Despite the absence of notable upper level forcing over South Central Nebraska, a lone severe thunderstorm developed within an extremely unstable airmass during the late afternoon, producing sporadic wind damage and small hail along the way. This storm first initiated and slowly intensified across eastern Franklin and southern Adams Counties between 530 and 630 PM CDT, and then tracked almost due northeast for several hours, finally exiting out of Merrick and Polk Counties near Silver Creek shortly after 10 PM CDT. As it tracked northeast, this storm took on characteristics of both a multicell and an outflow-dominant supercell, pulsing in intensity and occasionally undergoing splits. Estimated wind speeds reached 65 MPH at times, with some of the most noteworthy damage occurring within the city of Grand Island where large trees were uprooted in a cemetery, and a hole was blown in the roof of a fire station.
This severe storm first formed along the northern edge of a zone of steep-low level lapse rates extending out of Kansas, and in a very moist and unstable environment just north of a surface warm front. This airmass featured surface dewpoints well into the 70s, and mixed-layer CAPE values on the order of 4000 J/kg. Deep-layer vertical wind shear was quite weak, only around 20 knots or so due to the presence of weak mid and upper level flow associated with upper level ridging dominating the central and southeastern United States. The storm's motion to the northeast seemed to track along an elevated frontal boundary evident at 850 millibars.

Hail in ADAMS, NEBRASKA
From 15-JUL-11 17:55:00 to 15-JUL-11 17:55:00 (CST-6)
Location: HOLSTEIN
Magnitude: 0.75 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Hail was accompanied by 40 MPH wind gusts.

Thunderstorm Wind in MERRICK, NEBRASKA
From 15-JUL-11 20:40:00 to 15-JUL-11 20:40:00 (CST-6)
Location: SILVER CREEK
Magnitude: 52.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Wind gusts were estimated at 60 MPH.

Thunderstorm Wind in ADAMS, NEBRASKA
From 15-JUL-11 17:50:00 to 15-JUL-11 17:50:00 (CST-6)
Location: ROSELAND
Magnitude: 52.00 EG
Property damage: 50.00K
Crop damage: 0.00K
Reported by: Public

Wind gusts estimated at 60 MPH caused minor damage to a grain elevator and uprooted a tree in town.

Thunderstorm Wind in HALL, NEBRASKA
From 15-JUL-11 19:30:00 to 15-JUL-11 19:30:00 (CST-6)
Location: GRAND IS
Magnitude: 56.00 EG
Property damage: 150.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Wind gusts estmiated up to 65 MPH affected mainly the southern side of town, with the main damage suffered by trees at a cemetery near Stolley Park and Webb Roads.  A couple trees were uprooted and a few tree limbs were knocked down, which also brought down some power lines.  There was also minor roof damage at an area fire station and minor car damage at a car dealership.

Thunderstorm Wind in MERRICK, NEBRASKA
From 15-JUL-11 20:56:00 to 15-JUL-11 20:56:00 (CST-6)
Location: SILVER CREEK
Magnitude: 54.00 MG
Property damage: 25.00K
Crop damage: 0.00K
Reported by: Trained Spotter

A few tree limbs up to 6 inches in diameter and power lines were knocked down.