The pre-dawn hours of this Sunday featured a surprisingly-potent, southward-surging complex of severe thunderstorms that provoked considerable wind damage primarily within Sherman, Buffalo, Howard and Hall counties, and likely isolated wind damage in several nearby counties as well. Some of the worst impacts occurred in and near Ravenna, where estimated gusts to around 85 MPH downed numerous trees, some as large as 4-6 feet in diameter. Portions of the community were without power for several hours, and a few homes and vehicles also sustained damage. In Kearney, while damage was not widespread, three large trees crashed down on a trailer home causing substantial roof damage. Other communities that suffered wind damage (mainly to trees) included: Loup City, Pleasanton, Cairo, Boelus and Grand Island (although impacts were quite minimal on the grounds of the ongoing Nebraska State Fair). Once storms pushed south of the Interstate 80 corridor, most peak gusts checked in around or below 50 MPH, although a mesonet station near Nelson clocked a 60 MPH gust shortly before the strongest part of the complex departed southward into Kansas. As for rainfall, the majority of South Central Nebraska received at least 0.50-1.00, but localized pockets of mainly Valley, Sherman and Howard counties tallied 2+.
Breaking down event timing and evolution, the late evening featured a smattering of fairly weak storms here and there. However, the main event did not get even get underway until 2-3 a.m. CDT, as the beginning stages of a developing squall line took shape in far northern portions of South Central Nebraska, evolving from earlier activity that initiated in northern Nebraska. Over the next few hours, this linear complex surged south, wreaking the aforementioned wind damage and eventually assuming the form of a mature bow echo before departing into north central Kansas mainly between 5:30-6:30 a.m. CDT.
Although the severity of this late-night severe event was not well-anticipated, a chance of thunderstorms was in the forecast as the mid-upper levels featured a fairly compact shortwave trough diving out of SD into Nebraska in a north-northwest flow regime. Closer to the surface at 850 millibars, modest south-southwesterly flow resulted in decent low-level moisture convergence into central Nebraska, and at the surface, a weak cold front sagged southward across the state as the night wore on (eventually augmented by storm outflow). Once storms established a surging cold pool, the moisture-rich surface environment proved favorable to fostering severe wind gusts, with dewpoints averaging in the mid-60s to around 70 F. Around the time the damaging wind event ramped up, mesoscale analysis indicated most-unstable CAPE up to around 2000 j/kg and effective deep-layer wind shear around 40 knots.

Thunderstorm Wind in HOWARD, NEBRASKA
From 27-AUG-17 02:45:00 to 27-AUG-17 03:19:00 (CST-6)
Location: BOELUS
Magnitude: 61.00 EG
Property damage: 25.00K
Crop damage: 0.00K
Reported by: Public

Wind gusts estimated to be near 70 MPH resulted in tree damage across the area. Large tree limbs were downed along Highway 58 near Dannebrog. A large pine tree in Boelus had its top snapped off, with a large branch impaling the roof of a nearby house.

Thunderstorm Wind in SHERMAN, NEBRASKA
From 27-AUG-17 02:24:00 to 27-AUG-17 02:24:00 (CST-6)
Location: LOUP CITY
Magnitude: 61.00 EG
Property damage: 75.00K
Crop damage: 0.00K
Reported by: COOP Observer

Wind gusts estimated to be near 70 MPH resulted in some large trees being downed in Loup City, blocking a few streets.

Thunderstorm Wind in NUCKOLLS, NEBRASKA
From 27-AUG-17 04:24:00 to 27-AUG-17 04:24:00 (CST-6)
Location: NELSON
Magnitude: 52.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Thunderstorm Wind in BUFFALO, NEBRASKA
From 27-AUG-17 03:15:00 to 27-AUG-17 03:19:00 (CST-6)
Location: KEARNEY
Magnitude: 61.00 EG
Property damage: 75.00K
Crop damage: 5.00M
Reported by: Emergency Manager

Wind gusts were estimated to be near 70 MPH.  A trailer home was damaged when 3 trees  were downed.  Part of a tree knocked a hole through the roof, allowing water to get inside the home.

Thunderstorm Wind in HALL, NEBRASKA
From 27-AUG-17 02:55:00 to 27-AUG-17 03:30:00 (CST-6)
Location: CAIRO
Magnitude: 61.00 EG
Property damage: 75.00K
Crop damage: 5.00M
Reported by: Public

Wind gusts along this path were estimated to be between 60 and 70 MPH, with the strongest wind being in the Cairo area and generally a bit weaker in Grand Island. There were several reports of large tree limbs being downed in the area, some as large as 8-9 inches in diameter.

Thunderstorm Wind in BUFFALO, NEBRASKA
From 27-AUG-17 02:35:00 to 27-AUG-17 02:45:00 (CST-6)
Location: PLEASANTON
Magnitude: 74.00 EG
Property damage: 500.00K
Crop damage: 5.00M
Reported by: Emergency Manager

Wind gusts in the area were estimated to be near 85 MPH, based on damage reports. There was widespread tree damage reported, especially in the Ravenna area. Several large trees were downed, some 4 to 6 feet in diameter, and heavy equipment was needed to clear some roads. Power lines were also downed in the area and a few homes and vehicles were damaged.