Multiple severe thunderstorms produced large hail up to softball size, localized flooding rains and one EF1 tornado between the evening of Wednesday the 2nd and early morning hours of Thursday the 3rd. Although no injuries were reported, this was the most significant of several severe weather episodes within South Central Nebraska between May 1st-4th and was also the most prolonged, with dozens of warnings issued over nearly a 12-hour period between 7 PM and 7 AM CDT. Despite the number of storm reports, this event was rather localized as only six counties within the 24-county area bore the brunt of severe weather. Severe storms focused in two primary zones: one a narrow southwest-to-northeast corridor extending from Buffalo through Nance Counties, and the other a concentrated, east-to-west corridor through mainly Adams, Clay and Fillmore Counties. The lone confirmed tornado, which struck after nightfall along the Thayer-Fillmore County line, was only on the ground for approximately one mile but caused considerable damage to a farmstead northeast of Davenport. Several areas experienced hail to at least golf ball size, but some of the most significant hail damage focused in and near northern portions of Hastings, where two separate rounds of large hail occurred between 10 PM-12 AM CDT. During the first round, stones up to softball size were reported within the city, and during the second round 2-inch diameter stones pounded the National Weather Service office. Rainfall wise, the heaviest measured amounts of 3-4 inches targeted much of Clay and Fillmore Counties, resulting in water running over Highway 6 west of Sutton, along with flooding of numerous county roads.
In both primary zones of severe weather described above, things got underway between 7 PM-9 PM CDT. In the northern corridor between Buffalo and Nance Counties, initially linear multicell storms eventually transitioned into brief, semi-discrete supercells, with hail to around golf ball size reported near Amherst, Fullerton and Genoa. By 10 PM CDT, most of this activity north of Interstate 80 had either weakened or moved out of the area to the northeast. Meanwhile, storms within the southern area first developed as a multicell cluster in Nuckolls and Clay Counties. Around sunset, a slow-moving cyclic supercell evolved from this activity, producing the EF1 tornado near Davenport shortly after 10 PM CDT. Although reports of funnel clouds continued as this supercell drifted northeast toward Strang, no additional tornado touchdowns were confirmed. Between 10 PM-2 AM CDT, a nearly solid east-west corridor of hail and heavy rain-producing severe storms trained near the Highway 6 corridor between Adams and Fillmore Counties, as the original tornadic storm exited Fillmore County to the east. Between 2 AM-4 AM CDT, there was a brief lull in storm severity, while additional activity flared up farther north and west near the Interstate 80 and Highway 6 corridors. Finally, between 4 AM-7 AM CDT, one last round of hail-producing severe storms tracked east across parts of Adams, Clay and Fillmore Counties before exiting into eastern Nebraska.
Regarding synoptic and mesoscale forcing, broad southwesterly flow aloft was not overly strong, with South Central Nebraska positioned well south of the primary shortwave trough traversing the Northern Rockies and Northern Plains. As a result, the initiation of severe storms was largely driven by the combination of strong convective instability and low level convergence. At the surface, the northern zone of severe weather was tied to a southwest-to-northeast oriented front/retreating outflow boundary. The initiation of the southern storm cluster and cyclic tornadic supercell appeared to be triggered by persistent moisture convergence along the northeast periphery of a weak surface low in north central Kansas. Once these storms developed, the onset of a modest low level jet after nightfall helped to enhance low level shear profiles, with 0-1 kilometer storm relative helicity around 200 m2/s2 by the time of the EF1 tornado. The mesoscale environment was quite supportive of supercells, with mid-evening parameters including 40 knots of 0-6 kilometer vertical wind shear and at least 3000 J/kg mixed-layer CAPE.

