After a significant heatwave, a cold front approached the mid-Atlantic on July 1, 2021. A potent mid-level trough was also digging southward through southern Ontario and into the Great Lakes region, and a strong upper level jet streak was present downstream the trough axis, over the interior mid-Atlantic and northern New England. This strong upper level forcing combined with the approaching front and a lingering warm, moist air mass ahead of it caused widespread thunderstorm development on July 1. Storms occurred almost exclusively south of Interstate 78, in the environment of best instability. A number of storms became severe, taking the form of mainly linear and multi-cellular clusters but with some embedded supercellular characteristics. Straight line wind damage was the primary hazard, with a number of reports of downed trees and power outages due to winds. In addition, two confirmed EF-1 tornadoes occurred over southern Delaware. A remnant outflow boundary from earlier storms to the north, combined with sea/bay breezes in the area, likely caused a localized enhancement of low level wind shear and created a corridor of enhanced tornado potential. With the cold front remaining to the west, some storm activity continued into the overnight, but storm coverage and intensity gradually waned with the loss of daytime heating and the overturning of the atmosphere from earlier storms.

Thunderstorm Wind in SUSSEX, DELAWARE
From 01-JUL-21 16:19:00 to 01-JUL-21 16:19:00 (EST-5)
Location: STOCKLEY
Magnitude: 50.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Utility Company

Power poles and wires were downed near Morris Mill Rd. Time estimated from radar.

Thunderstorm Wind in SUSSEX, DELAWARE
From 01-JUL-21 17:32:00 to 01-JUL-21 17:32:00 (EST-5)
Location: BRIDGEVILLE
Magnitude: 50.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Utility Company

Several reports of trees and wires down near Route 18 southeast of Bridgeville. Time estimated from radar.

Thunderstorm Wind in SUSSEX, DELAWARE
From 01-JUL-21 15:53:00 to 01-JUL-21 15:53:00 (EST-5)
Location: GREENWOOD
Magnitude: 55.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Utility Company

Several reports of downed trees and wires northeast of Bridgeville. Time estimated from radar.

Thunderstorm Wind in SUSSEX, DELAWARE
From 01-JUL-21 16:18:00 to 01-JUL-21 16:18:00 (EST-5)
Location: PILOTTOWN
Magnitude: 56.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Measured at NOS gauge lwsd1 near Lewes.

Thunderstorm Wind in SUSSEX, DELAWARE
From 01-JUL-21 15:42:00 to 01-JUL-21 15:42:00 (EST-5)
Location: RELIANCE
Magnitude: 50.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Utility Company

Trees and power lines were downed near Woodpecker Rd. Time estimated from radar.

Thunderstorm Wind in SUSSEX, DELAWARE
From 01-JUL-21 15:53:00 to 01-JUL-21 15:53:00 (EST-5)
Location: BLADES
Magnitude: 55.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Fire Department/Rescue

Wires were downed on Hall St, Alder Ln, and near the intersection of Neals School Rd and Boyce Rd in Seaford. Time estimated from radar.

Thunderstorm Wind in SUSSEX, DELAWARE
From 01-JUL-21 16:09:00 to 01-JUL-21 16:09:00 (EST-5)
Location: SLAUGHTER BEACH
Magnitude: 70.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Measured by a personal weather station in very close proximity to an EF-1 tornado.

Tornado in KENT, DELAWARE
From 01-JUL-21 15:52:00 to 01-JUL-21 15:55:00 (EST-5)
Location: FARMINGTON
Tornado F-scale: EF1
Reported by: NWS Storm Survey

Wind damage was first observed near a residence on Farmington
Road, knocking down and snapping several trees in a narrow swath.
The tornado then continued over railroad tracks and a cornfield,
where a notable convergent pattern was observed. From there, the
tornado proceeded eastward toward the South DuPont Highway, but
not before causing damage to a business where metal roofing was
peeled off. Several snapped trees were also noted on the property.
Subsequently, the tornado crossed Gun and Rod Club Road where
another area of trees were downed, with numerous branches across
the roadway. South of Williamsville Road along Hogtown Road, a
residence was damaged when a tree fell on to the roof. On the
other side of the road, a corn field was present with a notable
divergent pattern observed. This damage, south of the tornado
track, was likely due to a RFD surge. The tornado then crossed a
large wooded area with damage again observed to a property on the
east side of the wooded area along Hunting Quarter Road. Numerous
trees were snapped on the property with damage also occuring to a
house due to a downed tree limb. Power lines were also knocked
down. Debris was then lofted towards a farm across Hunting Quarter
Road. The tornado then weakened and lifted just west of Deep
Grass Lane with only a few down branches being noted.

Thunderstorm Wind in KENT, DELAWARE
From 01-JUL-21 15:26:00 to 01-JUL-21 15:26:00 (EST-5)
Location: HARTLY
Magnitude: 50.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Utility Company

Tree limbs and wires were downed east of Hartly. Time estimated from radar.

Thunderstorm Wind in KENT, DELAWARE
From 01-JUL-21 15:42:00 to 01-JUL-21 15:42:00 (EST-5)
Location: PLYMOUTH
Magnitude: 50.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Utility Company

Several reports of downed tree limbs and wires north of Felton. Time estimated from radar.

Tornado in SUSSEX, DELAWARE
From 01-JUL-21 16:00:00 to 01-JUL-21 16:07:00 (EST-5)
Location: MILFORD ARPT
Tornado F-scale: EF1
Reported by: NWS Storm Survey

Damage was first observed near residences at the Cedar Beach Road
and McColley Road intersection. Here, several large branches and
trees were snapped. Further east along Cedar Beach Road, more tree
damage occurred across several residences with a couple of trees
having been uprooted. The tornado then uplifted part of a porch
roof to a residence on Shockley Road. Insulation that was
underneath the roof was blown across Shockley Road and adhered to
nearby homes. Insulation was also noted on all sides of the
affected residence. At the intersection of Shockley and Cedar Neck
Roads, a residence also had a large television antenna that was
bent 180 degrees down towards the ground. Further east on Mills
road, another residence observed multiple trees that were snapped.
One large branch fell on an outdoor shed causing it to collapse,
with other large branches falling on vehicles causing window
damage. Towards Fannies Way, additional EF-1 damage was noted with
a majority of roofing material lost to a pole barn along with two
enclosed trailers being overturned. Roofing material from the
pole barn along with tree branches were observed in the adjacent
corn field. The tornado then moved eastward into marshland and
proceeded towards the intersection of Bay Avenue and Slaughter
Beach Road. Another pole barn lost a majority of roofing at the
intersection with a small trailer having been overturned. Smaller
tree branches were then snapped as the tornado lifted near the
Delaware coastline. Interestingly, a nearby DEOS mesonet site
measured a peak wind gust of 62 mph near this endpoint.

Thunderstorm Wind in SUSSEX, DELAWARE
From 01-JUL-21 15:50:00 to 01-JUL-21 15:50:00 (EST-5)
Location: BLADES
Magnitude: 50.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Utility Company

Tree limbs and wires were downed near Craigs Mill Rd and Woodland Rd. Time estimated from radar.