Conditions became moderately to highly unstable across eastern Nebraska and southwest Iowa by early afternoon on August 18th ahead of a weak slow moving cold front that was driven southeast by a weak upper level disturbance.  Scattered super-cell thunderstorms developed by early afternoon near the northeast Nebraska and South Dakota border and tracked and developed southeast across eastern Nebraska and southwest Iowa through the afternoon and evening hours for a prolonged severe weather event across the area.  Several of the storms produced very large destructive hail and very strong wind gusts.  At least one tornado was also reported in the area.  As of the second week in September, State Farm Insurance stated it had processed around 1,000 homeowner and 1,400 auto claims in Nebraska from the storm.

Thunderstorm Wind in LANCASTER, NEBRASKA
From 18-AUG-11 19:54:00 to 18-AUG-11 20:03:00 (CST-6)
Location: (LNK)LINCOLN ARPT
Magnitude: 52.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: ASOS

A thunderstorm wind gust was measured at 60 mph by the Asos at the Lincoln airport.  The winds were from the first of 2 super-cell thunderstorms that tracked across the city on the 18th.  The winds downed several trees which in turn caused damage to several homes in the city.  A fallen tree limb shattered the windshield of a fire truck responding to downed wires narrowly missing the passenger and causing 2 injuries due to flying glass.

Thunderstorm Wind in BOONE, NEBRASKA
From 18-AUG-11 18:25:00 to 18-AUG-11 18:25:00 (CST-6)
Location: PETERSBURG
Magnitude: 50.00 EG
Property damage: 1.00K
Crop damage: 0.00K
Reported by: Newspaper

Thunderstorm wind gusts estimated at around 60 mph broke a large tree which crushed a small metal garage when it fell east of Petersburg.

Hail in KNOX, NEBRASKA
From 18-AUG-11 11:38:00 to 18-AUG-11 11:38:00 (CST-6)
Location: NIOBRARA
Magnitude: 0.88 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Hail in KNOX, NEBRASKA
From 18-AUG-11 17:20:00 to 18-AUG-11 17:20:00 (CST-6)
Location: VENUS
Magnitude: 1.75 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: COOP Observer

Hail in DODGE, NEBRASKA
From 18-AUG-11 14:50:00 to 18-AUG-11 14:50:00 (CST-6)
Location: UEHLING
Magnitude: 1.75 
Property damage: 0.00K
Reported by: Newspaper

Hail up to around golf ball-size was accompanied by winds at least at 50 mph and caused areas of crop damage east of Uehling.

Hail in BURT, NEBRASKA
From 18-AUG-11 14:55:00 to 18-AUG-11 14:55:00 (CST-6)
Location: CRAIG
Magnitude: 1.75 
Reported by: Newspaper

Hail at least up to golf ball-size caused extensive crop damage several miles south of Craig as it was accompanied by winds at least 50 mph.

Thunderstorm Wind in BURT, NEBRASKA
From 18-AUG-11 17:55:00 to 18-AUG-11 17:55:00 (CST-6)
Location: LYONS
Magnitude: 50.00 EG
Reported by: Newspaper

Thunderstorm wind gusts estimated at around 60 mph downed tree limbs, a few trees and power lines in the Lyons area.

Hail in ANTELOPE, NEBRASKA
From 18-AUG-11 17:45:00 to 18-AUG-11 18:00:00 (CST-6)
Location: OAKDALE
Magnitude: 1.00 
Reported by: Trained Spotter

Hail up to quarter-size lasted for about 15 minutes in the Oakdale area.

Thunderstorm Wind in BURT, NEBRASKA
From 18-AUG-11 17:44:00 to 18-AUG-11 17:44:00 (CST-6)
Location: TEKAMAH
Magnitude: 51.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: ASOS

The Asos at the Tekamah airport measured a thunderstorm wind gust of 59 mph.

Hail in SAUNDERS, NEBRASKA
From 18-AUG-11 18:22:00 to 18-AUG-11 18:22:00 (CST-6)
Location: WAHOO
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Most of the hail was pea-size, but some stones were nickel to quarter-size.

Hail in ANTELOPE, NEBRASKA
From 18-AUG-11 18:23:00 to 18-AUG-11 18:23:00 (CST-6)
Location: TILDEN
Magnitude: 0.88 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Thunderstorm Wind in DOUGLAS, NEBRASKA
From 18-AUG-11 18:28:00 to 18-AUG-11 19:00:00 (CST-6)
Location: BOYS TOWN
Magnitude: 80.00 MG
Reported by: Trained Spotter

Thunderstorm wind gusts reached 60 to 80+ mph across northern and northeast sections of Omaha from the second super-cell thunderstorm that tracked across the city on the 18th.  The strongest winds were reported at 163rd and Fort Streets, Interstate 80 and the Irvington exit, near 52nd and Maple Streets and around Omaha Eppley Airfield. Trees were downed from Gallagher Park, near 52nd and Maple, toward Eppley.  The wind equipment at the Asos at Eppley was damaged by the wind driven hail from the first storm, but reportedly wind shear measuring equipment around the runways measured gusts of 80 knots.

