Tornadoes · United States · Ohio · 2009

EF0 tornado, Neptune, Ohio, May 27, 2009

This EF0 tornado ran 0.5 miles across Mercer County on May 27, 2009, touching down at 5:10 PM EDT and reaching 20 yards wide. It killed nobody.

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.

  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.

The record

Rating
EF0
Date
May 27, 2009
Touchdown
5:10 PM EDT (21:10 UTC)
Lifted
5:12 PM EDT (21:12 UTC)
On the ground
2 minutes
Path length
0.5 miles (0.8 km)
Path width
20 yards (18 m)
Deaths
0
Injuries
0
Crop damage
$5,000
County
Mercer County
Touchdown point
40.634, -84.473
Lift-off point
40.638, -84.464
Record number
0905271510-01

What the Weather Service recorded

An isolated supercell developed over northeast Mercer and northwest Auglaize Counties, producing a weak tornado and flash flooding.

A weak tornado briefly touched down in a field just east of Thomas Road, and just west of Mercer-Auglaize County Line Road. The tornado was rated an EF0, with winds around 65 mph.

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

The warnings

28 minutes of warning. NWS ILN issued a tornado warning for this county at 20:42 UTC, 28 minutes before the tornado touched down, in force until 21:15 UTC.

Issued (UTC)ExpiredProductOffice
20:24 UTC21:15 UTCSevere Thunderstorm WarningILN
20:42 UTC21:15 UTCTornado WarningILN
20:44 UTC23:45 UTCFlood AdvisoryILN
21:00 UTC00:00 UTCFlash Flood WarningILN
23:58 UTC04:00 UTCFlood AdvisoryILN

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 General Thunderstorms Risk. The outlook in force was issued at 19:49 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.

Cncnati-Daytn, OH (KILN), 12:00Z

9.2 hours before the tornado, 146 km from the path. May 27, 2009.

Skew-T log-pSkew-T log-p diagram, Cncnati-Daytn, OH at 12:00Z on 2009-05-27Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel lifted from the surface. Mixed-layer CAPE 973 joules per kilogram, CIN -10, lifted condensation level 574 meters above ground. Wind barbs in knots down the right edge.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed. The warm shading is its CAPE, the cool shading the inhibition it has to break through.
HodographHodograph, Cncnati-Daytn, OH at 12:00Z on 2009-05-27The wind through the lowest 10 kilometers as a curve, rings every 10 meters per second labeled in knots. Zero to 1 km storm-relative helicity -85 square meters per square second, 0 to 6 km bulk shear 13 knots.1939Sfc1 km3 km6 km9 kmRMLM
The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km. RM and LM are the right and left moving storms Bunkers' method gives; the shaded area is the 0 to 1 km storm-relative helicity.
Mixed-layer CAPE
973 J/kg
Mixed-layer CIN
-10 J/kg
Surface CAPE
904 J/kg
Mixed-layer LCL
574 m above ground
0-6 km bulk shear
13 kt
0-1 km bulk shear
19 kt
0-1 km storm-relative helicity
-85 m²/s²
0-3 km storm-relative helicity
-70 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0
0-3 km lapse rate
5.3 K/km

Open this sounding in Storm Lab

Cncnati-Daytn, OH (KILN), 00:00Z

2.8 hours after it, 146 km from the path. May 28, 2009.

Skew-T log-pSkew-T log-p diagram, Cncnati-Daytn, OH at 00:00Z on 2009-05-28Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel lifted from the surface. Mixed-layer CAPE 1133 joules per kilogram, CIN -13, lifted condensation level 764 meters above ground. Wind barbs in knots down the right edge.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed. The warm shading is its CAPE, the cool shading the inhibition it has to break through.
HodographHodograph, Cncnati-Daytn, OH at 00:00Z on 2009-05-28The wind through the lowest 10 kilometers as a curve, rings every 10 meters per second labeled in knots. Zero to 1 km storm-relative helicity 49 square meters per square second, 0 to 6 km bulk shear 14 knots.1939Sfc1 km3 km6 km9 kmRMLM
The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km. RM and LM are the right and left moving storms Bunkers' method gives; the shaded area is the 0 to 1 km storm-relative helicity.
Mixed-layer CAPE
1133 J/kg
Mixed-layer CIN
-13 J/kg
Surface CAPE
2509 J/kg
Mixed-layer LCL
764 m above ground
0-6 km bulk shear
14 kt
0-1 km bulk shear
8 kt
0-1 km storm-relative helicity
49 m²/s²
0-3 km storm-relative helicity
72 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0
0-3 km lapse rate
6.5 K/km

Open this sounding in Storm Lab

The radar

The Northern Indiana radar (KIWX), 131 km away, was scanning. The volume nearest the touchdown began at 21:08 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)ReportWhereCountyRemark
20:50 UTCTSTM WND DMG3 Nne MendonMercer, OHLARGE LIMBS DOWNED. VINYL SIDING RIPPED OFF A HOME ALONG STATE ROUTE 117.
20:50 UTCFLASH FLOOD3 Nne MendonMercer, OHWATER RAPIDLY RUSHING DOWN STATE ROUTE 117. DRAINAGE DITCHES OVERFLOWING THEIR BANKS.
20:50 UTCHAIL 13 Nne MendonMercer, OH
21:00 UTCTSTM WND DMG1 N KossuthAuglaize, OHPOWER POLES DOWN NEAR SPENCERVILLE IN THE NORTHERN PORTIONS OF AUGLAIZE COUNTY.
21:00 UTCFLOODSpencervilleAllen, OHWATER FLOWING OVER ROADS AND SOME BASEMENTS FLOODED.
21:10 UTCFLASH FLOOD3 Nne MendonMercer, OHWATER RAPIDLY RUSHING DOWN STATE ROUTE 117. DRAINAGE DITCHES OVERFLOWING THEIR BANKS.
21:10 UTCTORNADO2 Se MendonMercer, OHTORNADO TOUCHED DOWN BRIEFLY IN A FIELD NEAR THE INTERSECTION OF THOMAS ROAD AND MERCER AUGLAIZE COUNTY ROAD.
21:30 UTCTSTM WND DMG1 Wnw SpencervilleAllen, OHPORTION OF ROOF OFF OF HOUSE AS WELL AS A POWER POLE AND LINES DOWN.
21:30 UTCFLOODMonticelloVan Wert, OHROAD CLOSED DUE TO FLOODING AT INTERSECTION OF STATE ROUTE 116 AND 117.
21:30 UTCFLOODSpencervilleAllen, OHNUMEROUS ROADS CLOSED IN THE SPENCERVILLE AREA DUE TO FLOODING.
22:11 UTCFLOODMonticelloVan Wert, OHSOME ROADS FLOODED IN TOWN OF MONTICELLO.
23:34 UTCFLASH FLOOD3 Nne MendonMercer, OHSEVERAL ROADS FLOODED AND CLOSED ACROSS EXTREME NORTHEAST PORTIONS OF THE COUNTY. WATER MOVING ACROSS STATE ROUTE 117.

From the Iowa Environmental Mesonet's archive of National Weather Service local storm reports.

This ground now

The live radar over the trackEvery 2009 tornado in OhioEvery tornado in Ohio since 1950Warnings in force in Ohio nowThe forecast where you are

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.