The evening hours of Memorial Day 2011 featured the most widespread damaging wind event of the spring severe weather season across South Central Nebraska, as a narrow, intense line of storms marched from west to east across the entire area. Along nearly the entire length of this north-south oriented squall line were estimated or measured wind gusts of 60-80 MPH, with automated equipment at the Lexington airport recording the highest-known measured gust of 90 MPH. As a result, widespread wind damage primarily to trees, power lines and outbuildings occurred across multiple counties. Although there several preliminary reports of brief tornadoes along the leading edge of the squall line, including one near Cozad early in the evening, radar data along with photographic and video evidence suggests that the vast majority of these reports were actually gustnadoes, which are brief, but sometimes strong circulations associated with outflow and not connected to cloud base rotation. Most of these gustnado reports focused west of the Highway 281 corridor. In addition, there were also sporadic reports of quarter size hail, but damaging straight-line wind along the surging outflow was the main story by far. Just to name a few, wind highlights included: a measured 74 MPH gust at Central Nebraska Regional Airport in Grand Island with several reports of structural damage within the city including a destroyed mini-storage building; a measured gust to 83 MPH at the Ord airport with considerable damage to a hangar; three empty grain bins blown off their foundations and an unsecured trailer rolled near Strang in Fillmore County.
Focusing on timing, the initial severe storm development took place across north central Nebraska during mid-afternoon, with the developing severe squall line first creeping southward into western Dawson County around 7 PM CDT. Thereafter, the line continued to build south into Kansas as it marched east, crossing the Highway 281 corridor mainly between 9 and 10 PM CDT, and finally exiting eastern portions of South Central Nebraska between 11 PM and midnight CDT.
The synoptic and mesoscale environment was certainly ripe for a damaging, linear wind event. Earlier in the day, a strong pressure gradient brought hours of sustained 30-40 MPH winds and frequent gusts of 45-55 MPH to South Central Nebraska, as a 994 millibar surface low pressure system organized near the Colorado-Kansas border. Aloft, a powerful, negatively tilted upper level trough centered across the Central and Northern Rockies gradually ejected northeast toward the Northern Plains, allowing considerable large scale forcing and increasing wind fields to overspread Nebraska, including 60-80 knot southwesterly flow at 500 millibars. Lower in the atmosphere, southerly low-level jet winds at 850 millibars increased to around 60 knots. At the surface, a pronounced cold front sliced through the area, providing sharp linear forcing for development of the squall line. Mesoscale severe weather parameters early in the evening included mixed layer CAPE values around 2500 J/kg, and deep-layer vertical wind shear generally 50-70 knots. As the evening wore on, 0-1 kilometer low-level bulk shear ramped up to notably strong values of 40-50 knots, providing a very favorable environment for damaging winds and gustnadoes.

Thunderstorm Wind in SHERMAN, NEBRASKA
From 30-MAY-11 19:43:00 to 30-MAY-11 19:46:00 (CST-6)
Location: LOUP CITY
Magnitude: 61.00 EG
Property damage: 50.00K
Crop damage: 0.00K
Reported by: Amateur Radio

Wind gusts were estimated at 70 MPH, resulting in a large tree branch approximately 18 inches in diameter to fall onto a vehicle in Loup City.

Thunderstorm Wind in BUFFALO, NEBRASKA
From 30-MAY-11 19:47:00 to 30-MAY-11 19:51:00 (CST-6)
Location: AMHERST
Magnitude: 70.00 EG
Property damage: 500.00K
Crop damage: 250.00K
Reported by: Storm Chaser

Wind gusts were estimated at 80 MPH.  Damage later reported in the area by the Emergency Manager included outbuildings damaged, power poles knocked over, and overturned pivots.

Thunderstorm Wind in BUFFALO, NEBRASKA
From 30-MAY-11 19:51:00 to 30-MAY-11 19:51:00 (CST-6)
Location: RAVENNA
Magnitude: 61.00 EG
Property damage: 75.00K
Crop damage: 0.00K
Reported by: Public

Wind gusts were estimated at 70 MPH, causing roof damage to a local shop.

Thunderstorm Wind in FRANKLIN, NEBRASKA
From 30-MAY-11 20:10:00 to 30-MAY-11 20:10:00 (CST-6)
Location: FRANKLIN
Magnitude: 61.00 EG
Property damage: 150.00K
Crop damage: 250.00K
Reported by: Newspaper

Damage reports included tree limbs knocked down, a couple power poles knocked over resulting in power outages, roof and carport damage in town, and a storage unit damage approximately 2 miles south of town.