Thunderstorm Wind in SARPY, NEBRASKA
From 18-AUG-11 18:40:00 to 18-AUG-11 18:40:00 (CST-6)
Location: AVERY
Magnitude: 52.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Thunderstorm wind gusts were estimated at to have reached at least 60 mph by spotters in the Bellevue area.

Thunderstorm Wind in CASS, NEBRASKA
From 18-AUG-11 18:49:00 to 18-AUG-11 18:49:00 (CST-6)
Location: PLATTSMOUTH MUNI ARP
Magnitude: 52.00 EG
Reported by: Law Enforcement

Thunderstorm wind gusts estimated at around 60 mph blew some cars onto road shoulders a few miles south of Plattsmouth.

Hail in DOUGLAS, NEBRASKA
From 18-AUG-11 16:10:00 to 18-AUG-11 16:30:00 (CST-6)
Location: OMAHA
Magnitude: 4.25 
Reported by: Trained Spotter

Hail up to softball-size fell across sections of northern and eastern Omaha from the first of 2 super-cell thunderstorms that tracked across the city on the 18th.  The largest hail fell across the Florence area, where hailstones reached 3 inches in diameter, toward Eppley Airfield where some softball size stones fell.  The hail was accompanied by thunderstorm wind gusts that were measured at 62 mph by Asos at Eppley.  The wind driven hail caused substantial damage to vehicles and houses in eastern and northern Omaha and many cars that were parked in outdoor long-term parking at Eppley had their windows broken out by the first storm then soaked by heavy rain from the second.  Also at Eppley several commercial planes sustained hail damage and a pilot was seriously injured around his eye when a softball-size stone crashed through the passenger gate/ramp leading to a plane at the gate.  Around 270 of 600 decorative globe light along a drive toward the airport were shattered by the hail and wind, resulting in damage of around $500,000.  Hail size was smaller and possibly even absent across the western and southwestern parts of town.   According to State Farm, the largest auto insurer in Nebraska, 1,600 claims were made within a few days of the storm with more likely to follow, with most claims from the Omaha area.

Hail in MADISON, NEBRASKA
From 18-AUG-11 18:52:00 to 18-AUG-11 18:52:00 (CST-6)
Location: NEWMAN GROVE
Magnitude: 1.50 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Hail in KNOX, NEBRASKA
From 18-AUG-11 11:45:00 to 18-AUG-11 11:45:00 (CST-6)
Location: NIOBRARA
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Lots of quarter-size hail was reported by a trained spotter in the Niobrara area.

Flash Flood in DOUGLAS, NEBRASKA
From 18-AUG-11 19:00:00 to 18-AUG-11 22:00:00 (CST-6)
Location: ALBRIGHT
Flood cause: Heavy Rain
Property damage: 5.00K
Crop damage: 0.00K
Reported by: Broadcast Media

Heavy rainfall from the second super-cell thunderstorm that tracked across the city caused flash flooding of several streets in eastern Omaha.  Most of the flooding was in the northeast part of downtown Omaha, but flooding was also reported across the I80 and I480 junction.  In addition, a parking garage at Eppley was flooded.

Thunderstorm Wind in ANTELOPE, NEBRASKA
From 18-AUG-11 17:00:00 to 18-AUG-11 17:00:00 (CST-6)
Location: CLEARWATER
Magnitude: 55.00 EG
Reported by: Newspaper

Thunderstorm wind gusts estimated at over 60 mph uprooted at least one tree in the Clearwater area and also damaged crops and some structures in the area.  The winds could have been from the same super cell thunderstorm that produced a tornado west of town. The wind was accompanied by a lot of hail, most of it small but some up to quarter-size.

Hail in ANTELOPE, NEBRASKA
From 18-AUG-11 17:00:00 to 18-AUG-11 17:00:00 (CST-6)
Location: CLEARWATER
Magnitude: 1.00 
Reported by: Newspaper

Hail, some estimated around quarter-size, was accompanied by thunderstorm wind gusts estimated at over 60 mph.  Enough hail fell that it lasted on the ground well into the evening hours.  The hail and wind caused some vehicle and structure damage in the area.

