

The twister also impacted Townsend and Middletown, with a debris signature continually visible. The National Weather Service believes the tornado path may have even extended into Cecil County, Md., but damage was more sporadic.

Maximum winds in the tornado were estimated at 105 mph. No injuries were reported. The lack of casualties is fortunate considering the storm’s path parallel to and over two major roadways.

Delaware has only recorded two tornado fatalities dating back to 1950, both in a narrow F2 that briefly touched down about 12 miles west of Dover on July 21, 1983.

Isaias spawned a tornado that destroyed a Maryland woman’s home. One thing helped save her life.

Tornadoes associated with tropical storms and hurricanes move rapidly, and are usually erratic in nature and touch down for only a few moments. The fact that Delaware’s longest-traveling tornado on record appeared during a tropical storm is a testament to the unusual ferocity of Isaias as it traveled up the Atlantic coast.

Tropical cyclone-related tornadoes are born from a storm system’s extreme wind shear, or change of wind speed and/or direction with height. The thunderstorm feeder bands that pivot into tropical cyclones are otherwise not overly strong or tall, but they experience a serious twisting force — causing them to rotate and produce tornadoes.

The Delmarva Peninsula experienced nine confirmed tornadoes last Tuesday: three in Delaware, and six in Maryland. In addition three more tornadoes were confirmed in Southern Maryland, on the west side of the Chesapeake Bay, for a total of nine in the state.

Weather Service confirms three tornadoes in Southern Maryland associated with Isaias

Elsewhere, one tornado occurred in Connecticut, two in southeast Pennsylvania; two in New Jersey; seven in southern Virginia, mostly in the Tidewater; 12 in North Carolina; and one in South Carolina.

In all, the National Weather Service has confirmed 37 tornadoes occurred in Isaias.

The three twisters in Delaware from Isaias tripled its average yearly tornado output.

Jason Samenow contributed to this report.