Hail in HOWARD, NEBRASKA
From 02-MAY-12 18:29:00 to 02-MAY-12 18:29:00 (CST-6)
Location: DANNEBROG
Magnitude: 0.75 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Fire Department/Rescue

Hail in HOWARD, NEBRASKA
From 02-MAY-12 18:47:00 to 02-MAY-12 18:47:00 (CST-6)
Location: ST PAUL
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Hail in NANCE, NEBRASKA
From 02-MAY-12 19:24:00 to 02-MAY-12 19:24:00 (CST-6)
Location: FULLERTON
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Hail in NUCKOLLS, NEBRASKA
From 02-MAY-12 19:34:00 to 02-MAY-12 19:34:00 (CST-6)
Location: ANGUS
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Hail in CLAY, NEBRASKA
From 02-MAY-12 20:28:00 to 02-MAY-12 20:28:00 (CST-6)
Location: EDGAR
Magnitude: 0.88 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Hail in FILLMORE, NEBRASKA
From 02-MAY-12 20:49:00 to 02-MAY-12 20:49:00 (CST-6)
Location: SHICKLEY
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Hail in CLAY, NEBRASKA
From 02-MAY-12 21:05:00 to 02-MAY-12 21:05:00 (CST-6)
Location: CLAY CENTER
Magnitude: 0.75 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: COOP Observer

Hail in ADAMS, NEBRASKA
From 02-MAY-12 21:10:00 to 02-MAY-12 21:13:00 (CST-6)
Location: HASTINGS
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Storm Chaser

Hail in FILLMORE, NEBRASKA
From 02-MAY-12 21:21:00 to 02-MAY-12 21:21:00 (CST-6)
Location: STRANG
Magnitude: 0.75 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Hail in ADAMS, NEBRASKA
From 02-MAY-12 21:27:00 to 02-MAY-12 21:27:00 (CST-6)
Location: HASTINGS
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Broadcast Media

Quarter size hail was reported at the intersection of 12th and Bellevue.

Hail in HAMILTON, NEBRASKA
From 02-MAY-12 21:44:00 to 02-MAY-12 21:44:00 (CST-6)
Location: GILTNER
Magnitude: 0.88 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Fire Department/Rescue

Hail in FILLMORE, NEBRASKA
From 02-MAY-12 21:47:00 to 02-MAY-12 21:47:00 (CST-6)
Location: GENEVA
Magnitude: 0.75 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Hail in ADAMS, NEBRASKA
From 02-MAY-12 22:17:00 to 02-MAY-12 22:17:00 (CST-6)
Location: HASTINGS
Magnitude: 0.75 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Penny size hail reported at the intersection of 12th and Showboat.

Hail in FILLMORE, NEBRASKA
From 02-MAY-12 22:33:00 to 02-MAY-12 22:33:00 (CST-6)
Location: GENEVA
Magnitude: 0.88 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Hail in ADAMS, NEBRASKA
From 02-MAY-12 22:36:00 to 02-MAY-12 22:37:00 (CST-6)
Location: HASTINGS
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Quarter size hail reported near the intersection of 12th Street and Brentwood Avenue.

Hail in ADAMS, NEBRASKA
From 02-MAY-12 23:26:00 to 02-MAY-12 23:26:00 (CST-6)
Location: AYR
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Hail in CLAY, NEBRASKA
From 03-MAY-12 00:08:00 to 03-MAY-12 00:08:00 (CST-6)
Location: DEWEESE
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Hail in CLAY, NEBRASKA
From 03-MAY-12 00:26:00 to 03-MAY-12 00:26:00 (CST-6)
Location: CLAY CENTER
Magnitude: 0.88 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: COOP Observer

Hail in CLAY, NEBRASKA
From 03-MAY-12 00:42:00 to 03-MAY-12 00:42:00 (CST-6)
Location: SUTTON
Magnitude: 0.75 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Hail in CLAY, NEBRASKA
From 03-MAY-12 01:02:00 to 03-MAY-12 01:02:00 (CST-6)
Location: GLENVILLE
Magnitude: 0.88 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Hail in ADAMS, NEBRASKA
From 03-MAY-12 03:44:00 to 03-MAY-12 03:44:00 (CST-6)
Location: HASTINGS
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: NWS Employee

Hail in CLAY, NEBRASKA
From 03-MAY-12 04:51:00 to 03-MAY-12 04:51:00 (CST-6)
Location: CLAY CENTER
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Heavy Rain in FILLMORE, NEBRASKA
From 02-MAY-12 06:00:00 to 03-MAY-12 06:00:00 (CST-6)
Location: GENEVA
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

A rainfall total of 3.55 inches was reported over a 24 hour period by a Nebraska Rainfall Assessment and Information Network Observer.

Heavy Rain in CLAY, NEBRASKA
From 02-MAY-12 06:00:00 to 03-MAY-12 06:00:00 (CST-6)
Location: CLAY CENTER
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

A rainfall total of 3.10 inches was reported over a 24 hour period by a Nebraska Rainfall Assessment and Information Network Observer.

