EF1 tornado, Waynesville to Millersburg, Pennsylvania, August 18, 2021

1. EF065 to 85 mph

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

2. EF186 to 110 mphthis tornado

   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

EF1

Date

August 18, 2021

Touchdown

6:31 PM EDT (22:31 UTC)

Lifted

6:37 PM EDT (22:37 UTC)

On the ground

6 minutes

Path length

5.5 miles (8.9 km)

Path width

150 yards (137 m)

Deaths

0

Injuries

0

Property damage

$20,000

County

Dauphin County

Touchdown point

40.451, -76.907

Lift-off point

40.524, -76.878

Record number

2108181631-01

7 damage points were recorded along this path by NWS CTP, in the Damage Assessment Toolkit the survey teams carry. The strongest indicator was rated EF1. The highest wind the damage implies is 105 mph.

• Plants in wheat field flattened, along with exhibiting convergent pattern.
• Few foot section of barn roof torn off.
• Several snapped and fallen trees.
• Numerous hardwood trees snapped and uprooted in heavily forested area.

Survey points are preliminary and are the raw material the published rating was built from. Source: NWS Damage Assessment Toolkit.

An EF-1 tornado touched down east of Halifax during the early evening of August 18, 2021. The tornado had estimated peak winds near 105 mph, a path length of around 5.5 miles, and a maximum path width of 150 yards.

The tornado began west of the intersection of Parmer Drive and Price Road in Halifax Township, where it tore off a few foot section of the roof of a barn. The path then continued north to northeast, crossing Powells Valley Road. A row of trees was knocked down in a circular (counterclockwise) pattern, with a densely populated grove of trees being snapped and uprooted in varying directions to the east of that location. This is where the EF-1 damage began, with an estimated peak wind speed of 105 mph. Farther northeast and north of Hoover Lane, another grove of trees was snapped and knocked down in numerous directions. This was the end of the EF-1 caliber damage, with the tornado continuing to track northeast producing EF-0 intensity damage. Just north of Ridge Road and west of Hershey Road, a wheat field had several individual plants flattened. Just north of that wheat field, the tornado briefly weakened. The tornado then reintensified as it moved across Millwood Drive, where several trees were uprooted. The tornado then lifted as it moved north of Millwood Drive.

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.

The county was under a tornado watch, issued at 15:37 UTC and running to 01:54 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 19:38 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.

Muir Aaf/Indiantown (MUI), 28 km from the path, in the two hours either side.

From the Iowa Environmental Mesonet's archive of airport observations.

The State College radar (KCCX), 105 km away, was scanning. The volume nearest the touchdown began at 22:30 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 2021 tornado in PennsylvaniaEvery tornado in Pennsylvania since 1950Warnings in force in Pennsylvania nowThe forecast where you are

6 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.