EF1 tornado, Prompton, Pennsylvania, May 15, 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

May 15, 2018

Touchdown

3:05 PM EDT (19:05 UTC)

Lifted

3:06 PM EDT (19:06 UTC)

On the ground

1 minutes

Path length

0.2 miles (0.4 km)

Path width

25 yards (23 m)

Deaths

0

Injuries

0

Property damage

$50,000

County

Wayne County

Touchdown point

41.590, -75.372

Lift-off point

41.589, -75.368

Record number

1805151305-01

26 damage points were recorded along this path by NWS BGM, in the Damage Assessment Toolkit the survey teams carry. The strongest indicator was rated EF1. The highest wind the damage implies is 108 mph.

• Several large branches were snapped in trees. Trees were likely a mixture of hardwoods and softwoods.
• Thunderstorm winds resulted in the collapse of the wall of a barn just north of Waymart. An adjoining structure was shifted (in totality) several inches on its foundation with no other damage noted.
• Sporadic trees were snapped and uprooted. This type of damage continued to the end of the road. View in picture is looking toward the west.
• Thunderstorm winds resulted in the loss of a signifcant amount of roofing material of a house, especially on its back side. Unable to ascertain quality of construction. A silo across the road also lost its dome.

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

An intense cold front move through central New York and northeast Pennsylvania during the afternoon of the 15th. This front produced a major squall line which eventually evolved into a derecho with estimated wind speeds of up to 115 mph in Wayne County, Pennsylvania. The derecho moved into Sullivan County, New York with winds just shy of 100 mph. Thousands of trees were snapped and uprooted along at least a 35 mile path with many homes damaged from falling trees and high winds.

A weak tornado touched down on the eastern shore of Keen Lake, approximately |120 yards from the coastline. Most of the damage observed with the tornado was |noted near the touchdown point, where several (mostly) pine trees were snapped |and uprooted. Damage to homes in the area was also noted, as well as the loss of |gutters and mesh screening for porches. Minor roof damage was also seen, as |trees were snapped along the path. A weakly convergent path, and sporadic tree |damage, continued along the tornado's path before lifting in an open field just |under one-quarter of a mile east-southeast of its touchdown point.

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 tornado watch, issued at 17:05 UTC and running to 20:23 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 Moderate Risk, with a 0.05 chance of a tornado within 25 miles. The outlook in force was issued at 16:13 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.

Wilkes-Barre/Scranton (AVP), 41 km from the path, in the two hours either side.

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

The Binghamton radar (KBGM), 85 km away, was scanning. The volume nearest the touchdown began at 19:02 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

11 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.