Heavy Rain in FILLMORE, NEBRASKA
From 02-MAY-12 06:00:00 to 03-MAY-12 06:00:00 (CST-6)
Location: FAIRMONT
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Emergency Manager

A rainfall total of 3.45 inches was reported over a 24 hour period.

Heavy Rain in CLAY, NEBRASKA
From 02-MAY-12 07:00:00 to 03-MAY-12 07:00:00 (CST-6)
Location: CLAY CENTER
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

A rainfall total of 3.43 inches was reported over a 24 hour period by a Nebraska Rainfall Assessment and Information Network Observer.

Heavy Rain in FILLMORE, NEBRASKA
From 02-MAY-12 07:00:00 to 03-MAY-12 07:00:00 (CST-6)
Location: FAIRMONT
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

A rainfall total of 3.21 inches was reported over a 24 hour period by a Nebraska Rainfall Assessment and Information Network Observer.

Heavy Rain in FILLMORE, NEBRASKA
From 02-MAY-12 16:00:00 to 03-MAY-12 16:00:00 (CST-6)
Location: GENEVA
Property damage: 0.00K
Crop damage: 0.00K
Reported by: COOP Observer

A 24 hour rainfall total of 3.22 inches was reported.

Hail in NANCE, NEBRASKA
From 02-MAY-12 18:50:00 to 02-MAY-12 18:50:00 (CST-6)
Location: BELGRADE
Magnitude: 1.50 
Property damage: 25.00K
Crop damage: 250.00K
Reported by: Storm Chaser

Hail in NANCE, NEBRASKA
From 02-MAY-12 18:50:00 to 02-MAY-12 18:50:00 (CST-6)
Location: BELGRADE
Magnitude: 1.75 
Property damage: 25.00K
Crop damage: 250.00K
Reported by: Law Enforcement

Hail in NANCE, NEBRASKA
From 02-MAY-12 19:07:00 to 02-MAY-12 19:10:00 (CST-6)
Location: FULLERTON
Magnitude: 1.50 
Property damage: 25.00K
Crop damage: 250.00K
Reported by: Storm Chaser

Hail in CLAY, NEBRASKA
From 02-MAY-12 19:34:00 to 02-MAY-12 19:34:00 (CST-6)
Location: CLAY CENTER
Magnitude: 1.75 
Property damage: 25.00K
Crop damage: 250.00K
Reported by: Law Enforcement

Hail in BUFFALO, NEBRASKA
From 02-MAY-12 19:35:00 to 02-MAY-12 19:50:00 (CST-6)
Location: AMHERST
Magnitude: 1.75 
Property damage: 25.00K
Crop damage: 250.00K
Reported by: Trained Spotter

Hail in NANCE, NEBRASKA
From 02-MAY-12 19:38:00 to 02-MAY-12 19:38:00 (CST-6)
Location: FULLERTON
Magnitude: 2.00 
Property damage: 75.00K
Crop damage: 250.00K
Reported by: Storm Chaser

Hail in NANCE, NEBRASKA
From 02-MAY-12 19:45:00 to 02-MAY-12 19:45:00 (CST-6)
Location: FULLERTON
Magnitude: 1.25 
Property damage: 15.00K
Crop damage: 125.00K
Reported by: Storm Chaser

Hail in NANCE, NEBRASKA
From 02-MAY-12 19:56:00 to 02-MAY-12 19:56:00 (CST-6)
Location: GENOA
Magnitude: 2.00 
Property damage: 75.00K
Crop damage: 250.00K
Reported by: Law Enforcement

Hail in NANCE, NEBRASKA
From 02-MAY-12 20:05:00 to 02-MAY-12 20:05:00 (CST-6)
Location: GENOA
Magnitude: 2.00 
Property damage: 75.00K
Crop damage: 250.00K
Reported by: Storm Chaser

Tornado in FILLMORE, NEBRASKA
From 02-MAY-12 21:06:00 to 02-MAY-12 21:07:00 (CST-6)
Location: SHICKLEY
Tornado F-scale: EF1
Property damage: 100.00K
Crop damage: 0.00K
Reported by: NWS Storm Survey

This tornado crossed from Thayer County into Fillmore County, touching down approximately 2.5 miles northeast of Davenport and lifting approximately 3.5 miles northeast of Davenport. Along its path, a farmstead sustained house, garage and vehicle damage and a grain bin was destroyed.  Two outbuildings, including a recently built barn, were destroyed and a center irrigation pivot was twisted. The maximum wind speed was estimated at 105 mph.

