EF1 tornado, Crenshaw to Brockport, Pennsylvania, August 21, 2018

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 21, 2018

Touchdown

4:08 PM EDT (20:08 UTC)

Lifted

4:11 PM EDT (20:11 UTC)

On the ground

3 minutes

Path length

2.4 miles (3.8 km)

Path width

300 yards (274 m)

Deaths

0

Injuries

0

Property damage

$5,000

Counties

Elk and Jefferson counties

Touchdown point

41.234, -78.754

Lift-off point

41.262, -78.727

Record number

1808211408-01

Low pressure tracked northeastward across Michigan and eastern Canada, pushing a warm front across western Pennsylvania in the morning, with some showers and thunderstorms ahead of it. Breaks in the clouds behind this morning activity allowed instability to build once again during the afternoon. The environment behind the warm front was favorable for severe weather with strong wind shear and deep moisture. Several discrete storms were able to form, with rotation and bounded weak echo regions noted in a few storms. However, the only reports of damage were received from Jefferson County. Several reports of trees and wires being blown down were received, and a confirmed EF-1 tornado occurred near Brockway before crossing into Elk County.

An EF-1 tornado touched down in Jefferson County, PA and traveled northeastward into Elk County, PA before lifting near Brockport. The maximum estimated wind speed was estimated at around 90 mph, with a total path length of 2.5 miles (including both Jefferson and Elk County) and a maximum path width of approximately 300 yards.

A ground survey was conducted and found the starting point at |Fermantown Road where three hardwood trees were knocked down. |The storm headed northeast to Coder Road where several homes had |trees fall on them. One house had a large tree limb pierce |through the ceiling. A large tractor was flipped over. This area had |the worst property damage of the entire path. The tornado then crossed|into Elk County.

A NWS storm survey determined that an EF1 tornado touched down in Jefferson County, PA and traveled northeastward into Elk County, PA before lifting near Brockport. Maximum winds were estimated around 90 mph, with maximum path width of approximately 300 yards. The total path length of the tornado was 2.5 miles, with a little over a mile of that occurring in Elk County.

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 18:41 UTC and running to 22:00 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 20:03 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 State College radar (KCCX), 72 km away, was scanning. The volume nearest the touchdown began at 20:07 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 2018 tornado in PennsylvaniaEvery tornado in Pennsylvania since 1950Warnings in force in Pennsylvania nowThe forecast where you are

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.