Ending a lull of over two weeks without severe thunderstorms, this Saturday afternoon and early evening featured several reports of damaging winds, large hail and gustnadoes, primarily focused within southern and eastern counties of South Central Nebraska such as Webster, Clay, Nuckolls and Fillmore. During the height of the event between 4-7 PM CDT, some of the most significant wind damage occurred in the Hardy and Ruskin areas, where winds estimated to around 75 MPH overturned irrigation pivots, downed power poles and caved in several steel corn seed storage tanks. Also, 66-68 MPH wind gusts were measured near Deweese and at the York airport. Although several gustnadoes were reported in these areas, some of which resembled true tornadoes per storm chaser video, these were typically brief circulations focused along storm outflow and not directly associated with cloud base rotation. As for large hail, there were several reports of 1.5 to 2-inch diameter stones, including nearly 20 minutes of golf ball size hail east of Blue Hill. Very early in the event around 3 PM CDT, an elevated severe storm in far western South Central Nebraska dumped hail up to ping pong ball size northwest of Gothenburg. Rainfall-wise, although the progressive nature of most storms kept amounts under 2 inches, one localized corridor in far northern portions of the 24-county area between Spalding and Greeley tallied 3.28 inches from the cumulative effect of several passing storms.
Breaking down event timing, the first severe storm of the day was the aforementioned elevated post-frontal hail storm that swept across western Dawson County around 3 PM CDT. This ended up being the only storm to reach severe criteria across the western half of South Central Nebraska, as the vast majority of severe weather occurred with surface-based storms erupting near the Highway 281 corridor between 4-5 PM CDT, and eventually exiting the area into eastern Nebraska between 7-8 PM CDT. These storms, which developed along a well-defined surface cold front, started out as three semi-discrete supercells. However, the supercells quickly morphed into a quasi-linear complex due to cell mergers and eastward-surging outflow boundaries in an environment characterized by surface temperature-dewpoint spreads around 20 degrees or greater. Behind the main line of surface based storms, a few severe post-frontal storms flared up near Highway 281 between 6-7 PM CDT, producing nickel to ping pong ball size hail in and just east of Grand Island. The last band of strong storms of the evening departed the Greeley and Nance County area around 9 PM CDT.
On the synoptic scale this was a rather strongly forced severe weather event, as a vigorous shortwave trough migrated from eastern Colorado across southern Nebraska, while at the surface, a sharp north-south oriented cold front reached a position near the Highway 281 corridor by mid-afternoon. Mesoscale severe weather parameters around the time of initial surface-based supercell development included 40-50 knots of 0-6 kilometer vertical wind shear and 1500-2000 J/kg mixed-layer CAPE. Despite several reports of gustnadoes, a more substantial tornado threat was likely mitigated by somewhat meager boundary layer moisture with surface dewpoints only between 55-60F, resulting in higher cloud bases and enhanced outflow.

Hail in WEBSTER, NEBRASKA
From 19-MAY-12 15:30:00 to 19-MAY-12 15:50:00 (CST-6)
Location: BLUE HILL
Magnitude: 1.75 
Property damage: 500.00K
Crop damage: 5.00M
Reported by: Public

Golf ball size hail fell for nearly 20 minutes, causing severe crop damage and building damage in the area.

Hail in CLAY, NEBRASKA
From 19-MAY-12 16:05:00 to 19-MAY-12 16:05:00 (CST-6)
Location: DEWEESE
Magnitude: 2.00 
Property damage: 200.00K
Crop damage: 4.00K
Reported by: Trained Spotter

Hail up to the size of hen eggs resulted in tree damage around the area.

Hail in CLAY, NEBRASKA
From 19-MAY-12 16:16:00 to 19-MAY-12 16:16:00 (CST-6)
Location: DEWEESE
Magnitude: 1.75 
Property damage: 75.00K
Crop damage: 2.00M
Reported by: Trained Spotter

Thunderstorm Wind in CLAY, NEBRASKA
From 19-MAY-12 16:20:00 to 19-MAY-12 16:20:00 (CST-6)
Location: DEWEESE
Magnitude: 61.00 EG
Property damage: 75.00K
Crop damage: 3.00K
Reported by: Public

Wind gusts estimated near 70 mph, combined with an unknown size of hail, resulted in crop damage to at least 3 fields approximately 1 mile west of the Deweese spur off of Highway 14 and 1 mile north of the county line.

Thunderstorm Wind in NUCKOLLS, NEBRASKA
From 19-MAY-12 16:45:00 to 19-MAY-12 16:55:00 (CST-6)
Location: HARDY
Magnitude: 65.00 EG
Property damage: 500.00K
Crop damage: 3.00K
Reported by: Trained Spotter

Wind gusts estimated to be near 75 mph resulted in a swath of damage from Hardy to Ruskin.  At least 4 irrigation pivots were overturned, at least 8 to 10 power poles were damaged or destroyed, and tree limbs as much as 6 to 8 inches in diameter were blown down along this path.  In Hardy, a hybrid seed distribution business suffered damage to seed storage tanks.

