The following events were reported: Flash Flood, Hail, Lightning, Thunderstorm Wind. These occurred near station USW00013874, approximately 32.4568 km away, between 2011-04-15 17:44:00 and 2011-04-16 03:16:00. The events included records with hailstones measuring 28.985294117647058 inches.Thankfully, no injuries or fatalities were reported. The events caused property damage valued at 8842000.0 and crop damage of 0.0. Episode Narrative: A deep, slow moving, negatively tiltled and highly diffluent upper trough was sweeping from the south central into the southeast U.S. during the April 15th and 16th period. A strong Pacific cold front accompanied the upper-level trough. An unseasonably warm, moist and unstable air mass was present across the southeast U.S. in advance of this weather system. An initial line of strong to severe thunderstorms began to move into northwest Georgia during the late afternoon hours of April 15th. As the line progressed further into the state, it evolved more in a large area of showers and thunderstorms with discrete supercells across especially central Georgia. These supercells produced damaging winds, hail, and three tornadoes. As the event continued into the early morning hours of the 16th, the severity decreased, but widespread rain and thunderstorms, along with isolated severe thunderstorms continued until around daybreak. In addition to the severe weather events, the prolonged and heavy rain event resulted in flash flooding along north Atlanta metropolitan area creeks and streams. A deep, slow moving, negatively tiltled and highly diffluent upper trough was sweeping from the south central into the southeast U.S. Event Narrative: The Cobb County Emergency Management Director reported extensive and widespread thunderstorm wind damage across Cobb county from Austell, to Smyrna, to Vinings. The most significant damage was near Austell. In Austell, at least a dozen trees were down affecting five homes. Four of the homes suffered minor to moderate damage, while another suffered minor damage to its roof. The winds also ripped off a portion of the roof of a BJ's Warehouse building near Interstate-20. Wind damage to trees was also observed in the Smyrna area where a spotter measured at least a 52 mph wind gust on personal weather equipment. In Vinings, the public reported that a large sign was ripped off a store at a strip mall on Cobb Parkway with a tree down in the adjacent parking lot. Several power lines were also down between Austell and Vinings, leaving over 1000 people without power. In addition, several roads were blocked from downed trees. Nearly two dozen trees affected roads in eastern Cobb county, including Paces Ferry, Powers Ferry, Kings Ferry, Paper Mill, Cumberland Parkway, Hurt Road, Stillhouse Road, Mabry Road, and Milford Church Road. The Fulton County Emergency Management Director reported that more than 200 trees were down across the central and northern part of the county, but especially around Sandy Springs. A large oak tree fell on a home in Sandy Springs on Riverview Road causing the house to collapse. A couple inside the structure was trapped for several hours without injury until firefighters could remove the tree and rescue them. The home was essentially destroyed. The Douglas County Emergency Management Director reported that several trees were down across the county from Fairplay to northeast of Douglasville. The most significant damage appeared to be on the west and north side of Douglasville. Several trees were down near the intersection of Georgia Highway 5 and Riley Road. A large tree caused a roof to cave in on a structure located in the 6600 block of Bankhead Highway just southwest of Douglasville. The Gwinnett County 911 Center and the public reported that more than a half-a-dozen trees were either down or snapped half-way-up between Snellville and Lawrenceville. The public observed penny-sized hail around Douglasville. WSR-88D radar data suggests that the intensifying thunderstorm across the county likely produced penny-sized hail from northwest of Fairplay in the southwest part of the county to Lithia Springs in the northeast part of the county. An amateur radio operator relayed a report of quarter-sized hail just south of Smyrna. Several reports of penny to quarter-sized hail were received from the public across eastern Cobb county near Marietta. The public reported that hail, some as large as quarters, fell east of Marietta near the Fulton county line for up to 10 minutes. The hail completely covered the ground at several locations. The Cobb County 911 Center reported widespread tree and power line damage across the southeast half of the county. Dozens of trees were down within this area. The damage was most concentrated southeast of Marietta and near Smyrna. Trees were down on cars near the intersection of Interstate-285 and Interstate-75 southeast of Marietta. The Spalding County 911 Center reported that three to four trees were down from the Pike and Lamar county lines northward to the Griffin area. A tree was down on Audubon Circle, Barnesville Road, and Ninth Street. The DeKalb County 911 Center reported that a large tree fell on a home in North Druid Hills causing significant damage to the structure. The Carroll County Emergency Management Director reported penny-sized hail from the northeastern part of the county. The USGS Stream Gage on Sope Creek at Marietta (MARG1) reached its flood stage of 12.0 feet at 11:18 pm on April 15, 2011. The creek remained above flood stage until 3:41 am EDT on April 16, 2011. A vehicle was stranded in flood waters in the eastern part of the county and the basement of a home was flooded on Norman Road in Kennesaw. Otherwise, damage was confined to minor debris removal adjacent to the flooded creek. An amateur radio operator relayed a report of penny-sized hail from the far northern part of the county around Dunwoody. The Douglas County Emergency Management Director reported that a roof on a building in downtown Douglasville collapsed because of strong thunderstorm wind gusts. Another building in Lithia Springs along Bankhead Highway also had a good portion of its roof torn off by strong thunderstorm wind gusts. In addition, widespread damage to trees and power lines was observed throughout the county from just northwest of Fairplay to Lithia Springs. The public observed quarter-sized hail across the east central part of the county near Mount Bethel. The Gwinnett County 911 Center reported that at least two homes in the Norcross area were struck by lightning. One of these, a two-story home, was set on fire and completely destroyed. Amateur radio operators and the public reported hail up to the size of half-dollars and ping-pong balls, possibly some as large as golf balls, across far northwest and north central Gwinnett county from Norcross, to Sugar Hill and Buford. Several reports of penny to quarter-sized hail were also received from this same general area. WSR-88D radar data suggests that the largest hail likely fell near Norcross. The Fulton County 911 Center reported that several trees were down in the Palmetto area. A few shingles were also blown off a roof in North Fulton county in the Alpharetta area, but no other tree or structural damage was noted in that area at this time. The public observed quarter to golf ball-sized hail near and southwest of Sandy Springs in north Fulton county. Hail as large as ping-pong balls was also observed around Roswell. The USGS Stream Gage on Big Creek at Alpharetta (APHG1) reached its flood stage of 7.0 feet at 10:22 pm EDT on April 15, 2011. The creek remained above flood stage at this location until 2:28 pm on April 17, 2011. However, flash flooding was determined to have ended at 422 am on April 17, 2011. Damage was confined to minor debris removal in the vicinity of the flooded creek. Amateur radio operators relayed reports that dozens of trees were down in the east central part of Cobb county near Mount Bethel. Green Forest Parkway was closed at South Cobb Drive and South Atlanta Road.