Multiple thunderstorms formed along and southeast of a line from Red Cloud to York on this Sunday afternoon. However, most of the severe weather was produced by a single supercell. This was the first and most intense storm of the day and it formed over Webster county around 2:30 p.m. CDT. This storm took full advantage of an extremely favorable environment, quickly becoming severe and producing at least one brief, weak tornado just southwest of Glenvil. The storm continued northeast producing several more tornadoes, two of which resulted in a maximum damage rating of EF-3. One of these tornadoes occurred over Clay and Fillmore counties and the other subsequently occurred over Fillmore and Seward counties. The first of these EF-3 tornadoes was on the ground for nearly 22 miles. Damage surveys, photos and video confirmed that this storm produced at least 6 other tornadoes, 3 rated EF-0, 2 rated EF-1 and 1 rated EF-2. One of the EF-1 tornadoes was anticyclonic and touched down just north of Fairmont. To the left of these tornadoes, severe hail was common. The largest hail observed was the size of tennis balls in Glenvil. Large swaths of damaging winds, from the rear flank downdraft, accompanied the tornadoes to their south and southeast. Tornado and wind damage was extensive to trees, power poles, farm buildings including grain bins, and a few homes. Over 200 irrigation pivots were overturned and/or twisted. Multiple farmsteads also endured damage, including the loss of a new  machine shed. By 5:30 p.m., this storm had moved into eastern Nebraska. Other storms developed in its wake, but produced no severe weather.
A very long surface front extended from New England, through the Ohio Valley, across the Central Plains and into the Desert Southwest. Portions of this front were stationary while others were being modulated by several waves of low pressure. The front lifted northward to the Kansas-Nebraska border by daybreak. One low ejected out of Colorado and moved east along the front through northern Kansas during the day. This supercell formed just northeast of this low on the immediate cool side of the front. The upper-level flow featured an amplified western trough and eastern ridge. A closed low was at the base of the trough over the Four Corners region. These storms initiated with the aid of a shortwave trough that ejected into the Central Plains ahead of this low. A strong 100 knot jet streak was at the base of the trough at 300 mb, placing the Central Plains in the favorable left front quadrant. An expansive stratus cloud deck, on the cool side of the front, resulted in a substantial temperature gradient across the front, with afternoon temperatures in the 40s and 50s across much of Nebraska to the mid 80s and low 90s over northern Kansas. This resulted in a tight instability gradient with MLCAPE of 2000 J/kg right along the front. Winds were strong throughout the column. The ejecting low pressure center, combined with the front, resulted in significantly backed winds, enhancing low-level shear. 0-1 km SRH was roughly 300 m2/s2, with 0-3 km SRH 400-600 m2/s2. The environment was very favorable for severe storms and tornadoes.

Hail in ADAMS, NEBRASKA
From 11-MAY-14 03:45:00 to 11-MAY-14 03:45:00 (CST-6)
Location: JUNIATA
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Hail in ADAMS, NEBRASKA
From 11-MAY-14 04:07:00 to 11-MAY-14 04:07:00 (CST-6)
Location: HASTINGS
Magnitude: 0.88 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Hail in ADAMS, NEBRASKA
From 11-MAY-14 04:56:00 to 11-MAY-14 04:56:00 (CST-6)
Location: HASTINGS
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Heavy Rain in HAMILTON, NEBRASKA
From 11-MAY-14 07:00:00 to 12-MAY-14 07:00:00 (CST-6)
Location: STOCKHAM
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

The 24 hour rainfall total reported from Sunday through Monday morning was 4.25 inches.

Heavy Rain in YORK, NEBRASKA
From 10-MAY-14 07:00:00 to 12-MAY-14 07:00:00 (CST-6)
Location: YORK ARPT
Property damage: 0.00K
Crop damage: 0.00K
Reported by: AWOS

The 48 hour rainfall total reported from Saturday through Monday morning was 3.82 inches.

Heavy Rain in YORK, NEBRASKA
From 11-MAY-14 07:00:00 to 12-MAY-14 07:00:00 (CST-6)
Location: BRADSHAW
Property damage: 0.00K
Crop damage: 0.00K
Reported by: COOP Observer

The 24 hour rainfall total reported from Sunday through Monday morning was 3.08 inches.

Hail in ADAMS, NEBRASKA
From 11-MAY-14 14:17:00 to 11-MAY-14 14:27:00 (CST-6)
Location: HASTINGS
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Hail in ADAMS, NEBRASKA
From 11-MAY-14 14:19:00 to 11-MAY-14 14:22:00 (CST-6)
Location: HASTINGS
Magnitude: 0.88 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Penny to nickel size hail was reported.

