Slow moving front brought severe thunderstorms, including landspouts, and heavy rain to portions of south central Nebraska during the evening of May 2nd. A line of thunderstorms blossomed along a stationary front between 6-8PM CDT from southern Gosper County E to Adams County, then NE to Polk County. Once this activity developed, it remained nearly stationary until around 10PM CDT when an upper level disturbance arrived from the W and began to nudge convection to the E and SE. The primary hazard with the initial convection was landspout tornadoes. A total of four landspout tornadoes were observed: one in Kearney County, two in Hamilton County, and one in Polk County. Landspout tornadoes are often very weak and cause little to no damage. These landspouts generally fall into that category, but two of them did cause at least minor damage. Most notable was the landspout that occurred near Hwy 14 just S of Aurora. Not only was it very photogenic, but it also caused damage to a storage building and downed a power line. Other severe reports were limited to severe wind gust in Furnas County, and a large hail report in Kearney County. By late evening and into the overnight, the main threat turned to flash flooding due to the stationary/nearly-stationary nature of the thunderstorms. The heaviest rainfall amounts ranged from 3 to 6 inches and flash flooding was reported in Kearney, Adams, and Hamilton Counties. Impacts ranged from flooded streets, underpasses, and rural roads, to water in some basements in Aurora. Thunderstorms weakened considerably by midnight and lingering rain showers ended by dawn on the morning of the 3rd.
The landspout tornadoes developed within a zone of favorable juxtaposition of steep low level lapse rates, moderate low level instability, weak deep layer shear, and high ambient surface vorticity associated with the stalled surface boundary. Heavy rainfall was supported by aforementioned extremely slow storm motions, as well as seasonably high deep layer moisture.

Tornado in HAMILTON, NEBRASKA
From 02-MAY-21 18:51:00 to 02-MAY-21 18:52:00 (CST-6)
Location: AURORA
Tornado F-scale: EFU
Property damage: 0.00K
Crop damage: 0.00K
Reported by: NWS Storm Survey

This landspout was rated an unknown EF scale and unknown wind speed because of the lack of observable damage. The location was estimated based on pictures and videos.

Tornado in POLK, NEBRASKA
From 02-MAY-21 19:06:00 to 02-MAY-21 19:10:00 (CST-6)
Location: STROMSBURG
Tornado F-scale: EF0
Property damage: 45.00K
Crop damage: 0.00K
Reported by: NWS Storm Survey

This tornado moved north-northwest across a farmstead just south of Highway 66 and then crossed the highway southwest of Stromsburg. It dissipated a little farther north of the highway. The tornado upset a horse trailer, damaged shingles on a house, and ripped off the overhead doors from a metal building.

Tornado in HAMILTON, NEBRASKA
From 02-MAY-21 18:51:00 to 02-MAY-21 18:56:00 (CST-6)
Location: AURORA
Tornado F-scale: EF0
Property damage: 45.00K
Crop damage: 0.00K
Reported by: NWS Storm Survey

This landspout moved north-northwest for approximately 1 mile before diminishing roughly as it crossed Highway 14 just south of Aurora. The main observable damage was damage to storage building roll-up doors, a couple of larger overhead doors and a downed power line. The treeline near the start of the tornado had evidence of cornstalks lofted up into the trees and power lines.

Thunderstorm Wind in FURNAS, NEBRASKA
From 02-MAY-21 18:32:00 to 02-MAY-21 18:32:00 (CST-6)
Location: CAMBRIDGE
Magnitude: 56.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Storm Chaser

This wind gust was measured with a handheld anemometer.

Hail in KEARNEY, NEBRASKA
From 02-MAY-21 18:45:00 to 02-MAY-21 18:50:00 (CST-6)
Location: MINDEN
Magnitude: 1.75 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Amateur Radio

Flash Flood in HAMILTON, NEBRASKA
From 02-MAY-21 21:00:00 to 03-MAY-21 01:00:00 (CST-6)
Location: MURPHY
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Radar estimated that 4 to 6 inches fell in and around the city of Aurora, with a measurement of 4.23 inches from the Cooperative Observer on the east-southeast side of town. This heavy rain falling in a short amount of time resulted in flash flooding in Aurora. Emergency management reported that some vehicles were flooded out due to high water levels and some homes had water in the basement. There was a report of a vehicle needing assistance due to the underpass being flooded. Rural roads in the area were likely affected as well.

Flash Flood in KEARNEY, NEBRASKA
From 02-MAY-21 21:45:00 to 03-MAY-21 02:15:00 (CST-6)
Location: HEARTWELL
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: County Official

Radar estimated that in general a corridor of 3 to 4 inches fell from northwestern Adams County into central portions of Kearney County, with isolated higher amounts. Measured totals included 4.40 inches from a CoCoRaHS observer located 2 miles northeast of Minden and 3.80 inches from the Cooperative Observer in Minden. A number of county roads were covered, including Primrose Avenue near Highway 6 southeast of Kenesaw, where at least one car left the roadway into the ditch. In Minden, the underpass was blocked off around 11 PM due to flooding, remaining that way through at least 3 AM.

Flash Flood in ADAMS, NEBRASKA
From 02-MAY-21 21:45:00 to 03-MAY-21 02:15:00 (CST-6)
Location: KENESAW
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: County Official

Radar estimated that in general a corridor of 3 to 4 inches fell from northwestern Adams County into central portions of Kearney County, with isolated higher amounts. Measured totals included 4.40 inches from a CoCoRaHS observer located 2 miles northeast of Minden and 3.80 inches from the Cooperative Observer in Minden. A number of county roads were covered, including Primrose Avenue near Highway 6 southeast of Kenesaw, where at least one car left the roadway into the ditch. In Minden, the underpass was blocked off around 11 PM due to flooding, remaining that way through at least 3 AM.

Tornado in KEARNEY, NEBRASKA
From 02-MAY-21 18:57:00 to 02-MAY-21 19:01:00 (CST-6)
Location: AXTELL
Tornado F-scale: EF0
Property damage: 0.00K
Crop damage: 0.00K
Reported by: NWS Storm Survey

This landspout appeared to drift west over the course of a few minutes over farmground just south-southeast of the ethanol plant east of Axtell. Damage was minimal.