Thunderstorm Wind in HOWARD, NEBRASKA
From 30-MAY-11 20:15:00 to 30-MAY-11 20:17:00 (CST-6)
Location: ST PAUL
Magnitude: 61.00 EG
Property damage: 100.00K
Crop damage: 0.00K
Reported by: Newspaper

Damage reports included roof, gutter and tree damage, with one tree landing on a vehicle in town.  Three outbuildings were also damaged.

Thunderstorm Wind in HALL, NEBRASKA
From 30-MAY-11 20:20:00 to 30-MAY-11 20:30:00 (CST-6)
Location: GRAND IS
Magnitude: 70.00 EG
Property damage: 750.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Damage reported from the wind gusts estimated near 80 MPH included a local housing company having a show home destroyed when it rolled, siding and window damage to a number of homes and recreational vehicles, and vehicle and roof damage at a local manufacturing plant.  Tree damage was reported across town.  Near the intersection of Highways 30 and 281, a personal storage facility was destroyed and a power pole was snapped and fell on a business. West of town, pivots were overturned and a number of train cars were derailed.

Thunderstorm Wind in HAMILTON, NEBRASKA
From 30-MAY-11 20:53:00 to 30-MAY-11 20:55:00 (CST-6)
Location: GILTNER
Magnitude: 59.00 MG
Property damage: 100.00K
Crop damage: 0.00K
Reported by: AWOS

Damage reports included 2 pivots overturned 6 miles south of Giltner and 4 to 6 inch tree limbs knocked down in Aurora.

Thunderstorm Wind in NUCKOLLS, NEBRASKA
From 30-MAY-11 21:29:00 to 30-MAY-11 21:31:00 (CST-6)
Location: SUPERIOR
Magnitude: 61.00 EG
Property damage: 50.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Wind gusts were estimated at 70 MPH in Superior, with 6 inch tree limbs and small outbuildings damaged 3.5 miles east of town.

Thunderstorm Wind in FILLMORE, NEBRASKA
From 30-MAY-11 21:50:00 to 30-MAY-11 21:50:00 (CST-6)
Location: STRANG
Magnitude: 61.00 EG
Property damage: 125.00K
Crop damage: 250.00K
Reported by: Emergency Manager

Wind gusts were estimated at 70 MPH, with damaged reports including 3 empty grain bins blown off their foundation, an unsecured trailer rolled off its foundation, and some irrigation pipe blown from their location.

Thunderstorm Wind in POLK, NEBRASKA
From 30-MAY-11 21:50:00 to 30-MAY-11 21:50:00 (CST-6)
Location: SHELBY
Magnitude: 56.00 EG
Property damage: 25.00K
Crop damage: 0.00K
Reported by: COOP Observer

Wind gusts were estimated at 65 MPH, knocking down tree limbs up to 8 inches in diameter and snapping two healthy trees.

Hail in DAWSON, NEBRASKA
From 30-MAY-11 18:28:00 to 30-MAY-11 18:28:00 (CST-6)
Location: COZAD
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Thunderstorm Wind in VALLEY, NEBRASKA
From 30-MAY-11 19:00:00 to 30-MAY-11 19:00:00 (CST-6)
Location: ARCADIA
Magnitude: 52.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: COOP Observer

Wind gusts were estimated at 60 MPH, knocking down tree limbs between 5 and 6 inches in diameter.

Thunderstorm Wind in BUFFALO, NEBRASKA
From 30-MAY-11 19:30:00 to 30-MAY-11 19:30:00 (CST-6)
Location: MILLER
Magnitude: 61.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: COOP Observer

Damage to a local church was reported.

Hail in SHERMAN, NEBRASKA
From 30-MAY-11 19:46:00 to 30-MAY-11 19:46:00 (CST-6)
Location: LOUP CITY
Magnitude: 0.88 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Thunderstorm Wind in HOWARD, NEBRASKA
From 30-MAY-11 20:30:00 to 30-MAY-11 20:30:00 (CST-6)
Location: DANNEBROG
Magnitude: 65.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Wind gusts were estimated at 75 MPH.

Thunderstorm Wind in HAMILTON, NEBRASKA
From 30-MAY-11 20:45:00 to 30-MAY-11 20:45:00 (CST-6)
Location: PHILLIPS
Magnitude: 52.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Fire Department/Rescue

Wind gusts were estimated at 60 MPH.

