Between the mid-afternoon and late-evening hours on this Wednesday, separate corridors of severe thunderstorms rolled southward across both eastern and western sections of South Central Nebraska. The first and most widespread round of severe storms focused east of the Highway 281 corridor between 4 PM and 8 PM CDT. These initial storms, highlighted by a mostly outflow-dominant supercell, rapidly intensified across Polk County along the leading edge of a weak east-west line of convection sagging southward from northeast Nebraska. For the next several hours, the initial supercell cluster along with subsequent severe multicell storms developing along its outflow boundary dropped south-southeast through several counties, eventually exiting southern Thayer County around 8 PM CDT. Along the way, there were multiple reports of large hail up to golf ball size and damaging winds up to around 70 MPH. Although no tornadoes were reported, a brief funnel cloud was sighted near the York-Seward County line. One of the most notable areas of wind damage occurred in and near Waco in York County, where several trees and large branches were blown down in town, and three grain bins were destroyed a few miles southeast of town. In eastern Nuckolls County, several minutes of large hail resulted in crop damage along a narrow corridor between Oak and Ruskin. In addition to hail and wind, torrential rainfall of 2.5 to around 4 inches fell in a short time across parts of Polk and York Counties. This resulted in localized flash flooding, with water running over a few roads including Highway 81/92 just west of Osceola.
Around the time the initial corridor of severe storms exited southeast portions of the area, a new east-west line of strong to severe convection flared up well to the northwest, first affecting areas west of Highway 281 and north of Interstate 80. Although this new line of storms eventually dropped southward across the majority of South Central Nebraska, the main focus for severe weather clearly targeted Dawson and Phelps Counties mainly between 9 and 11 PM CDT. Reports from these counties included a roof blown off an outbuilding west of Sumner, and ping pong ball size hail covering Highway 23 between Bertrand and Loomis. In addition, radar-derived products estimated that at least 4 inches of rain might have fallen across northern portions of Dawson County. Although this second round of severe storms weakened around 11 PM CDT, additional non-severe storms continued drifting through portions of South Central Nebraska well into the early morning hours of Thursday the 6th.
The synoptic and mesoscale environment was quite supportive for southward moving clusters of severe storms, thanks to the combination of a very unstable airmass in the presence of favorable west-northwest flow aloft. Around the time of initial afternoon development in the Polk County area, MLCAPE values were quite high, around 4000 J/kg, in the presence of deep-layer vertical wind shear around 40 knots. Despite a lack of pronounced upper forcing, a corridor of weak shortwave energy spread into Nebraska from the north and west, focused along the northern periphery of a broad ridge centered over the southern United States. At the surface, an east-west quasi-stationary front took shape near the Nebraska-Kansas border during the afternoon. Light easterly breezes north of this boundary allowed low level moisture to pool, with surface dewpoints climbing into the low-mid 70s.

Heavy Rain in POLK, NEBRASKA
From 05-JUL-11 15:00:00 to 05-JUL-11 16:45:00 (CST-6)
Location: OSCEOLA
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Between 4 and 5:45 p.m., 4.20 inches of rain fell in Osceola.

Heavy Rain in POLK, NEBRASKA
From 05-JUL-11 15:00:00 to 05-JUL-11 16:45:00 (CST-6)
Location: OSCEOLA
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Between 4 and 5:45 p.m., 4.10 inches of rain fell 5 miles north of Osceola.

Hail in POLK, NEBRASKA
From 05-JUL-11 15:26:00 to 05-JUL-11 15:26:00 (CST-6)
Location: OSCEOLA
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: COOP Observer

Thunderstorm Wind in YORK, NEBRASKA
From 05-JUL-11 15:56:00 to 05-JUL-11 15:56:00 (CST-6)
Location: BENEDICT
Magnitude: 52.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Wind gusts were estimated at 60 MPH.

