EF1 tornado, Lone Pine to Eighty Four Arpt, Pennsylvania, June 23, 2017

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

June 23, 2017

Touchdown

3:21 PM EDT (19:21 UTC)

Lifted

3:23 PM EDT (19:23 UTC)

On the ground

2 minutes

Path length

3.0 miles (4.8 km)

Path width

250 yards (229 m)

Deaths

0

Injuries

0

Property damage

$60,000

County

Washington County

Touchdown point

40.104, -80.171

Lift-off point

40.101, -80.115

Record number

1706231321-01

Remnants of tropical storm Cindy interacted with a southward moving cold front in the afternoon of June 23rd. In addition to heavy rain and flooding concerns, especially with saturated antecedent conditions in several locations in southwest PA, severe thunderstorms were also possible. There were numerous reports of trees down across much of northern West Virginia, southwestern Pennsylvania, and even Garrett county, Maryland with reports of flooding in some of the same locations, as 2-4 inches of rain were reported through the evening. There also was enough low level shear to support a non-zero tornado threat, which did materialize across southwest PA and northern WV. One EF-1 tornado was confirmed in Washington county, PA, and two tornadoes, an EF-0 and EF-1, were confirmed in Monongalia county, WV. Fayette County, PA also declared a state of emergency.

The National Weather Service survey team confirmed a tornado near Lone Pine in Washington County, western Pennsylvania on June 23 2017. Damage was first encountered near Potato Run Road and Friends Road,where a swath of tree blowdown was noted. Large limbs were snapped, and hardwood trees were snapped or uprooted in this area. The swath continued uphill along Friends Road. Well-built structures did not seem to suffer direct wind damage at this point of the path, which narrowed and weakened upon surmounting the hill along Friends Road. The circulation then widened and intensified as it crossed Chestnut Ridge Road. Considerable damage to trees and structures was evaluated near Brush Run Road and Frazee Road. In this area, large hardwood and softwood trunks were snapped, entire trees were stripped of their branches and shingles were removed from several homes. A detached garage suffered uplift of a portion of its roof, and a large, downwind-facing porch roof was removed from a home. Deck furniture was lofted and blown into properties several homes down |crosswind. The path continued east-southeastward across Sunedecker Road, |where trees were snapped or uprooted. Damage along the remainder of the path thereafter appeared limited to trees. The path in this area narrowed and exhibited damage consistent with weaker wind speed, until points near Daniels Run Road and Robinson Road. At that location, the track became less coherent, consistent with radar imagery showing a surge of outflow, thus suggesting the end of the tornadic phase of the storm. Damage at the beginning of the track was consistent with wind speed of around 90 mph, so the tornado has been rated EF1 on the Enhanced Fujita Scale.

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 severe thunderstorm watch, issued at 18:20 UTC and running to 21:41 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 0.02 chance of a tornado within 25 miles. The outlook in force was issued at 16:40 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.

Washington County (AFJ), 13 km from the path, in the two hours either side.

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

The Pittsburgh radar (KPBZ), 48 km away, was scanning. The volume nearest the touchdown began at 19:22 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 2017 tornado in PennsylvaniaEvery tornado in Pennsylvania since 1950Warnings in force in Pennsylvania nowThe forecast where you are

5 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.