During the evening and nighttime hours of May 11th, an area of low pressure located over southern Wisconsin slowly progressed northeast over the upper Great Lakes. A frontal boundary extended southeast of the low, across portions of Indiana into southern Ohio. That frontal boundary lifted north during the day on May 12 and stalled directly over northern Ohio. Thunderstorms developed along this boundary and produced large hail and significant rainfall throughout the day on May 12th. The severe thunderstorms and flash flooding continued through May 13th.

Hail in CUYAHOGA, OHIO
From 12-MAY-11 16:00:00 to 12-MAY-11 16:01:00 (EST-5)
Location: CLEVELAND
Magnitude: 1.00 
Property damage: 10.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Thunderstorms produced a swath of pea to quarter sized hail.

Hail in ASHLAND, OHIO
From 12-MAY-11 14:50:00 to 12-MAY-11 15:05:00 (EST-5)
Location: ASHLAND
Magnitude: 1.00 
Property damage: 15.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Thunderstorms produced a swath of penny to quarter sized hail.

Hail in ASHLAND, OHIO
From 12-MAY-11 14:57:00 to 12-MAY-11 15:05:00 (EST-5)
Location: ASHLAND
Magnitude: 1.00 
Property damage: 10.00K
Crop damage: 0.00K
Reported by: Post Office

Thunderstorms produced quarter sized hail.

Hail in ASHLAND, OHIO
From 12-MAY-11 05:15:00 to 12-MAY-11 05:15:00 (EST-5)
Location: JEROMESVILLE
Magnitude: 1.00 
Property damage: 10.00K
Crop damage: 0.00K
Reported by: Fire Department/Rescue

Thunderstorms produced pea to quarter sized hail. Small tree limbs were also downed with these thunderstorms.

Hail in TRUMBULL, OHIO
From 12-MAY-11 14:59:00 to 12-MAY-11 14:59:00 (EST-5)
Location: NEWTON FALLS
Magnitude: 0.88 
Property damage: 1.00K
Crop damage: 0.00K
Reported by: Public

Thunderstorms produced penny to nickel sized hail.

Hail in TRUMBULL, OHIO
From 12-MAY-11 15:15:00 to 12-MAY-11 15:36:00 (EST-5)
Location: WARREN
Magnitude: 1.00 
Property damage: 10.00K
Crop damage: 0.00K
Reported by: Storm Chaser

Thunderstorms produced a swath of pea to quarter sized hail.

Hail in HURON, OHIO
From 12-MAY-11 15:20:00 to 12-MAY-11 15:20:00 (EST-5)
Location: NORWALK
Magnitude: 0.88 
Property damage: 1.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Thunderstorms produced penny to nickel sized hail.

Hail in ASHLAND, OHIO
From 12-MAY-11 04:15:00 to 12-MAY-11 04:15:00 (EST-5)
Location: ASHLAND
Magnitude: 1.25 
Property damage: 20.00K
Crop damage: 0.00K
Reported by: Public

Half dollar sized hail was reported during this thunderstorm. Several vehicles were damaged by hail.

Hail in ERIE, OHIO
From 12-MAY-11 15:30:00 to 12-MAY-11 15:30:00 (EST-5)
Location: AVERY
Magnitude: 1.00 
Property damage: 5.00K
Crop damage: 0.00K
Reported by: Department of Highways

Thunderstorms produced quarter size hail and winds of 60mph to 70mph.

Hail in ERIE, OHIO
From 12-MAY-11 14:16:00 to 12-MAY-11 14:18:00 (EST-5)
Location: HURON
Magnitude: 0.75 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Thunderstorms produced plain M&M to penny sized hail.

Thunderstorm Wind in MAHONING, OHIO
From 12-MAY-11 17:05:00 to 12-MAY-11 17:05:00 (EST-5)
Location: GREENFORD
Magnitude: 50.00 EG
Property damage: 1.00K
Crop damage: 0.00K
Reported by: Public

Thunderstorm winds downed two large trees.

Hail in GEAUGA, OHIO
From 12-MAY-11 14:44:00 to 12-MAY-11 14:51:00 (EST-5)
Location: CHARDON
Magnitude: 1.75 
Property damage: 100.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Thunderstorms produced a swath of quarter to golf ball sized hail. Numerous vehicles were damaged by hail. Homes and crops were also damaged as a result of the large hail.