Hail in KNOX, NEBRASKA
From 18-AUG-11 12:07:00 to 18-AUG-11 12:13:00 (CST-6)
Location: BLOOMFIELD
Magnitude: 4.25 
Reported by: Public

Hail up to softball-size was reported several miles northeast of Bloomfield.  The hail caused crop damage and also some vehicle, home and farm equipment damage in the area.

Thunderstorm Wind in KNOX, NEBRASKA
From 18-AUG-11 12:13:00 to 18-AUG-11 12:13:00 (CST-6)
Location: BLOOMFIELD
Magnitude: 52.00 EG
Reported by: Fire Department/Rescue

Thunderstorm winds reached around 60 mph in the Bloomfield area.  Hail up to softball-size was reported just northeast of the region.

Hail in CEDAR, NEBRASKA
From 18-AUG-11 14:30:00 to 18-AUG-11 14:30:00 (CST-6)
Location: ST HELENA
Magnitude: 1.75 
Reported by: Public

The hail was accompanied by thunderstorm winds estimated at around 60 mph.

Thunderstorm Wind in CASS, NEBRASKA
From 18-AUG-11 19:00:00 to 18-AUG-11 19:03:00 (CST-6)
Location: GREENWOOD
Magnitude: 65.00 EG
Reported by: Fire Department/Rescue

Thunderstorm wind gusts estimated at over 70 mph caused some tree damage in the Greenwood area.  The wind was accompanied by hail up to golf ball-size.

Thunderstorm Wind in PLATTE, NEBRASKA
From 18-AUG-11 19:10:00 to 18-AUG-11 19:10:00 (CST-6)
Location: OCONEE
Magnitude: 52.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Emergency Manager

The Platte county Emergency Manager estimated thunderstorm wind gusts reached around 60 mph several miles northwest of Columbus.

Hail in CASS, NEBRASKA
From 18-AUG-11 19:05:00 to 18-AUG-11 19:05:00 (CST-6)
Location: GREENWOOD
Magnitude: 1.75 
Reported by: Fire Department/Rescue

Golf ball-size hail was accompanied by wind gusts estimated at over 70 mph.

Hail in ANTELOPE, NEBRASKA
From 18-AUG-11 18:10:00 to 18-AUG-11 18:10:00 (CST-6)
Location: ELGIN
Magnitude: 1.00 
Reported by: Newspaper

Hail up to quarter-size was accompanied by winds at least 50 mph in the Elgin area.  The wind and hail caused crop damage in the area.

Hail in CEDAR, NEBRASKA
From 18-AUG-11 14:58:00 to 18-AUG-11 14:58:00 (CST-6)
Location: OBERT
Magnitude: 1.75 
Reported by: Public

The hail was accompanied by winds estimated at 60 mph which broke all the window on the west side of a house in the area.

Hail in PIERCE, NEBRASKA
From 18-AUG-11 15:25:00 to 18-AUG-11 15:25:00 (CST-6)
Location: MC LEAN
Magnitude: 1.50 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Hail in WASHINGTON, NEBRASKA
From 18-AUG-11 15:31:00 to 18-AUG-11 15:31:00 (CST-6)
Location: SPIKER
Magnitude: 2.50 
Reported by: Public

Hail up to tennis ball-size fell around the Herman area.

Hail in CASS, NEBRASKA
From 18-AUG-11 19:11:00 to 18-AUG-11 19:11:00 (CST-6)
Location: ALVO
Magnitude: 1.75 
Reported by: Law Enforcement

Hail in CASS, NEBRASKA
From 18-AUG-11 19:20:00 to 18-AUG-11 19:20:00 (CST-6)
Location: ELMWOOD
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Hail in WASHINGTON, NEBRASKA
From 18-AUG-11 15:51:00 to 18-AUG-11 15:51:00 (CST-6)
Location: BLAIR
Magnitude: 2.50 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Hail between golf ball and tea cup-size fell along with thunderstorm wind gusts estimated at close to 60 mph.

Hail in WASHINGTON, NEBRASKA
From 18-AUG-11 16:01:00 to 18-AUG-11 16:01:00 (CST-6)
Location: FT CALHOUN
Magnitude: 2.50 
Reported by: Trained Spotter

The hail was accompanied by thunderstorm wind gusts estimated at 70 mph and caused extensive crop damage between Blair and Ft. Calhoun.

Thunderstorm Wind in WASHINGTON, NEBRASKA
From 18-AUG-11 16:01:00 to 18-AUG-11 16:01:00 (CST-6)
Location: FT CALHOUN
Magnitude: 61.00 EG
Reported by: Trained Spotter

Thunderstorm wind gusts estimated at 70 mph accompanied hail around tennis ball-size.  The wind and hail caused extensive crop damage between Blair and Ft. Calhoun.

