A very strong and unseasonably cold upper level low pressure system that was tracking across the northern plains brought a strong low level jet to the region during the early morning hours of June 11th.  The warm and unstable air that worked north into the region helped spawn early morning severe thunderstorms across eastern Nebraska and southwest Iowa.  Later that day as the upper level system worked into the central Dakotas, a cold front pushed across the region.  This helped set off another round of thunderstorms that developed over east central Nebraska by late afternoon.
Isolated small supercell thunderstorms developed ahead of the cold front over eastern Nebraska, but they were quickly overtaken by a broken line of larger supercell thunderstorms, some of the heavy precipitation type, that developed along the cold front.  Cell mergers and training were observed well into the evening hours as the activity quickly spread into southwest Iowa.  The storms produced a total of 8 confirmed tornadoes in the Omaha/Valley warning area which covers eastern Nebraska and southwest Iowa.

Thunderstorm Wind in CASS, NEBRASKA
From 11-JUN-08 19:20:00 to 11-JUN-08 19:20:00 (CST-6)
Location: PLATTSMOUTH
Magnitude: 55.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Thunderstorm wind gusts estimated at over 60 mph blew a tree onto a mobile home.  The winds could have been the rear flank downdraft winds from a supercell thunderstorm that produced a tornado a little earlier near Louisville.

Tornado in JEFFERSON, NEBRASKA
From 11-JUN-08 19:38:00 to 11-JUN-08 19:39:00 (CST-6)
Location: JANSEN
Tornado F-scale: EF0
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Emergency Manager

A brief tornado touchdown caused mainly just tree damage 2 miles north of Jansen.

Thunderstorm Wind in SARPY, NEBRASKA
From 11-JUN-08 19:05:00 to 11-JUN-08 19:05:00 (CST-6)
Location: PAPILLION
Magnitude: 58.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

A trained spotter measured thunderstorm wind gusts of 67 mph with home weather equipment.

Hail in BURT, NEBRASKA
From 11-JUN-08 16:20:00 to 11-JUN-08 16:20:00 (CST-6)
Location: LYONS
Magnitude: 0.75 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Hail in SAUNDERS, NEBRASKA
From 11-JUN-08 16:39:00 to 11-JUN-08 16:39:00 (CST-6)
Location: VALPARAISO
Magnitude: 0.75 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Thunderstorm Wind in BURT, NEBRASKA
From 11-JUN-08 17:05:00 to 11-JUN-08 17:05:00 (CST-6)
Location: TEKAMAH
Magnitude: 50.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Thunderstorm wind gusts estimated at 60 mph knocked down large tree limbs and a few trees in the Tekamah area.

Thunderstorm Wind in DOUGLAS, NEBRASKA
From 11-JUN-08 17:15:00 to 11-JUN-08 17:15:00 (CST-6)
Location: RALSTON
Magnitude: 50.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: COOP Observer

Thunderstorm wind gusts estimated at 60 mph downed a tree in the Ralston area.

Hail in CASS, NEBRASKA
From 11-JUN-08 18:48:00 to 11-JUN-08 18:48:00 (CST-6)
Location: GREENWOOD
Magnitude: 1.75 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Near 310th and Church Road.

Tornado in CASS, NEBRASKA
From 11-JUN-08 18:50:00 to 11-JUN-08 19:00:00 (CST-6)
Location: LOUISVILLE
Tornado F-scale: EF1
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

A tornado did intermittent damage from 3 miles southwest of Louisville to 2 miles southwest of Cedar Creek.  Scattered tree damage was reported in this area and some farm outbuildings were destroyed.  A mobile home southwest of Cedar Creek was moved 8 inches off of its foundation.

Hail in LANCASTER, NEBRASKA
From 11-JUN-08 18:12:00 to 11-JUN-08 18:12:00 (CST-6)
Location: WEST LINCOLN
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Hail in SALINE, NEBRASKA
From 11-JUN-08 18:37:00 to 11-JUN-08 18:37:00 (CST-6)
Location: DORCHESTER
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Hail in LANCASTER, NEBRASKA
From 11-JUN-08 18:55:00 to 11-JUN-08 18:55:00 (CST-6)
Location: WEST LINCOLN
Magnitude: 0.75 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

At 66th and Y Streets.

