EF0 tornado, Wentlings Corners, Pennsylvania, May 1, 2017

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

May 1, 2017

Touchdown

3:09 PM EDT (19:09 UTC)

Lifted

3:10 PM EDT (19:10 UTC)

On the ground

1 minutes

Path length

0.9 miles (1.4 km)

Path width

75 yards (69 m)

Deaths

0

Injuries

0

Property damage

$15,000

County

Clarion County

Touchdown point

41.189, -79.553

Lift-off point

41.195, -79.538

Record number

1705011309-01

7 damage points were recorded along this path by NWS PBZ, in the Damage Assessment Toolkit the survey teams carry. The strongest indicator was rated EF1. The highest wind the damage implies is 107 mph.

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

A large low pressure system tracked across the Great Lakes during the late afternoon and early evening, dragging a cold front across the region. Ahead of the front, shortwaves embedded in strong southerly flow supported showers and thunderstorms, some of which became severe during the afternoon. Convection organized into a squall line that produced wind damage. While instability was not excessive, high levels of wind shear and low level helicity produced several rotating storms in the main line. These storms produced 6 confirmed tornadoes including 2 EF-0s across Butler county, and 3 EF-0s and 1 EF-1 in Clarion county in Pennsylvania. Most damage was done to trees or structures from falling/snapped trees.

The National Weather Service in Pittsburgh PA confirmed a tornado near Wentlings Corners in Clarion County PA.||Damage in the Wentlings Corners area appears to have |resulted from a combination of tornadic and non-tornadic wind. A |coherent path was discovered from near Route 338 and Canoe Ripple |Road to an area north of Tippecanoe Road and east of Wentlings |Corners Road.||The damage observed during the survey mainly was to trees, |although residents of the area have provided photographic evidence|of shingle removal from outbuildings and displaced items that are|not part of the set of official damage indicators used during |storm damage surveys. Structural damage that was identified to the|survey team appeared to have resulted indirectly from falling and|flying debris. Photographs provided via social media to the NWS |appear to depict a partial funnel cloud and rain curtains in the |area where damage was sustained.||Additional damage and extreme wind were reported in the area of |Huckleberry Ridge Road/Providence Church Road, but the team could |identify no coherent track in this area. Wind in this area |nevertheless likely reached damaging speed, but the lack of a |coherent track and radar imagery suggest that this wind likely was|associated with a localized surge in outflow to the east of the |tornadic portion of the storm.

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

19 minutes of warning. NWS PBZ issued a tornado warning for this county at 18:50 UTC, 19 minutes before the tornado touched down, in force until 19:15 UTC.

The county was under a tornado watch, issued at 16:32 UTC and running to 20:27 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 Enhanced Risk, with a 0.05 chance of a tornado within 25 miles. The outlook in force was issued at 16:16 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 Pittsburgh radar (KPBZ), 93 km away, was scanning. The volume nearest the touchdown began at 19:07 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

14 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.