Thunderstorm Wind in HALL, NEBRASKA
From 30-MAY-11 20:48:00 to 30-MAY-11 20:48:00 (CST-6)
Location: (GRI)GRAND IS RGNL A
Magnitude: 51.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: ASOS

Hail in WEBSTER, NEBRASKA
From 30-MAY-11 21:07:00 to 30-MAY-11 21:07:00 (CST-6)
Location: GUIDE ROCK
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Thunderstorm Wind in WEBSTER, NEBRASKA
From 30-MAY-11 21:11:00 to 30-MAY-11 21:11:00 (CST-6)
Location: GUIDE ROCK
Magnitude: 52.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Wind gusts were estimated at 60 MPH.

Hail in CLAY, NEBRASKA
From 30-MAY-11 21:35:00 to 30-MAY-11 21:35:00 (CST-6)
Location: HARVARD
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Thunderstorm Wind in HALL, NEBRASKA
From 30-MAY-11 20:30:00 to 30-MAY-11 20:30:00 (CST-6)
Location: (GRI)GRAND IS RGNL A
Magnitude: 64.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: ASOS

Thunderstorm Wind in ADAMS, NEBRASKA
From 30-MAY-11 20:15:00 to 30-MAY-11 20:15:00 (CST-6)
Location: HOLSTEIN
Magnitude: 56.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Newspaper

Wind gusts were estimated at 60 to 65 MPH.

Thunderstorm Wind in KEARNEY, NEBRASKA
From 30-MAY-11 20:10:00 to 30-MAY-11 20:11:00 (CST-6)
Location: NORMAN
Magnitude: 65.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Newspaper

Damage reports included 3 overturned pivots and 12 power poles knocked down.

Tornado in DAWSON, NEBRASKA
From 30-MAY-11 18:34:00 to 30-MAY-11 18:36:00 (CST-6)
Location: (CZD)COZAD MUNI ARPT
Tornado F-scale: EF0
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Emergency Manager

A brief tornado was spotted near Cozad. No damage was reported.

Hail in DAWSON, NEBRASKA
From 30-MAY-11 18:05:00 to 30-MAY-11 18:05:00 (CST-6)
Location: GOTHENBURG
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Hail in DAWSON, NEBRASKA
From 30-MAY-11 18:19:00 to 30-MAY-11 18:19:00 (CST-6)
Location: COZAD
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Thunderstorm Wind in GOSPER, NEBRASKA
From 30-MAY-11 18:40:00 to 30-MAY-11 18:40:00 (CST-6)
Location: ELWOOD
Magnitude: 52.00 EG
Property damage: 35.00K
Crop damage: 0.00K
Reported by: COOP Observer

Wind gusts estimated at 60 MPH with damage to several cattle sheds was reported.

Thunderstorm Wind in DAWSON, NEBRASKA
From 30-MAY-11 18:52:00 to 30-MAY-11 18:52:00 (CST-6)
Location: COZAD
Magnitude: 65.00 EG
Property damage: 75.00K
Crop damage: 0.00K
Reported by: Storm Chaser

Wind gusts were estimated between 70 and 75 MPH.

Thunderstorm Wind in DAWSON, NEBRASKA
From 30-MAY-11 18:55:00 to 30-MAY-11 18:55:00 (CST-6)
Location: LEXINGTON ARPT
Magnitude: 78.00 MG
Property damage: 500.00K
Crop damage: 250.00K
Reported by: AWOS

Wind gusts up to 90 MPH caused tree damage, knocked down power lines and overturned pivots in the area.  On the north side of Lexington, a fence at a ballfield was damaged.

Thunderstorm Wind in VALLEY, NEBRASKA
From 30-MAY-11 19:00:00 to 30-MAY-11 19:10:00 (CST-6)
Location: ORD
Magnitude: 72.00 MG
Property damage: 1.00M
Crop damage: 250.00K
Reported by: ASOS

Damage from wind gusts near and in excess of 80 MPH caused considerable damage to area grain bins and outbuildings, and also overturned pivots.  At the Ord Airport, the roof was peeled off of one of the hangars, and one side of the building was ripped away.

Thunderstorm Wind in BUFFALO, NEBRASKA
From 30-MAY-11 19:33:00 to 30-MAY-11 19:34:00 (CST-6)
Location: RIVERDALE
Magnitude: 78.00 EG
Property damage: 500.00K
Crop damage: 250.00K
Reported by: NWS Employee

Wind gusts were estimated at 80 to 90 MPH, resulting in overturned pivots and knocked down power lines, with power flashes and outages also reported.