Thunderstorm Wind in DODGE, NEBRASKA
From 11-JUN-08 16:55:00 to 11-JUN-08 16:55:00 (CST-6)
Location: WINSLOW
Magnitude: 50.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Thunderstorm wind gusts estimated at around 60 mph knocked down large tree branches in the Winslow area.

Hail in DOUGLAS, NEBRASKA
From 11-JUN-08 17:39:00 to 11-JUN-08 17:39:00 (CST-6)
Location: VALLEY
Magnitude: 0.75 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: NWS Employee

At the NWS Valley office.

Tornado in DOUGLAS, NEBRASKA
From 11-JUN-08 17:59:00 to 11-JUN-08 18:00:00 (CST-6)
Location: ELK CITY
Tornado F-scale: EF0
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Fire Department/Rescue

A brief tornado caused tree damage around 6 miles north of Elkhorn.

Tornado in CASS, NEBRASKA
From 11-JUN-08 18:39:00 to 11-JUN-08 18:41:00 (CST-6)
Location: GREENWOOD
Tornado F-scale: EF0
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

A brief tornado touchdown caused mainly tree damage on the east edge of Greenwood.

Hail in DOUGLAS, NEBRASKA
From 11-JUN-08 18:00:00 to 11-JUN-08 18:00:00 (CST-6)
Location: OMAHA
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Quarter size hail reported at the intersection of 168th and Bennington.

Hail in SARPY, NEBRASKA
From 11-JUN-08 19:24:00 to 11-JUN-08 19:24:00 (CST-6)
Location: AVERY
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Amateur Radio

Reported along Washington Street.

Hail in SARPY, NEBRASKA
From 11-JUN-08 20:10:00 to 11-JUN-08 20:10:00 (CST-6)
Location: PAPILLION
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: COOP Observer

Hail in DOUGLAS, NEBRASKA
From 11-JUN-08 19:08:00 to 11-JUN-08 19:20:00 (CST-6)
Location: OMAHA
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Hail up to 1 inch in diameter was reported across sections of Omaha including 159th and Giles, 138th and Industrial Road, 108th and Harrison Streets, 120th and W Streets and at 90th and Center.

Hail in SALINE, NEBRASKA
From 11-JUN-08 19:17:00 to 11-JUN-08 19:17:00 (CST-6)
Location: DORCHESTER
Magnitude: 0.88 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Flash Flood in DOUGLAS, NEBRASKA
From 11-JUN-08 18:56:00 to 11-JUN-08 20:30:00 (CST-6)
Location: ELKHORN
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Amateur Radio

Rainfall of 2 to 5 inches fell in a 2 to 3 hour period across sections of Omaha.  The heavy rain produced flash flooding across roads and highways in the metro area which trapped vehicles in high water or forced road closures.  Areas which experienced more significant flooding included West Maple in Elkhorn, Interstate 480 and Martha Street, the I street ramp onto Interstate 80, 12th and Cuming Streets, 48th and Ames Ave., locations near the Creighton campus and near 50th Street and Interstate 80.  Many of these locations had water high enough that vehicles became trapped.  However, there were no reported injuries and any damage was mainly to the vehicles.  There were also numerous other reports of flooded streets in the Omaha area and along sections of Cole Creek and a few branches of the Papillion Creek watershed.

Flash Flood in CASS, NEBRASKA
From 11-JUN-08 21:00:00 to 11-JUN-08 22:00:00 (CST-6)
Location: LOUISVILLE
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Heavy rain produced flash flooding blocking roads near the intersection of 156th and Kiser Streets just south of Louisville.

Flash Flood in SAUNDERS, NEBRASKA
From 11-JUN-08 17:30:00 to 11-JUN-08 19:30:00 (CST-6)
Location: YUTAN
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Amateur Radio

Rainfall of 2 to 3 inches fell in a 2 to 3 hour period across sections of Saunders county.  The heavy rain produced flash flooding across Highway 92 east of Mead and also flooded farmland in the area.

Flash Flood in SARPY, NEBRASKA
From 11-JUN-08 20:20:00 to 11-JUN-08 22:20:00 (CST-6)
Location: GRETNA
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Amateur Radio

Rainfall of around 3 inches in an hour and a half fell across sections of western Sarpy county. The heavy rain produced flash flooding of a couple of subdivisions in the Gretna area with 6 basements flooded.  The flood waters came from a cornfield to the west with debris from the field crossing a road in the subdivision.