Hail in NUCKOLLS, NEBRASKA
From 19-MAY-12 16:50:00 to 19-MAY-12 16:50:00 (CST-6)
Location: SUPERIOR
Magnitude: 1.50 
Property damage: 25.00K
Crop damage: 500.00K
Reported by: Broadcast Media

Thunderstorm Wind in FILLMORE, NEBRASKA
From 19-MAY-12 17:00:00 to 19-MAY-12 17:02:00 (CST-6)
Location: SHICKLEY
Magnitude: 61.00 EG
Property damage: 50.00K
Crop damage: 250.00K
Reported by: Trained Spotter

Wind gusts estimated near 70 mph resulted in an irrigation pivot being overturned and tree limbs of 4 to 5 inches in diameter being knocked down.

Hail in DAWSON, NEBRASKA
From 19-MAY-12 14:11:00 to 19-MAY-12 14:11:00 (CST-6)
Location: GOTHENBURG
Magnitude: 0.88 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Hail in WEBSTER, NEBRASKA
From 19-MAY-12 15:05:00 to 19-MAY-12 15:15:00 (CST-6)
Location: BLUE HILL
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Hail in HAMILTON, NEBRASKA
From 19-MAY-12 16:06:00 to 19-MAY-12 16:06:00 (CST-6)
Location: AURORA
Magnitude: 0.88 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Hail in CLAY, NEBRASKA
From 19-MAY-12 16:12:00 to 19-MAY-12 16:12:00 (CST-6)
Location: FAIRFIELD
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Fire Department/Rescue

Hail in WEBSTER, NEBRASKA
From 19-MAY-12 16:09:00 to 19-MAY-12 16:09:00 (CST-6)
Location: RED CLOUD
Magnitude: 0.88 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Amateur Radio

Hail in NUCKOLLS, NEBRASKA
From 19-MAY-12 16:44:00 to 19-MAY-12 16:44:00 (CST-6)
Location: SUPERIOR
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Hail in CLAY, NEBRASKA
From 19-MAY-12 17:03:00 to 19-MAY-12 17:03:00 (CST-6)
Location: CLAY CENTER
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: COOP Observer

Hail in DAWSON, NEBRASKA
From 19-MAY-12 17:05:00 to 19-MAY-12 17:05:00 (CST-6)
Location: LEXINGTON
Magnitude: 0.75 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Hail in HALL, NEBRASKA
From 19-MAY-12 17:22:00 to 19-MAY-12 17:22:00 (CST-6)
Location: DONIPHAN
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Hail in HALL, NEBRASKA
From 19-MAY-12 17:40:00 to 19-MAY-12 17:40:00 (CST-6)
Location: GRAND IS
Magnitude: 0.75 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Hail in HAMILTON, NEBRASKA
From 19-MAY-12 17:47:00 to 19-MAY-12 17:47:00 (CST-6)
Location: PHILLIPS
Magnitude: 1.50 
Property damage: 25.00K
Crop damage: 500.00K
Reported by: Fire Department/Rescue

Hail in HALL, NEBRASKA
From 19-MAY-12 17:44:00 to 19-MAY-12 17:44:00 (CST-6)
Location: GRAND IS
Magnitude: 0.88 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: NWS Employee

Hail in HALL, NEBRASKA
From 19-MAY-12 17:50:00 to 19-MAY-12 17:50:00 (CST-6)
Location: GRAND IS
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Hail in YORK, NEBRASKA
From 19-MAY-12 16:30:00 to 19-MAY-12 16:30:00 (CST-6)
Location: BRADSHAW
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: COOP Observer

Hail in POLK, NEBRASKA
From 19-MAY-12 16:40:00 to 19-MAY-12 16:40:00 (CST-6)
Location: SHELBY
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Thunderstorm Wind in NUCKOLLS, NEBRASKA
From 19-MAY-12 16:12:00 to 19-MAY-12 16:12:00 (CST-6)
Location: ANGUS
Magnitude: 59.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

A wind gust of 68 mph was measured near the intersection of Highways 14 and 4.

Thunderstorm Wind in YORK, NEBRASKA
From 19-MAY-12 17:15:00 to 19-MAY-12 17:15:00 (CST-6)
Location: YORK ARPT
Magnitude: 57.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: AWOS

Heavy Rain in GREELEY, NEBRASKA
From 19-MAY-12 06:00:00 to 20-MAY-12 06:00:00 (CST-6)
Location: SPALDING
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

A 24 hour rainfall total of 3.28 inches was reported southwest of Spalding by a Nebraska Rainfall Assessment and Information Network Observer.

Hail in DAWSON, NEBRASKA
From 19-MAY-12 14:08:00 to 19-MAY-12 14:08:00 (CST-6)
Location: GOTHENBURG
Magnitude: 1.50 
Property damage: 25.00K
Crop damage: 500.00K
Reported by: Trained Spotter

Hail in WEBSTER, NEBRASKA
From 19-MAY-12 15:20:00 to 19-MAY-12 15:20:00 (CST-6)
Location: BLUE HILL
Magnitude: 1.50 
Property damage: 25.00K
Crop damage: 750.00K
Reported by: Trained Spotter