Hail in FILLMORE, NEBRASKA
From 05-JUL-11 16:53:00 to 05-JUL-11 16:53:00 (CST-6)
Location: EXETER
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Hail in HAMILTON, NEBRASKA
From 05-JUL-11 16:50:00 to 05-JUL-11 17:05:00 (CST-6)
Location: GILTNER
Magnitude: 0.88 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Hail in NUCKOLLS, NEBRASKA
From 05-JUL-11 17:30:00 to 05-JUL-11 18:00:00 (CST-6)
Location: OAK
Magnitude: 1.75 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Golf ball size hail fell for approximately 30 minutes.  Crop damage was reported from Oak to Ruskin along an approximately 4 mile wide path.

Hail in CLAY, NEBRASKA
From 05-JUL-11 18:03:00 to 05-JUL-11 18:03:00 (CST-6)
Location: SUTTON
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Hail in NUCKOLLS, NEBRASKA
From 05-JUL-11 18:30:00 to 05-JUL-11 18:30:00 (CST-6)
Location: OAK
Magnitude: 0.75 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Hail in CLAY, NEBRASKA
From 05-JUL-11 18:31:00 to 05-JUL-11 18:31:00 (CST-6)
Location: CLAY CENTER
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Hail in NUCKOLLS, NEBRASKA
From 05-JUL-11 18:37:00 to 05-JUL-11 18:37:00 (CST-6)
Location: RUSKIN
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Hail in THAYER, NEBRASKA
From 05-JUL-11 19:08:00 to 05-JUL-11 19:09:00 (CST-6)
Location: CHESTER
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Thunderstorm Wind in DAWSON, NEBRASKA
From 05-JUL-11 20:42:00 to 05-JUL-11 20:42:00 (CST-6)
Location: COZAD
Magnitude: 52.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Wind gusts were estimated at 60 MPH.

Thunderstorm Wind in DAWSON, NEBRASKA
From 05-JUL-11 20:58:00 to 05-JUL-11 20:58:00 (CST-6)
Location: OVERTON
Magnitude: 61.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Wind gusts were estimated between 60 and 70 MPH.  Small tree limbs were blown down.

Hail in DAWSON, NEBRASKA
From 05-JUL-11 21:04:00 to 05-JUL-11 21:04:00 (CST-6)
Location: OVERTON
Magnitude: 1.25 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Crop damage was reported in the area.

Hail in DAWSON, NEBRASKA
From 05-JUL-11 21:19:00 to 05-JUL-11 21:19:00 (CST-6)
Location: OVERTON
Magnitude: 1.50 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Hail up to the size of ping pong balls was covering the road just south of the Overton Interstate 80 interchange.

Hail in PHELPS, NEBRASKA
From 05-JUL-11 21:32:00 to 05-JUL-11 21:32:00 (CST-6)
Location: WESTMARK
Magnitude: 1.25 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Thunderstorm Wind in PHELPS, NEBRASKA
From 05-JUL-11 21:44:00 to 05-JUL-11 21:44:00 (CST-6)
Location: LOOMIS
Magnitude: 61.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Wind gusts were estimated between 60 and 70 MPH.

Thunderstorm Wind in FILLMORE, NEBRASKA
From 05-JUL-11 16:53:00 to 05-JUL-11 16:53:00 (CST-6)
Location: EXETER
Magnitude: 52.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Wind gusts were estimated at 60 MPH.

Flash Flood in POLK, NEBRASKA
From 05-JUL-11 16:15:00 to 05-JUL-11 20:15:00 (CST-6)
Location: POLK
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Rainfall amounts of 2 to 4 inches fell over a short period of time across central and southern portions of Polk County, which resulted in water running over Highway 81/92 just west of Osceola as well as a few area rural roads.

Flash Flood in YORK, NEBRASKA
From 05-JUL-11 16:15:00 to 05-JUL-11 20:15:00 (CST-6)
Location: ARBORVILLE
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Rainfall amounts of 1 to 3 inches fell over a short period of time across northern portions of York County, which resulted in water over a few area rural roads.

Heavy Rain in YORK, NEBRASKA
From 05-JUL-11 06:00:00 to 06-JUL-11 06:00:00 (CST-6)
Location: YORK
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Total rainfall of 3.05 inches fell over the past 24 hours.

