A storm system moving through the central plains allowed for low pressure to develop over the high Plains, and a warm front to lift north into the northern Plains. Thunderstorms developed during the early afternoon along a sharping dry line over central Plains and moved northeast. Moisture and thunderstorms moved into eastern Nebraska and southwest Iowa during the late afternoon hours. As shear increased during the evening isolated severe weather was observed over southeast Nebraska, mainly in the form of strong winds and 1 EF1 tornado. Although isolated severe weather occurred, training thunderstorms resulting in extremely heavy rainfall and flash flooding across many areas of southeast Nebraska.

Hail in SALINE, NEBRASKA
From 06-MAY-15 18:01:00 to 06-MAY-15 18:01:00 (CST-6)
Location: TOBIAS
Magnitude: 0.75 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Hail in LANCASTER, NEBRASKA
From 06-MAY-15 22:15:00 to 06-MAY-15 22:15:00 (CST-6)
Location: CLEARIDGE ARPT
Magnitude: 0.88 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Amateur Radio

Thunderstorm Wind in JEFFERSON, NEBRASKA
From 06-MAY-15 18:48:00 to 06-MAY-15 18:54:00 (CST-6)
Location: REYNOLDS
Magnitude: 50.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Emergency Manager

A survey from the emergency manager indicated an area of damaging winds in southwest Jefferson County. Damage included minor outbuilding damage, power lines downed, and center irrigation pivots overturned. The damage appears to have been caused by rear-flank downdrafts.

Thunderstorm Wind in SALINE, NEBRASKA
From 06-MAY-15 18:18:00 to 06-MAY-15 18:18:00 (CST-6)
Location: WESTERN
Magnitude: 50.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Emergency Manager

The emergency manager relayed a report of a spotter estimated wind gust to 60 mph.

Tornado in GAGE, NEBRASKA
From 06-MAY-15 21:49:00 to 06-MAY-15 21:54:00 (CST-6)
Location: CORTLAND
Tornado F-scale: EF1
Property damage: 0.00K
Crop damage: 0.00K
Reported by: NWS Storm Survey

A damage survey indicated a weak tornado developed near Cortland and traveled to the northeast. Damage in Cortland and surrounding areas of Gage County consisted of large tree branches and some minor shed damage. This tornado then continued into Lancaster County.

Tornado in LANCASTER, NEBRASKA
From 06-MAY-15 21:54:00 to 06-MAY-15 21:59:00 (CST-6)
Location: PRINCETON
Tornado F-scale: EF1
Property damage: 0.00K
Crop damage: 0.00K
Reported by: NWS Storm Survey

This tornado continued from Gage County into Lancaster County. The damage along the path of the tornado was generally minor and consisted of outbuildings, large tree branches, and downed power lines. The tornado appeared to reach its maximum intensity along Princeton Road and between 38th and 54th streets. Here several farmsteads were impacted where roof damage to homes was noted, and high-tension power lines were downed.

Thunderstorm Wind in LANCASTER, NEBRASKA
From 06-MAY-15 22:02:00 to 06-MAY-15 22:09:00 (CST-6)
Location: HICKMAN
Magnitude: 62.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: NWS Storm Survey

An area of wind damage was surveyed and appeared to be caused by straight-lined winds. The damage consisted of some minor outbuilding damage, large tree limbs down, and center irrigation pivots overturned.

Thunderstorm Wind in GAGE, NEBRASKA
From 06-MAY-15 21:33:00 to 06-MAY-15 21:39:00 (CST-6)
Location: HOAG
Magnitude: 55.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: NWS Storm Survey

An area of wind damage was surveyed to the northwest of the city of Beatrice. This damage appeared to be straight-lined in nature and consisted on tree branches from 1 to 3 inches in diameter and minor shed damage.

Flash Flood in JEFFERSON, NEBRASKA
From 06-MAY-15 20:49:00 to 06-MAY-15 20:49:00 (CST-6)
Location: DAYKIN
Flood cause: Heavy Rain
Property damage: 10.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Extremely heavy rainfall of 5 to 10 inches occurred across the northern half of Jefferson County. This led to flash flooding across a large part of the northern half of the county with numerous road closures reported.

Flash Flood in SALINE, NEBRASKA
From 06-MAY-15 23:00:00 to 06-MAY-15 23:00:00 (CST-6)
Location: SHESTAK
Flood cause: Heavy Rain
Property damage: 20.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Rainfall of 6 to 10 inches across the county lead to significant flash flooding. In addition to street flooding in the communities of Wilber, De Witt, and Western, State highways 103 and 41 were also closed due to water over the road. At least one water rescue was performed due to the flooding.

Flash Flood in LANCASTER, NEBRASKA
From 06-MAY-15 20:59:00 to 06-MAY-15 22:29:00 (CST-6)
Location: HUSKERVILLE
Flood cause: Heavy Rain
Property damage: 50.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Rainfall of 3 to 7 inches fell across a large portion of Lancaster County. Numerous reports of flash flooding were received, especially in and around the city of Lincoln. There were a large number of flooded streets as well as a few water recuse that took place.

Flash Flood in LANCASTER, NEBRASKA
From 07-MAY-15 02:01:00 to 07-MAY-15 02:55:00 (CST-6)
Location: WAVERLY
Flood cause: Heavy Rain
Property damage: 50.00K
Crop damage: 0.00K
Reported by: Emergency Manager

The heavy rainfall continued across Lancaster County and allowed for flash flooding to continue well into the night. The flash flooding included along the Beal Slough Creek and continued street flooding.

Flash Flood in JEFFERSON, NEBRASKA
From 07-MAY-15 02:55:00 to 07-MAY-15 02:55:00 (CST-6)
Location: DAYKIN
Flood cause: Heavy Rain
Property damage: 500.00K
Crop damage: 0.00K
Reported by: Emergency Manager

The emergency manager reported that flash flooding continued as heavy rainfall continued during the overnight. The flooding destroyed a bridge along state highway 15 in northern Jefferson County.