Thunderstorm Wind in NEMAHA, NEBRASKA
From 18-AUG-11 20:30:00 to 18-AUG-11 20:30:00 (CST-6)
Location: AUBURN
Magnitude: 55.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Thunderstorm wind gusts estimated at over 60 mph downed at least 1 tree in the Auburn area.

Hail in SEWARD, NEBRASKA
From 18-AUG-11 20:31:00 to 18-AUG-11 20:31:00 (CST-6)
Location: UTICA
Magnitude: 1.75 
Reported by: Trained Spotter

Hail up to golf ball-size was reported a few miles southeast of Utica.

Hail in SEWARD, NEBRASKA
From 18-AUG-11 20:34:00 to 18-AUG-11 20:34:00 (CST-6)
Location: MILFORD
Magnitude: 1.50 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Thunderstorm Wind in CEDAR, NEBRASKA
From 18-AUG-11 14:30:00 to 18-AUG-11 14:30:00 (CST-6)
Location: ST HELENA
Magnitude: 52.00 EG
Reported by: Public

Thunderstorm winds which were estimated at 60 mph were accompanied by hail up to golf ball-size.

Thunderstorm Wind in CEDAR, NEBRASKA
From 18-AUG-11 14:58:00 to 18-AUG-11 14:58:00 (CST-6)
Location: OBERT
Magnitude: 52.00 EG
Reported by: Public

Thunderstorm winds estimated at 60 mph were accompanied by hail up to golf ball-size.  The wind and hail broke all the west facing windows out of at least 1 house in the area.

Thunderstorm Wind in DOUGLAS, NEBRASKA
From 18-AUG-11 16:22:00 to 18-AUG-11 16:22:00 (CST-6)
Location: OMAHA
Magnitude: 54.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: ASOS

The winds were accompanied by hail that reached at least baseball-size in the area.

Hail in SEWARD, NEBRASKA
From 18-AUG-11 20:32:00 to 18-AUG-11 20:36:00 (CST-6)
Location: GOEHNER
Magnitude: 1.75 
Reported by: Public

Hail up to golf ball-size fell for several minutes in the Goehner area.

Hail in LANCASTER, NEBRASKA
From 18-AUG-11 20:40:00 to 18-AUG-11 20:40:00 (CST-6)
Location: WEST LINCOLN
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Nickel to quarter-size hail was reported across the northwest part of Lincoln and was from the second super-cell thunderstorm that tracked across the city within an hours time.

Hail in LANCASTER, NEBRASKA
From 18-AUG-11 20:44:00 to 18-AUG-11 20:44:00 (CST-6)
Location: EMERALD
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Hail in SALINE, NEBRASKA
From 18-AUG-11 20:49:00 to 18-AUG-11 20:52:00 (CST-6)
Location: DORCHESTER
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Hail up to quarter-size fell for several minutes in the Dorchester area.

Thunderstorm Wind in RICHARDSON, NEBRASKA
From 18-AUG-11 20:58:00 to 18-AUG-11 20:58:00 (CST-6)
Location: FALLS CITY
Magnitude: 52.00 EG
Reported by: Public

Two trees and some large tree limbs were blown down in the Falls City area from thunderstorm wind gusts estimated at around 60 mph.

Hail in SALINE, NEBRASKA
From 18-AUG-11 21:08:00 to 18-AUG-11 21:12:00 (CST-6)
Location: WILBER
Magnitude: 1.50 
Reported by: Emergency Manager

Hail up to 1.5 inches in diameter fell around and just southeast of Wilber.

Hail in CEDAR, NEBRASKA
From 18-AUG-11 16:43:00 to 18-AUG-11 16:43:00 (CST-6)
Location: ST HELENA
Magnitude: 2.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Flood in THURSTON, NEBRASKA
From 18-AUG-11 16:40:00 to 18-AUG-11 16:40:00 (CST-6)
Location: WINNEBAGO
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Heavy rainfall of several inches in an hour or so produced some flooding across Highway 77 from around Winnebago to Walthill.

Hail in MADISON, NEBRASKA
From 18-AUG-11 22:14:00 to 18-AUG-11 22:14:00 (CST-6)
Location: BATTLE CREEK
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Mostly smaller, but there was a lot of it according the law enforcement in the area.

Tornado in ANTELOPE, NEBRASKA
From 18-AUG-11 16:46:00 to 18-AUG-11 16:50:00 (CST-6)
Location: CLEARWATER
Tornado F-scale: EF0
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

A tornado was on ground for about 1 mile west of Clearwater.  The tornado was caught on film by several people, and apparently did little damage.