Heavy Rain in POLK, NEBRASKA
From 05-JUL-11 06:00:00 to 06-JUL-11 06:00:00 (CST-6)
Location: SHELBY
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Total rainfall of 3.46 inches fell over the past 24 hours.

Heavy Rain in POLK, NEBRASKA
From 05-JUL-11 06:00:00 to 06-JUL-11 06:00:00 (CST-6)
Location: OSCEOLA
Property damage: 0.00K
Crop damage: 0.00K
Reported by: COOP Observer

Total rainfall of 3.86 inches fell over the past 24 hours, most falling during the late afternoon hours on the 5th.

Thunderstorm Wind in POLK, NEBRASKA
From 05-JUL-11 15:23:00 to 05-JUL-11 15:23:00 (CST-6)
Location: OSCEOLA
Magnitude: 52.00 EG
Property damage: 20.00K
Crop damage: 0.00K
Reported by: COOP Observer

Wind gusts were estimated at 60 MPH, knocking down a large tree limb which caused roof damage to the garage.

Hail in POLK, NEBRASKA
From 05-JUL-11 15:31:00 to 05-JUL-11 15:35:00 (CST-6)
Location: OSCEOLA
Magnitude: 1.50 
Property damage: 25.00K
Crop damage: 1.00M
Reported by: COOP Observer

Thunderstorm Wind in YORK, NEBRASKA
From 05-JUL-11 16:15:00 to 05-JUL-11 16:15:00 (CST-6)
Location: BENEDICT
Magnitude: 61.00 EG
Property damage: 25.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Wind gusts were estimated between 60 and 70 MPH.  Numerous tree limbs up to 6 inches in diameter were blown down.

Thunderstorm Wind in YORK, NEBRASKA
From 05-JUL-11 16:25:00 to 05-JUL-11 16:27:00 (CST-6)
Location: WACO
Magnitude: 61.00 EG
Property damage: 120.00K
Crop damage: 1.00M
Reported by: Newspaper

Wind gusts were estimated at 60 to 70 MPH.  Numerous tree limbs were blown down in town, some a foot or more in diameter.  Approximately 2.5 miles southeast of town, 3 grain bins were destroyed and an irrigation pivot was overturned.

Hail in HAMILTON, NEBRASKA
From 05-JUL-11 16:47:00 to 05-JUL-11 16:47:00 (CST-6)
Location: HAMPTON
Magnitude: 1.75 
Property damage: 25.00K
Crop damage: 1.00M
Reported by: Emergency Manager

Hail in HAMILTON, NEBRASKA
From 05-JUL-11 17:05:00 to 05-JUL-11 17:05:00 (CST-6)
Location: GILTNER
Magnitude: 1.75 
Property damage: 25.00K
Crop damage: 1.00M
Reported by: Public

Hail in FILLMORE, NEBRASKA
From 05-JUL-11 17:57:00 to 05-JUL-11 17:57:00 (CST-6)
Location: FAIRMONT
Magnitude: 1.75 
Property damage: 25.00K
Crop damage: 1.00M
Reported by: Emergency Manager

Thunderstorm Wind in DAWSON, NEBRASKA
From 05-JUL-11 20:15:00 to 05-JUL-11 20:15:00 (CST-6)
Location: SUMNER
Magnitude: 56.00 EG
Property damage: 25.00K
Crop damage: 1.00M
Reported by: Newspaper

Wind gusts were estimated at 65 MPH, with an outbuilding losing part of its roof.  Crop damage was also reported in the area.

Hail in DAWSON, NEBRASKA
From 05-JUL-11 20:36:00 to 05-JUL-11 20:38:00 (CST-6)
Location: LEXINGTON
Magnitude: 1.75 
Property damage: 25.00K
Crop damage: 1.00M
Reported by: Trained Spotter

Hail in PHELPS, NEBRASKA
From 05-JUL-11 21:30:00 to 05-JUL-11 21:30:00 (CST-6)
Location: BERTRAND
Magnitude: 1.50 
Property damage: 50.00K
Crop damage: 2.00K
Reported by: Storm Chaser

Hail up to the size of ping pong balls was covering Highway 23 between Bertrand and Loomis.