Hail in ADAMS, NEBRASKA
From 02-MAY-12 21:15:00 to 02-MAY-12 21:15:00 (CST-6)
Location: HASTINGS
Magnitude: 1.75 
Property damage: 250.00K
Crop damage: 0.00K
Reported by: Amateur Radio

Golf ball size hail reported at Lake Hastings.

Hail in ADAMS, NEBRASKA
From 02-MAY-12 21:17:00 to 02-MAY-12 21:17:00 (CST-6)
Location: HASTINGS
Magnitude: 4.25 
Property damage: 750.00K
Crop damage: 0.00K
Reported by: Public

Hail to the size of softballs was reported on the north side of town.

Hail in ADAMS, NEBRASKA
From 02-MAY-12 21:30:00 to 02-MAY-12 21:30:00 (CST-6)
Location: HASTINGS
Magnitude: 1.75 
Property damage: 250.00K
Crop damage: 0.00K
Reported by: Broadcast Media

Golf ball size hail was reported at the intersection of 14th and California.

Hail in CLAY, NEBRASKA
From 02-MAY-12 21:34:00 to 02-MAY-12 21:36:00 (CST-6)
Location: CLAY CENTER
Magnitude: 1.25 
Property damage: 20.00K
Crop damage: 400.00K
Reported by: COOP Observer

Hail in ADAMS, NEBRASKA
From 02-MAY-12 22:47:00 to 02-MAY-12 22:47:00 (CST-6)
Location: HASTINGS
Magnitude: 2.50 
Property damage: 1.00M
Crop damage: 250.00K
Reported by: NWS Employee

Hail in ADAMS, NEBRASKA
From 02-MAY-12 22:38:00 to 02-MAY-12 22:38:00 (CST-6)
Location: JUNIATA
Magnitude: 2.00 
Property damage: 1.80M
Crop damage: 250.00K
Reported by: Trained Spotter

Hail in ADAMS, NEBRASKA
From 02-MAY-12 22:44:00 to 02-MAY-12 22:44:00 (CST-6)
Location: HASTINGS
Magnitude: 2.00 
Property damage: 200.00K
Crop damage: 250.00K
Reported by: Official NWS Observations

Hail measured at the NWS office.

Hail in CLAY, NEBRASKA
From 03-MAY-12 00:28:00 to 03-MAY-12 00:28:00 (CST-6)
Location: FAIRFIELD
Magnitude: 1.75 
Property damage: 25.00K
Crop damage: 500.00K
Reported by: Emergency Manager

Hail in ADAMS, NEBRASKA
From 03-MAY-12 03:13:00 to 03-MAY-12 03:13:00 (CST-6)
Location: HOLSTEIN
Magnitude: 1.75 
Property damage: 25.00K
Crop damage: 500.00K
Reported by: Public

Flash Flood in CLAY, NEBRASKA
From 03-MAY-12 00:00:00 to 03-MAY-12 02:00:00 (CST-6)
Location: SARONVILLE
Flood cause: Heavy Rain
Property damage: 25.00K
Crop damage: 1.00M
Reported by: Law Enforcement

Water was reported running over Highway 6 approximately 1.5 miles east of the Highway 14 intersection.  Numerous rural roads were under water.

Tornado in THAYER, NEBRASKA
From 02-MAY-12 21:03:00 to 02-MAY-12 21:06:00 (CST-6)
Location: DAVENPORT
Tornado F-scale: EF1
Property damage: 100.00K
Crop damage: 0.00K
Reported by: NWS Storm Survey

This tornado crossed from Thayer County into Fillmore County, touching down approximately 2.5 miles northeast of Davenport and lifting approximately 3.5 miles northeast of Davenport. Along its path, a farmstead sustained house, garage and vehicle damage and a grain bin was destroyed.  Two outbuildings, including a recently built barn, were destroyed and a center irrigation pivot was twisted. The maximum wind speed was estimated at 105 mph.