Thunderstorm Wind in CLAY, NEBRASKA
From 11-MAY-14 14:47:00 to 11-MAY-14 14:47:00 (CST-6)
Location: GLENVILLE
Magnitude: 63.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Hail in HAMILTON, NEBRASKA
From 11-MAY-14 15:26:00 to 11-MAY-14 15:26:00 (CST-6)
Location: AURORA
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Hail in HAMILTON, NEBRASKA
From 11-MAY-14 15:52:00 to 11-MAY-14 15:52:00 (CST-6)
Location: GILTNER
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Hail in HAMILTON, NEBRASKA
From 11-MAY-14 16:03:00 to 11-MAY-14 16:13:00 (CST-6)
Location: AURORA
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Hail in WEBSTER, NEBRASKA
From 11-MAY-14 15:35:00 to 11-MAY-14 15:35:00 (CST-6)
Location: BLADEN
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Tornado in YORK, NEBRASKA
From 11-MAY-14 16:04:00 to 11-MAY-14 16:06:00 (CST-6)
Location: MC COOL JCT
Tornado F-scale: EF0
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

This tornado actually moved southwest and was eventually engulfed into the main Cordova tornado. No damage was reported with this tornado.

Tornado in CLAY, NEBRASKA
From 11-MAY-14 14:26:00 to 11-MAY-14 14:27:00 (CST-6)
Location: DEWEESE
Tornado F-scale: EF0
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

This tornado was photographed by a local resident.  While the condensation funnel is not on the ground, the photos suggest the wind field likely reached the ground for a short time. The time and location were determined from the report and radar data. No damage was reported with this tornado.

Hail in ADAMS, NEBRASKA
From 11-MAY-14 14:30:00 to 11-MAY-14 14:30:00 (CST-6)
Location: HASTINGS
Magnitude: 1.75 
Property damage: 75.00K
Crop damage: 750.00K
Reported by: Law Enforcement

Hail in CLAY, NEBRASKA
From 11-MAY-14 14:45:00 to 11-MAY-14 14:45:00 (CST-6)
Location: GLENVILLE
Magnitude: 2.50 
Property damage: 150.00K
Crop damage: 1.50M
Reported by: Trained Spotter

Ping pong to tennis ball size hail was reported.

Tornado in CLAY, NEBRASKA
From 11-MAY-14 14:50:00 to 11-MAY-14 15:25:00 (CST-6)
Location: FAIRFIELD
Tornado F-scale: EF3
Property damage: 12.50M
Crop damage: 0.00K
Reported by: NWS Storm Survey

This tornado was reported initially as a multi-vortex tornado for several miles before taking on a more traditional look south of Saronville, where it was described as a wedge tornado. Based upon reports and video, it appears the entire mesocyclone of the storm was near ground level southwest of Sutton.  It was one of the strongest tornado of the day in south central Nebraska, rated an EF3 with the peak wind estimated to be 150 MPH. Rear flank downdraft winds resulted in damage on the south side of the tornado track and in addition to the damage to Sutton itself, areas east of Clay Center, southwest of Sutton through northwest of Grafton were affected.  Power poles and trees were damaged or snapped, irrigation pivots were overturned, and a few homes and outbuildings suffered damage.
Damage from this tornado was first noted north of Fairfield, where large tree limbs were knocked down and power poles broken.  The tornado shifted mainly east across Highway 14 south of Clay Center, with additional tree damage as well as irrigation pivots overturned.  It then started to move to the northeast, crossing Highway 41 east of Clay Center and Highway 6 a few miles west of Sutton, but powerful rear flank downdraft winds of 100 mph hammered Sutton and areas south-southwest of town, causing widespread property damage.  Moving in between Saronville and Sutton, the tornado then started a more east-northeast path, crossing Road 6 north of Sutton before dissipating approximately 5 miles northeast of town.
As the tornado approached and crossed Highway 6 it intensified to it strongest point.  Damage peaked a few miles north of Sutton, where the EF-3 rating was assigned, resulting from the destruction of a home.  Elsewhere along the path, a few other homes sustained less significant damage than the one north of Sutton, and a number of other outbuildings and grain bins were also damaged or destroyed.  Many trees were damaged, destroyed or contained debris (mainly from destroyed grain bins), irrigation pivots were overturned and power poles broken.

Hail in HAMILTON, NEBRASKA
From 11-MAY-14 15:05:00 to 11-MAY-14 15:35:00 (CST-6)
Location: STOCKHAM
Magnitude: 1.50 
Property damage: 25.00K
Crop damage: 250.00K
Reported by: Trained Spotter

Quarter to half dollar size hail was reported.