Hail in SAUNDERS, NEBRASKA
From 11-JUN-08 17:15:00 to 11-JUN-08 17:25:00 (CST-6)
Location: WESTON
Magnitude: 0.88 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Amateur Radio

Hail that was around nickel size lasted for about 10 minutes.

Hail in DOUGLAS, NEBRASKA
From 11-JUN-08 17:30:00 to 11-JUN-08 17:30:00 (CST-6)
Location: MERCER
Magnitude: 0.88 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Amateur Radio

Near North 312th and Highway 36.

Flood in CASS, NEBRASKA
From 11-JUN-08 23:30:00 to 12-JUN-08 08:15:00 (CST-6)
Location: GREENWOOD
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Official NWS Observations

Areas of heavy rain that fell across the Salt Creek basin during the first week of June, culminated with heavy rain producing thunderstorms on June 11th. This caused Salt Creek to flood around the Greenwood area.  The creek at Greenwood reached 22.5 feet at 245am CDT on June 12th, flood stage is 20 feet.  The flooding affected mainly just agricultural bottom-lands.

Heavy Rain in DOUGLAS, NEBRASKA
From 11-JUN-08 18:30:00 to 11-JUN-08 19:30:00 (CST-6)
Location: SOUTH OMAHA
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Newspaper

Heavy rain caused a roof of a storage building to collapse in east Omaha damaging a truck, trailer and granite supplies.  Rainfall at Eppley from the storm was around 2.25 inches.  The heavy rain also caused flash flooding across the city.

Thunderstorm Wind in SARPY, NEBRASKA
From 11-JUN-08 19:10:00 to 11-JUN-08 19:10:00 (CST-6)
Location: (OFF)OFFUTT AFB
Magnitude: 65.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Thunderstorm wind gusts estimated at over 70 mph downed several large trees and some power lines at a Salvation Army Camp south of Offutt AFB.

Tornado in BURT, NEBRASKA
From 11-JUN-08 17:25:00 to 11-JUN-08 17:27:00 (CST-6)
Location: ARIZONA
Tornado F-scale: EF1
Property damage: 0.00K
Crop damage: 0.00K
Reported by: NWS Storm Survey

The tornado initially touched down in Burt county Nebraska about 4.5 miles west of Little Sioux Iowa.  Center pivot irrigation systems were flipped and trees sustained damage in the area.  Fallen tree limbs damaged homes and blocked roads and some roof damage and broken windows were noted. The storm tracked northeast and crossed the Missouri River and Interstate 29 near mile marker 97, continuing into Harrison county Iowa.  The total path length was around 14 miles and it eventually achieved EF3 strength when it hit a boyscout camp in Monona county Iowa where 4 fatalities and 48 injuries occurred.

Flash Flood in CASS, NEBRASKA
From 11-JUN-08 22:45:00 to 12-JUN-08 00:45:00 (CST-6)
Location: GREENWOOD
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Heavy rain produced flash flooding across Mynard Road between 250th and 262nd Streets and near Highway 63 east of Greenwood.  Roads in these areas were blocked for a while by flood waters.

Flash Flood in LANCASTER, NEBRASKA
From 11-JUN-08 19:30:00 to 11-JUN-08 22:30:00 (CST-6)
Location: ROKEBY
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Newspaper

Heavy rain caused flash flooding across many streets in the Lincoln area.  The Lincoln airport recorded a little over 3 inches of rain on 6/11.  Flooding across streets was reported along Highway 77 northbound lanes, Rosa Parks Way, the 2400 block of North Ninth Street, 20th Street from Cornhusker to Knox, 48th and Cornhusker Highway, the 600 block of Old Cheney, W Street from 14th to 15th Streets was completely flooded, Havelock Ave. from 70th to 80th Streets, and some flooding was also reported along Haines Branch near Pioneers Park.  Other streets were likely flooded.

Thunderstorm Wind in DOUGLAS, NEBRASKA
From 11-JUN-08 18:00:00 to 11-JUN-08 18:00:00 (CST-6)
Location: BENNINGTON
Magnitude: 52.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Thunderstorm winds estimated at 60 mph blew patio chairs into a window causing it to break and also blew a pontoon boat two houses down near Bennington.

Thunderstorm Wind in LANCASTER, NEBRASKA
From 11-JUN-08 18:05:00 to 11-JUN-08 18:05:00 (CST-6)
Location: GARRATT
Magnitude: 50.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Large tree limbs were reported downed on the northwest edge of Lincoln by thunderstorm wind gusts estimated at 60 mph.