Severe thunderstorms developed on May 21st as an upper level low moved across the area and encountered an unstable air mass.  Surface winds were from the southeast which helped to add to low level shear and tornado development. Thunderstorms redeveloped over some of the same areas.  Training of storms led to flash flooding across the region.

Tornado in ADAMS, OHIO
From 21-MAY-10 19:44:00 to 21-MAY-10 19:52:00 (EST-5)
Location: BRADYVILLE
Tornado F-scale: EF1
Property damage: 135.00K
Reported by: NWS Storm Survey

The tornado initially touched down just north and east of the intersection of Old Dutch Road and Gray Road.  The tornado moved north on the east side of Old Dutch Road and heavily damaged several well constructed barns and outbuildings.  Mature, healthy trees were snapped at the trunk along this path.  The tornado crossed Stanfield Road and crossed Old Dutch Road near Clayton Pike.  Along this stretch, the tornado caused significant tree damage, minor damage to homes, and significant damage to numerous barns and outbuildings.  More trees were toppled as the tornado crossed Clayton Pike again, west of Old Dutch Road.  At this point, it appears the tornado began to intermittently lift, with the next reportable damage on neighboring Suck Run Road where a house was found with windows blown out in addition to significant tree damage.  The damage to the barns and trees is consistent with wind speeds around 110 miles per hour.

Tornado in BROWN, OHIO
From 21-MAY-10 17:44:00 to 21-MAY-10 17:45:00 (EST-5)
Location: WHITE OAK
Tornado F-scale: EF1
Property damage: 10.00K
Reported by: NWS Storm Survey

The tornado touched down in the vicinity of Highway 32 and Klein Road in Brown County.  The tornado crossed into Highland County just west of Sicily Road.  The tornado lifted in Highland County near Highway 321, southeast of Buford.  The worst damage occurred to a residence on Sicily Road in Highland County.  A section of roofing was removed from part of the home, the front porch supports were lifted and removed, numerous trees were uprooted near the residence, and a piece of wood was driven into decking material.  Several other barns and outbuildings were destroyed or heavily damaged along the path.  Based on the damage caused by this tornado, wind speeds were estimated at 100 miles per hour.  The tornado was in Brown County from 0544 PM EST until 0545 PM EST.  The tornado continued in Highland County from 0545 PM EST until 0553 PM EST.

Hail in ADAMS, OHIO
From 21-MAY-10 20:57:00 to 21-MAY-10 21:12:00 (EST-5)
Location: WEST UNION
Magnitude: 1.00 
Reported by: Trained Spotter

Flash Flood in ADAMS, OHIO
From 22-MAY-10 00:00:00 to 22-MAY-10 03:00:00 (EST-5)
Location: WEST UNION
Flood cause: Heavy Rain
Property damage: 3.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Flooded roadways were reported throughout the county.

Flash Flood in SCIOTO, OHIO
From 21-MAY-10 22:13:00 to 21-MAY-10 22:45:00 (EST-5)
Location: RARDEN
Flood cause: Heavy Rain
Property damage: 2.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Multiple roads were flooded due to heavy rainfall.

Flash Flood in ADAMS, OHIO
From 21-MAY-10 21:59:00 to 21-MAY-10 22:30:00 (EST-5)
Location: FAIRVIEW
Flood cause: Heavy Rain
Property damage: 85.00K
Crop damage: 0.00K
Reported by: NWS Storm Survey

Three vehicles were washed into a creek.  People were also reported trapped in a mobile home near West Union.  An entire home was shifted and moved off of the foundation from flash flooding along highway 41 near Dunkinsville.  There was also significant debris along creeks in this area.

Tornado in HIGHLAND, OHIO
From 21-MAY-10 17:45:00 to 21-MAY-10 17:53:00 (EST-5)
Location: BUFORD
Tornado F-scale: EF1
Property damage: 100.00K
Reported by: NWS Storm Survey

The tornado touched down in the vicinity of Highway 32 and Klein Road in Brown County.  The tornado crossed into Highland County just west of Sicily Road.  The tornado lifted in Highland County near Highway 321, southeast of Buford.  The worst damage occurred to a residence on Sicily Road in Highland County.  A section of roofing was removed from part of the home, the front porch supports were lifted and removed, numerous trees were uprooted near the residence, and a piece of wood was driven into decking material.  Several other barns and outbuildings were destroyed or heavily damaged along the path.  Based on the damage caused by this tornado, wind speeds were estimated at 100 miles per hour.  The tornado was in Brown County from 0544 PM EST until 0545 PM EST.  The tornado continued in Highland County from 0545 PM EST until 0553 PM EST.

Hail in CLERMONT, OHIO
From 21-MAY-10 17:56:00 to 21-MAY-10 18:01:00 (EST-5)
Location: MILFORD
Magnitude: 0.75 
Reported by: Public

Thunderstorm Wind in WARREN, OHIO
From 21-MAY-10 17:04:00 to 21-MAY-10 17:08:00 (EST-5)
Location: MAINEVILLE
Magnitude: 50.00 EG
Property damage: 1.00K
Reported by: Public

Trees were reported down due to damaging thunderstorm winds.

Thunderstorm Wind in WARREN, OHIO
From 21-MAY-10 17:10:00 to 21-MAY-10 17:14:00 (EST-5)
Location: LEBANON
Magnitude: 50.00 EG
Property damage: 1.00K
Reported by: Public

Large limbs up to 20 inches in diameter were reported down.

Flash Flood in WARREN, OHIO
From 21-MAY-10 18:30:00 to 21-MAY-10 19:30:00 (EST-5)
Location: LEBANON
Flood cause: Heavy Rain
Property damage: 10.00K
Crop damage: 0.00K
Reported by: Public

Water damage was reported at a water park due to heavy rainfall.

Flash Flood in WARREN, OHIO
From 21-MAY-10 18:00:00 to 21-MAY-10 19:30:00 (EST-5)
Location: LEBANON
Flood cause: Heavy Rain
Property damage: 1.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Some roadways were flooded due to heavy rainfall.

Flash Flood in WARREN, OHIO
From 21-MAY-10 17:22:00 to 21-MAY-10 19:30:00 (EST-5)
Location: LEBANON
Flood cause: Heavy Rain
Property damage: 2.00K
Crop damage: 0.00K
Reported by: NWS Employee

Water was rushing over Oregonia road in several locations.  Water was as deep as one foot in some locations.

Flash Flood in HIGHLAND, OHIO
From 21-MAY-10 19:50:00 to 21-MAY-10 20:15:00 (EST-5)
Location: HILLSBORO
Flood cause: Heavy Rain
Property damage: 2.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Flash flooding occurred on many streets and rural roads across the county.

Thunderstorm Wind in ADAMS, OHIO
From 21-MAY-10 20:40:00 to 21-MAY-10 20:44:00 (EST-5)
Location: WEST UNION
Magnitude: 50.00 EG
Property damage: 2.00K
Reported by: Law Enforcement

Numerous trees were reported down due to damaging thunderstorm winds.

Flash Flood in FAYETTE, OHIO
From 21-MAY-10 20:50:00 to 21-MAY-10 23:00:00 (EST-5)
Location: WASHINGTON COURT HOU
Flood cause: Heavy Rain
Property damage: 2.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Several roads in the southern half of the county were flooded due to heavy rainfall.