Hail in GEAUGA, OHIO
From 12-MAY-11 15:35:00 to 12-MAY-11 15:44:00 (EST-5)
Location: CHARDON
Magnitude: 1.75 
Property damage: 100.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Thunderstorms produced a swath of hail ranging in size from penny to half dollar to golf ball. Numerous vehicles and homes were damaged by the large hail. Crops were also damaged as a result of the hail.

Hail in GEAUGA, OHIO
From 13-MAY-11 13:37:00 to 13-MAY-11 13:44:00 (EST-5)
Location: MIDDLEFIELD
Magnitude: 1.75 
Property damage: 100.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Thunderstorms produced quarter to golf ball size hail. Numerous vehicles and homes were damaged by the hail. The large hail also damaged crops in the area.

Hail in MEDINA, OHIO
From 12-MAY-11 16:05:00 to 12-MAY-11 16:05:00 (EST-5)
Location: MEDINA
Magnitude: 1.00 
Property damage: 5.00K
Crop damage: 0.00K
Reported by: Public

Thunderstorms produced quarter sized hail.

Hail in SUMMIT, OHIO
From 12-MAY-11 15:05:00 to 12-MAY-11 15:05:00 (EST-5)
Location: CUYAHOGA FALLS
Magnitude: 1.00 
Property damage: 5.00K
Crop damage: 0.00K
Reported by: Public

Thunderstorms produced nickel to quarter sized hail.

Hail in STARK, OHIO
From 12-MAY-11 17:03:00 to 12-MAY-11 17:03:00 (EST-5)
Location: LOUISVILLE
Magnitude: 0.88 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Thunderstorms produced nickel sized hail.

Thunderstorm Wind in TRUMBULL, OHIO
From 12-MAY-11 16:15:00 to 12-MAY-11 16:15:00 (EST-5)
Location: NEWTON FALLS
Magnitude: 50.00 EG
Property damage: 1.00K
Crop damage: 0.00K
Reported by: Public

Thunderstorm winds downed two large trees.

Hail in TRUMBULL, OHIO
From 12-MAY-11 15:36:00 to 12-MAY-11 15:36:00 (EST-5)
Location: WARREN
Magnitude: 1.00 
Property damage: 5.00K
Crop damage: 0.00K
Reported by: Public

Thunderstorms produced quarter sized hail.

Hail in MARION, OHIO
From 12-MAY-11 20:30:00 to 12-MAY-11 20:30:00 (EST-5)
Location: MARION
Magnitude: 0.25 
Property damage: 1.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Thunderstorms produced dime sized hail.

Hail in PORTAGE, OHIO
From 13-MAY-11 15:15:00 to 13-MAY-11 15:20:00 (EST-5)
Location: RAVENNA
Magnitude: 1.75 
Property damage: 100.00K
Crop damage: 0.00K
Reported by: Public

Thunderstorms produced nickel to golf ball sized hail during this event. Vehicles and homes were damaged by the large hail.

Flood in CUYAHOGA, OHIO
From 12-MAY-11 17:45:00 to 12-MAY-11 19:00:00 (EST-5)
Location: BROADVIEW HGTS
Flood cause: Heavy Rain
Property damage: 5.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Strong thunderstorms with torrential rain brought as much as 2 inches of rain in 1.5 hrs over portions of Cuyahoga County. The runoff from this rainfall cause flooding along Boston Road in Broadview Heights. Other Roads across the county were effected like Brookpark, State Road, and Crocker Road. A minor mudslide occurred along I-480 eastbound near Garfield Heights.

Flood in MEDINA, OHIO
From 12-MAY-11 18:00:00 to 12-MAY-11 19:00:00 (EST-5)
Location: MALLET CREEK
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Torrential rain in severe thunderstorms produced localized flooding over portions of Medina. Numerours roads had water several inches deep with a few isolated road closures. State Rout 42 and 162 were flooded. Doppler Radar estimated as much as 1.75 inches of rain fell within an hour.

Flood in MAHONING, OHIO
From 12-MAY-11 19:00:00 to 12-MAY-11 20:00:00 (EST-5)
Location: CAMPBELL
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Thunderstorms with torrential rainfall moved over Mahoning County during the early evening hours of the 12th. Rainfall rates exceded 1 per hour, with doppler radar estimates of 1 to 2.5 falling over northern Mahoning County. The heaviest rain fell near Youngstown, with basement flooding and some road closures along RT 422 near the Metropark.

