EF1 tornado, Coulson to Sandy Lake, Pennsylvania, September 22, 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

September 22, 2021

Touchdown

6:20 PM EDT (22:20 UTC)

Lifted

6:21 PM EDT (22:21 UTC)

On the ground

1 minutes

Path length

0.3 miles (0.4 km)

Path width

90 yards (82 m)

Deaths

0

Injuries

0

County

Mercer County

Touchdown point

41.362, -80.115

Lift-off point

41.365, -80.112

Record number

2109221620-01

8 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 100 mph.

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

A broken line of thunderstorms was able to develop ahead of an advancing cold front attached to a mature Great Lakes low pressure center. Instability was marginal, but an impressive shear profile lent support to strong and occasionally rotating thunderstorms. A few reports of wind damage were received, and a brief EF1 tornado occurred in Mercer County near Sandy Lake.

Damage was first observed along state route 358 at McCullough's Kitchen Table where a side porch collapsed, a large refrigerator was displaced and flipped over, and large branches were down from a tree. This was determined to be straight line wind damage with an estimated speed of 70 mph. The first signs of tornado damage started just north along Patton Road in Sandy Lake Township. The tornado moved north-north east uprooting softwood and hardwood|trees, where 90 mph wind was estimated. In a corn field on the west side of Patton Road, damage to the crops showed evidence of a tornadic circulation. There was damage to a farm building on Pears Lane along with two large softwood trees that were uprooted and landed on a farm guest house. This damage was caused by straight line wind. The estimated wind speed in this area was around 75 mph.

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 18:23 UTC and running to 22:41 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 0.05 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.

The Pittsburgh radar (KPBZ), 93 km away, was scanning. The volume nearest the touchdown began at 22:17 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

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.