Tornado in FILLMORE, NEBRASKA
From 11-MAY-14 15:25:00 to 11-MAY-14 15:28:00 (CST-6)
Location: GRAFTON
Tornado F-scale: EF3
Property damage: 1.50M
Crop damage: 0.00K
Reported by: NWS Storm Survey

This is the continuation of the EF3 tornado that started in Clay County northwest of Fairfield.
This tornado was reported initially as a multi-vortex tornado for several miles before taking on a more traditional look south of Saronville, where it was described as a wedge tornado. Based upon reports and video, it appears the entire mesocyclone of the storm was near ground level southwest of Sutton.  It was one of the strongest tornado of the day in south central Nebraska, rated an EF3 with the peak wind estimated to be 150 MPH. Rear flank downdraft winds resulted in damage on the south side of the tornado track and in addition to the damage to Sutton itself, areas east of Clay Center, southwest of Sutton through northwest of Grafton were affected.  Power poles and trees were damaged or snapped, irrigation pivots were overturned, and a few homes and outbuildings suffered damage.
Damage from this tornado was first noted north of Fairfield, where large tree limbs were knocked down and power poles broken.  The tornado shifted mainly east across Highway 14 south of Clay Center, with additional tree damage as well as irrigation pivots overturned.  It then started to move to the northeast, crossing Highway 41 east of Clay Center and Highway 6 a few miles west of Sutton, but powerful rear flank downdraft winds of 100 mph hammered Sutton and areas south-southwest of town, causing widespread property damage.  Moving in between Saronville and Sutton, the tornado then started a more east-northeast path, crossing Road 6 north of Sutton before dissipating approximately 5 miles northeast of town.
As the tornado approached and crossed Highway 6 it intensified to it strongest point.  Damage peaked a few miles north of Sutton, where the EF-3 rating was assigned, resulting from the destruction of a home.  Elsewhere along the path, a few other homes sustained less significant damage than the one north of Sutton, and a number of other outbuildings and grain bins were also damaged or destroyed.  Many trees were damaged, destroyed or contained debris (mainly from destroyed grain bins), irrigation pivots were overturned and power poles broken.

Tornado in FILLMORE, NEBRASKA
From 11-MAY-14 15:25:00 to 11-MAY-14 15:26:00 (CST-6)
Location: GRAFTON
Tornado F-scale: EF0
Property damage: 0.00K
Crop damage: 0.00K
Reported by: NWS Storm Survey

This tornado location was determined from video and chaser reports. An experienced meteorologist and others have reported that this tornado rotated anti-cyclonically, or the opposite direction most tornadoes rotate. Radar imagery and video suggest the anti-cyclonic circulation could have occurred, although the rotational direction could not be confirmed via field survey. No damage was reported with this tornado.

Tornado in FILLMORE, NEBRASKA
From 11-MAY-14 15:25:00 to 11-MAY-14 15:41:00 (CST-6)
Location: GRAFTON
Tornado F-scale: EF2
Property damage: 3.50M
Crop damage: 0.00K
Reported by: NWS Storm Survey

This tornado traveled rural areas of northern Fillmore County, bumping the York County line along the way. It touched down a few miles north-northwest of Grafton and lifted a few miles north-northeast of Fairmont. One home suffered damage when part of the roof was torn away, while another older home was pushed approximately 30 feet off of its foundation. There was widespread power pole and tree damage, with some trees containing debris from grain bins, and a number of irrigation pivots were overturned. The peak wind with this tornado was estimated to be 120 MPH. South of the main tornado track, strong rear flank downdraft winds resulted in additional power pole and irrigation pivot damage, and an outbuilding suffered damage near Highway 81 north of Fairmont.

Hail in ADAMS, NEBRASKA
From 11-MAY-14 15:29:00 to 11-MAY-14 15:32:00 (CST-6)
Location: HASTINGS
Magnitude: 1.50 
Property damage: 50.00K
Crop damage: 0.00K
Reported by: NWS Employee

Quarter to half dollar size hail was reported.

Tornado in FILLMORE, NEBRASKA
From 11-MAY-14 15:40:00 to 11-MAY-14 15:48:00 (CST-6)
Location: FAIRMONT
Tornado F-scale: EF1
Property damage: 150.00K
Crop damage: 0.00K
Reported by: NWS Storm Survey

This tornado traveled rural areas and was witnessed by several storm chasers and experienced meteorologists. Video evidence, eyewitness accounts, radar imagey and even some of the damage confirm this tornado rotated anti-cyclonically. Damage along the path of the tornado included a grain bin and an old outbuilding being pushed off of their foundations, along with a roof partially blown off of another outbuilding. Numerous irrigation pivots were overturned, and there was plenty of tree damage. There was a home with minor roof damage. The peak wind with this tornado was estimated to be 90 MPH.

