EF0 tornado, Hartranft to Worcester, Pennsylvania, August 4, 2020

1. EF065 to 85 mphthis tornado

   Light damage. Surface peeled off some roofs, gutters and siding damaged, branches broken, shallow-rooted trees pushed over.

2. EF186 to 110 mph

   Moderate damage. Roofs badly stripped, mobile homes overturned or badly damaged, exterior doors lost, windows broken.

3. EF2111 to 135 mph

   Considerable damage. Roofs torn off well-built houses, frame homes shifted on their foundations, mobile homes destroyed, large trees snapped or uprooted, cars lifted off the ground.

4. EF3136 to 165 mph

   Severe damage. Whole stories of well-built houses destroyed, large buildings badly damaged, trains overturned, trees debarked, heavy cars lifted and thrown.

5. EF4166 to 200 mph

   Devastating damage. Well-built houses leveled, structures with weak foundations moved some distance, cars thrown and large missiles generated.

6. EF5over 200 mph

   Incredible damage. Strong frame houses swept off their foundations, car-sized missiles thrown more than 100 meters, steel-reinforced concrete badly damaged, high-rise buildings deformed.

7. Unrated

   The survey recorded a tornado but could not put a number on it, most often because it crossed open country and damaged nothing a rating can be read from.

Rating

EF0

Date

August 4, 2020

Touchdown

10:44 AM EDT (14:44 UTC)

Lifted

10:50 AM EDT (14:50 UTC)

On the ground

6 minutes

Path length

3.1 miles (5.1 km)

Path width

200 yards (183 m)

Deaths

0

Injuries

0

County

Montgomery County

Touchdown point

40.162, -75.332

Lift-off point

40.201, -75.362

Record number

2008040844-01

Tropical Storm Isaias brought high winds, heavy rain, several tornadoes, and coastal flooding to the mid-Atlantic region, becoming the most impactful tropical cyclone to impact most of the region since Sandy in 2012. Flash flooding as a result of heavy rain caused two direct deaths from this event...one in Lehigh County and the other in Montgomery County.

An EF0 tornado occurred in Worcester Township in Montgomery |County, Pennsylvania as Tropical Storm Isaias moved northward |along the East Coast of the United States. With southeastern |Pennsylvania being in the northeastward, right front quadrant, the|tornado and parent storm moved in an unusual northwestward |trajectory ahead of the main center of the tropical storm. An area|of circulation tightened in a strong cell within a rainband in |southeastern Montgomery County. As this circulation tightened, a |brief tornado formed near the intersection of Brindle Court and |Township Line Road in Worcester Township, where a few small trees |were downed in a small residential subdivision. From here, the |tornado continued its northwestward trajectory through the |township, downing trees along Potshop Road. The circulation may |have lifted with the path being somewhat discontinuous. A somewhat|denser area of trees were downed as the tornado moved across |Valley Forge Road and northwestward along Heebner Road. Several |tree tops were sheared off in addition to several utility poles |being pushed over along Heebner Road near the intersection of |Shefley Lane. The tornado continued northwest from here, |eventually downing several hardwood trees along Hollow Road. One |tree brought down several utility lines as it fell. From here, the|tornado lifted with only a few other trees being downed a little |ways from Hollow Road in a small wooded area.

From NOAA NCEI's Storm Events Database, the narrative the local forecast office wrote for Storm Data.

No tornado warning for this county appears in the archive as in force at the moment the tornado touched down. One was issued for the county at another hour that day.

The county was under a tornado watch, issued at 11:23 UTC and running to 17:11 UTC.

Every warning and watch covering the touchdown point that day, from the Iowa Environmental Mesonet's archive of National Weather Service products. Lead time is measured from the issue of the warning in force to the touchdown time in the database, both of which were recorded to the minute by different people.

The Storm Prediction Center had this point in a Slight Risk, with a 0.05 chance of a tornado within 25 miles. The outlook in force was issued at 12:04 UTC.

SPC's Day 1 convective outlook as it stood when the tornado began, read at the touchdown point. The same archive is on the radar archive.

The radiosonde launches on either side of the tornado, from the nearest station that was launching then, drawn and analyzed the way Storm Lab does: the same diagram, the same parcel and shear definitions SPC's mesoanalysis uses.

The Philadelphia radar (KDIX), 84 km away, was scanning. The volume nearest the touchdown began at 14:44 UTC.

Open the radar archive at this moment, over the track

Reflectivity and velocity, decoded from the Level II archive in the browser. Volumes take a few seconds to open the first time.

Local storm reports within 60 km of the path, in the three hours either side.

From the Iowa Environmental Mesonet's archive of National Weather Service local storm reports.

The live radar over the trackEvery 2020 tornado in PennsylvaniaEvery tornado in Pennsylvania since 1950Warnings in force in Pennsylvania nowThe forecast where you are

30 more were confirmed in the United States that day.

Ratings are the survey's, read off the damage rather than measured; the rating scale is above. Tornado counts rise through the record as reporting improved, so a year in the 1950s is not comparable with one today except for the strongest tornadoes, which were always noticed.

NOAA Storm Prediction Center tornado database, 1950-2025, the official record kept by NOAA's Storm Prediction Center.