Flash Flood in TRUMBULL, OHIO
From 13-MAY-11 16:11:00 to 13-MAY-11 17:00:00 (EST-5)
Location: OAKFIELD
Flood cause: Heavy Rain
Property damage: 20.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Torrential rain with rates over an inch per hour fell over northwest portions of Trumbull County. As much as 2 inches fell within an hour and a half. Several roads were flooded including Route 45. Water levels came up so fast in some local streams and creeks that farm animals had to be rescued in Farmington.

Thunderstorm Wind in MAHONING, OHIO
From 13-MAY-11 13:26:00 to 13-MAY-11 13:26:00 (EST-5)
Location: CANFIELD
Magnitude: 50.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Thunderstorm winds downed a few large tree limbs.

Thunderstorm Wind in SUMMIT, OHIO
From 13-MAY-11 15:50:00 to 13-MAY-11 15:50:00 (EST-5)
Location: CLINTON
Magnitude: 50.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Fire Department/Rescue

Thunderstorm winds downed a large tree and a large tree limb.

Thunderstorm Wind in MEDINA, OHIO
From 12-MAY-11 15:35:00 to 12-MAY-11 15:35:00 (EST-5)
Location: VALLEY CITY
Magnitude: 50.00 EG
Property damage: 40.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Thunderstorm winds snapped several large trees. Several roofs were damaged during this event.

Flash Flood in LAKE, OHIO
From 12-MAY-11 20:18:00 to 12-MAY-11 22:00:00 (EST-5)
Location: MENTOR ON THE LAKE
Flood cause: Heavy Rain
Property damage: 2.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Torrential Rainfall from severe thunderstorms brought upwards of 3 inches of rainfall over portions of Lake County within an hour and a half. In the town of Concord flash flooding was reported. The Big Creek and Gardon Creeks came out of banks, and several roads were flooded. Some homes were threatened by the flood waters along Jason and Christian Ave.

Flash Flood in ASHTABULA, OHIO
From 13-MAY-11 19:45:00 to 13-MAY-11 21:25:00 (EST-5)
Location: NEW LYME
Flood cause: Heavy Rain
Property damage: 30.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Sheriff Department reported a small dam failulre near the town of Orwell. This low head dam released enough water to wash out a road. The dam failure was the result of rapid runoff overwhelming the dam. Rainfall amounts of 2 to 3 inches fell in the area according to Doppler Radar estimates.

Flash Flood in LAKE, OHIO
From 13-MAY-11 18:25:00 to 13-MAY-11 20:30:00 (EST-5)
Location: LANE STATION
Flood cause: Heavy Rain
Property damage: 15.00K
Crop damage: 0.00K
Reported by: Department of Highways

Torrential rain developed along the boundary between the lake breeze and  a stationary front over Lake County. The result was doppler radar estimated rainfall amounts around 2 to 2.5 within an hour and a half. This heavy rainfall resulted in flash flooding over portions of Madison Township. River Road, Ford Road, Madison Road, and Union Streets flooded with over a foot of water. Some depths were over the hoods of cars.

Flash Flood in ASHLAND, OHIO
From 13-MAY-11 23:00:00 to 14-MAY-11 02:00:00 (EST-5)
Location: BAILEY LAKE
Flood cause: Heavy Rain
Property damage: 10.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Strong thunderstorms with torrential rainfall developed over northern Ashland County. Doppler Weather Radar estimated 1 to 2.5 inches of rainfall over a two hour timespan fell during the evening hours. This rainfall resulted in several creeks and streams overspilling their banks. A rescue was conducted near the town of Rowsburg.

Hail in HOLMES, OHIO
From 12-MAY-11 06:55:00 to 12-MAY-11 06:55:00 (EST-5)
Location: FARMERSTOWN
Magnitude: 1.00 
Property damage: 5.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Thunderstorms produced quarter size hail.

Hail in HURON, OHIO
From 12-MAY-11 15:00:00 to 12-MAY-11 15:00:00 (EST-5)
Location: NORWALK
Magnitude: 1.00 
Property damage: 5.00K
Crop damage: 0.00K
Reported by: Public

Thunderstorms produced quarter sized hail.

Flood in TRUMBULL, OHIO
From 12-MAY-11 17:45:00 to 12-MAY-11 20:00:00 (EST-5)
Location: LEAVITTSBURG
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Torrential rainfall from strong thunderstorms brought as much as 1.5-2 to portions of Trumbull County. The rain fell at a high rate of over an inch per hour. This excessive rainfall caused water to runoff into streets as deep at 7-8 in the city of Leavittsburg.