Tornado in FILLMORE, NEBRASKA
From 11-MAY-14 15:57:00 to 11-MAY-14 16:00:00 (CST-6)
Location: EXETER
Tornado F-scale: EF3
Property damage: 7.50M
Crop damage: 0.00K
Reported by: NWS Storm Survey

This tornado was the second to be rated an EF3 that affected south central Nebraska, starting in far northern Fillmore County before traversing a portion of York County and passing north of Cordova in Seward County. Damage along the track in Fillmore County was widespread, including one home which was totally destroyed. All 6 occupants took shelter in the basement. Another home suffered less significant damage, but outbuildings on the same property were destroyed. Also along the path of this tornado, and to the south of the path where rear flank downdraft winds occurred, numerous irrigation pivots were overturned, power poles were broken as well as trees and grain bins either damaged or destroyed. The strongest and widest time of this tornado occurred in Seward County, with a peak wind estimated to be 140 MPH and a maximum width of 2,640 yards, or 1.5 miles.

Flash Flood in YORK, NEBRASKA
From 11-MAY-14 16:00:00 to 11-MAY-14 22:00:00 (CST-6)
Location: HENDERSON
Flood cause: Heavy Rain
Property damage: 200.00K
Crop damage: 0.00K
Reported by: Law Enforcement

A widespread swath of 3 to at least 4 inches of rain fell, resulting in the closure of numerous county roads across southern portions of York County.

Tornado in YORK, NEBRASKA
From 11-MAY-14 16:58:00 to 11-MAY-14 17:00:00 (CST-6)
Location: MC COOL JCT
Tornado F-scale: EF1
Property damage: 60.00K
Crop damage: 0.00K
Reported by: NWS Storm Survey

This tornado started just under one mile inside York County and quickly strengthened, destroying a grain bin and power poles on the York and Seward County line. This tornado was only in York County for a short time, with most of its damage occurring in Seward County. Damage along the path of the tornado in York County included overturned irrigation pivots, broken power poles, and the destruction of grain bins. The peak wind with this tornado was estimated to be 90 MPH.

Hail in HAMILTON, NEBRASKA
From 11-MAY-14 16:32:00 to 11-MAY-14 16:32:00 (CST-6)
Location: STOCKHAM
Magnitude: 1.50 
Property damage: 25.00K
Crop damage: 150.00K
Reported by: Trained Spotter

Tornado in YORK, NEBRASKA
From 11-MAY-14 16:00:00 to 11-MAY-14 16:07:00 (CST-6)
Location: MC COOL JCT
Tornado F-scale: EF3
Property damage: 1.50M
Crop damage: 0.00K
Reported by: NWS Storm Survey

This is a continuation of the tornado that started in northern Fillmore County. This tornado was the second to be rated an EF3 that affected south central Nebraska, starting in far northern Fillmore County before traversing a portion of York County and passing north of Cordova in Seward County. Damage along the track in Fillmore County was widespread, including one home which was totally destroyed. All 6 occupants took shelter in the basement. Another home suffered less significant damage, but outbuildings on the same property were destroyed. Also along the path of this tornado, and to the south of the path where rear flank downdraft winds occurred, numerous irrigation pivots were overturned, power poles were broken as well as trees and grain bins either damaged or destroyed. The strongest and widest time of this tornado occurred in Seward County, with a peak wind estimated to be 140 MPH and a maximum width of 2,640 yards, or 1.5 miles.

Hail in HARLAN, NEBRASKA
From 11-MAY-14 02:45:00 to 11-MAY-14 02:45:00 (CST-6)
Location: ORLEANS
Magnitude: 1.50 
Property damage: 50.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Hail in ADAMS, NEBRASKA
From 11-MAY-14 14:10:00 to 11-MAY-14 14:20:00 (CST-6)
Location: AYR
Magnitude: 1.50 
Property damage: 50.00K
Crop damage: 0.00K
Reported by: Public

Hail in ADAMS, NEBRASKA
From 11-MAY-14 14:25:00 to 11-MAY-14 14:35:00 (CST-6)
Location: HASTINGS
Magnitude: 2.00 
Property damage: 250.00K
Crop damage: 0.00K
Reported by: Storm Chaser

Quarter to hen egg size hail was reported.