Tornadoes · United States · Pennsylvania · 2011
EF1 tornado, Millersburg, Pennsylvania, May 18, 2011
This EF1 tornado ran 0.3 miles across Dauphin County on May 18, 2011, touching down at 6:05 PM EDT and reaching 25 yards wide. It killed nobody, and did $10,000 of property damage.
The rating scale
Tracks are drawn in the color of the rating. The Enhanced Fujita scale rates the damage rather than measuring the wind: the speeds are what that damage is taken to imply.
EF065 to 85 mph
Light damage. Surface peeled off some roofs, gutters and siding damaged, branches broken, shallow-rooted trees pushed over.
EF186 to 110 mphthis tornado
Moderate damage. Roofs badly stripped, mobile homes overturned or badly damaged, exterior doors lost, windows broken.
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.
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.
EF4166 to 200 mph
Devastating damage. Well-built houses leveled, structures with weak foundations moved some distance, cars thrown and large missiles generated.
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.
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.
The record
- Rating
- EF1
- Date
- May 18, 2011
- Touchdown
- 6:05 PM EDT (22:05 UTC)
- Lifted
- 6:06 PM EDT (22:06 UTC)
- On the ground
- 1 minutes
- Path length
- 0.3 miles (0.4 km)
- Path width
- 25 yards (23 m)
- Deaths
- 0
- Injuries
- 0
- Property damage
- $10,000
- County
- Dauphin County
- Touchdown point
- 40.552, -76.933
- Lift-off point
- 40.555, -76.935
- Record number
- 1105181605-01
What the Weather Service recorded
An EF1 tornado was confirmed near Millersburg in Upper Paxton Township Dauphin County.
A survey team from the National Weather Service in State College confirmed a brief EF1 tornado between Millersburg and Killinger in Upper Paxton Township. The tornado touched down on Zimmerman Road and damaged several homes in the area. A portion of the roof to the Queen of Peace Church Rectory was blown off. The tornado moved northwest across PA 25, snapping off and uprooting approximately 15 large trees. Several out buildings were also destroyed. Maximum wind speeds were estimated at 95 mph, placing this tornado on the lower end of the EF1 category. Two residents also reported seeing a funnel cloud.
From NOAA NCEI's Storm Events Database, the narrative the local forecast office wrote for Storm Data.
The warnings
No tornado warning for this county appears in the archive as in force at the moment the tornado touched down.
| Issued (UTC) | Expired | Product | Office |
|---|---|---|---|
| 20:20 UTC | 23:15 UTC | Flood Advisory | CTP |
| 20:31 UTC | 00:25 UTC | Flash Flood Warning | CTP |
| 22:31 UTC | 01:30 UTC | Flash Flood Warning | CTP |
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 forecast that day
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 19:57 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 air that afternoon
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.
Phillips Aaf/Abe, MD (KAPG), 12:00Z
10.1 hours before the tornado, 140 km from the path. May 18, 2011.
- Mixed-layer CAPE
- 79 J/kg
- Mixed-layer CIN
- -31 J/kg
- Surface CAPE
- 482 J/kg
- Mixed-layer LCL
- 561 m above ground
- 0-6 km bulk shear
- 31 kt
- 0-1 km bulk shear
- 16 kt
- 0-1 km storm-relative helicity
- 66 m²/s²
- 0-3 km storm-relative helicity
- 169 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.4
- 0-3 km lapse rate
- 5.8 K/km
The surface observations
Selinsgrove (SEG), 30 km from the path, in the two hours either side.
| Time (UTC) | Temp (°F) | Dew point (°F) | Wind | Gust (kt) | Pressure (mb) | Weather |
|---|---|---|---|---|---|---|
| 20:53 UTC | 68 | 61 | 70° 7 kt | 1010.5 | RA | |
| 21:53 UTC | 67 | 61 | 80° 7 kt | 1010.5 | ||
| 22:53 UTC | 67 | 59 | 130° 11 kt | 1010.8 | ||
| 23:04 UTC | 64.4 | 57.2 | 200° 5 kt | 1011.2 | ||
| 23:53 UTC | 61 | 59 | 210° 3 kt | 1011.5 | -RA BR |
From the Iowa Environmental Mesonet's archive of airport observations.
The radar
The State College radar (KCCX), 99 km away, was scanning. The volume nearest the touchdown began at 22:02 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.
What was reported nearby
Local storm reports within 60 km of the path, in the three hours either side.
| Time (UTC) | Report | Where | County | Remark |
|---|---|---|---|---|
| 22:05 UTC | TORNADO | Millersburg | Dauphin, PA | DAMAGE AREA 25 YARDS WIDE BY A QUARTER MILE LONG START 0605 PM END 0606 PM |
From the Iowa Environmental Mesonet's archive of National Weather Service local storm reports.
This ground now
The live radar over the trackEvery 2011 tornado in PennsylvaniaEvery tornado in Pennsylvania since 1950Warnings in force in Pennsylvania nowThe forecast where you are
The other tornadoes of May 18, 2011
2 more were confirmed in the United States that day.
What this means
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.
Sources
NOAA Storm Prediction Center tornado database, 1950-2025, the official record kept by NOAA's Storm Prediction Center.