During a June that featured a below-average quantity of severe weather within South Central Nebraska, this late Friday afternoon-night episode ended up being the most widespread round of the month. The majority of severe storms targeted areas west of the Highway 281 corridor, mainly producing damaging winds and locally heavy rainfall/flooding, along with a few reports of large hail. Some of the more noteworthy wind and/or wind damage reports included: a measured 75 MPH gust in the Loomis area with power lines and trees down, measured gusts of 70 MPH near Norman and 68 MPH near Kearney, estimated 70 MPH winds in Beaver City and estimated 60 MPH winds in Lexington with 8-10 inch diameter tree limbs down. While most wind damage occurred between 7-9 p.m. CDT in close proximity to actual severe storms, strong to marginally-severe outflow winds managed to surge 20+ miles out ahead of the primary precipitation cores around sunset. This outflow yielded measured gusts around 50 MPH at the Grand Island and Hastings airports and even toppled a 10-inch diameter tree on the eastern fringe of Hastings. Later in the night, a completely separate, southward-rushing storm complex entered northeastern portions of the local area (counties mainly east of Highway 281 and along/north of Interstate 80) in a weakening state, but still produced northerly outflow of 50+ MPH, including 55 MPH measured at the York airport shortly after 1 a.m. CDT. There were fewer reports of large hail during this event, but stones up to golf ball size were confirmed near Ashton early in the evening, and also near Ord closer to sunset (quarter to ping pong ball size in Ord itself).
Turning to hydrology issues, although they were fairly isolated/localized in nature, there were three bulls eyes of heavy, radar-estimated rainfall of at least 1.50-3.00 that fell in a short time and produced verified flooding. Going in chronological order, the first pocket of heavy rain targeted east-central Sherman County as a nearly-stationary storm parked itself overhead for roughly 2.5 hours between 4:30-7:00 p.m. CDT. This resulted in flooding of Deer Creek, which covered a portion of at least one rural road between Rockville and Ashton for a time. Around the time rain started easing up over Sherman County, additional pockets of short-fused heavy rain focused over portions of central Dawson and west-central Phelps counties mainly between 6:30-8:30 p.m. CDT, resulting in several county road closures in the Cozad/Lexington and Bertrand/Loomis areas. Although there were almost no official gauge totals from the very-heaviest rain zones, Lexington airport tallied 2.56. Outside of these three aforementioned pockets of very heavy rain, the majority of South Central Nebraska received no more than 0.50-1.00 during this event, and hardly even a drop within most central counties along the Highway 281 corridor.
Taking a closer look at timing, the first, isolated storms of the day flared up during the peak heating hours of 3-6 p.m. CDT, primarily within Sherman and Dawson counties. Then, during the ensuing four hours through 10 p.m. CDT, storm coverage greatly increased within the western half of South Central Nebraska, both as a result of new development along local outflow boundaries and also from additional storms expanding northeastward into the area out of southwest Nebraska and northwest Kansas. After 10 p.m. CDT, the onset of diurnal cooling resulted in a steady weakening/dissipation of the main round of afternoon/evening convection. However, primarily between 12-2 a.m. CDT on the 18th, a completely separate southward-tracking storm complex entered mainly northeastern portions of South Central Nebraska in a steadily-weakening state. Through the remainder of the night, scattered weak thunderstorms lingered over eastern portions of the area (especially within the Highway 81 counties), but by sunrise on the 18th nearly all of South Central Nebraska was rain-free. This was a somewhat sneaky severe weather event considering that mid-upper level forcing and deep-layer wind shear were quite weak by mid-June standards (no more than 15-20 knots), initially limiting the overall magnitude/coverage of severe storms. However, this lack of forcing/shear was clearly compensated for by a potent level of instability/CAPE, climbing to at least 3000-4000 J/kg during the afternoon. These lofty instability values were not surprising considering that this was one of the overall-hottest, most humid days of summer 2016 within South Central Nebraska as temperatures generally topped out 96-100 F in the presence of dewpoints in the mid-60s to low-70s. Because of this high instability/low shear setup, initially isolated multicell convection quickly became outflow-dominant, subsequently igniting increasingly-widespread storm development along a plethora of merging outflow boundaries. In the mid-upper levels, the weak flow and lack of large-scale forcing over the Central Plains was due to a broad ridge axis stretched from northern Mexico all the way into southeast Canada. At the surface, there were no pronounced boundaries of note over the local area, although a somewhat subtle inverted trough extended across Nebraska from southwest-to-northeast.

Hail in SHERMAN, NEBRASKA
From 17-JUN-16 17:10:00 to 17-JUN-16 17:10:00 (CST-6)
Location: ASHTON
Magnitude: 1.75 
Property damage: 150.00K
Crop damage: 1.00M
Reported by: Trained Spotter

Quarter to golf ball size hail fell from a nearly stationary storm in the Ashton area. The actual duration of hail was likely at least several minutes, but ground-truth duration details were not available for any particular location.

Flood in SHERMAN, NEBRASKA
From 17-JUN-16 20:00:00 to 18-JUN-16 06:00:00 (CST-6)
Location: ASHTON
Flood cause: Heavy Rain
Property damage: 5.00K
Crop damage: 0.00K
Reported by: NWS Employee

A small creek experienced significant flooding, flooding at least one gravel county road five miles north of Rockville near the intersection of Rockville Road and 784 Road. Doppler radar estimates indicated that two to four inches of rain fell mainly between 4:30-7:00 p.m. CDT.

Flash Flood in SHERMAN, NEBRASKA
From 17-JUN-16 18:00:00 to 17-JUN-16 20:00:00 (CST-6)
Location: ASHTON
Flood cause: Heavy Rain
Property damage: 5.00K
Crop damage: 0.00K
Reported by: NWS Employee

A small creek experienced significant flooding, flooding at least one gravel county road five miles north of Rockville near the intersection of Rockville Road and 784 Road. Doppler radar estimates indicated that two to four inches of rain fell mainly between 4:30-7:00 p.m. CDT.

Flash Flood in PHELPS, NEBRASKA
From 17-JUN-16 20:20:00 to 17-JUN-16 23:20:00 (CST-6)
Location: BERTRAND
Flood cause: Heavy Rain
Property damage: 10.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Several county roads were flooded and were closed in between Loomis and Bertrand.

Hail in FURNAS, NEBRASKA
From 17-JUN-16 18:16:00 to 17-JUN-16 18:16:00 (CST-6)
Location: BEAVER CITY
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 100.00K
Reported by: Trained Spotter

Heavy rain and hail up to the size of quarters occurred.

Hail in VALLEY, NEBRASKA
From 17-JUN-16 20:46:00 to 17-JUN-16 20:50:00 (CST-6)
Location: ARCADIA
Magnitude: 1.75 
Property damage: 25.00K
Crop damage: 175.00K
Reported by: Trained Spotter

Wind gusts up to 50 mph occurred along with dime to golf ball size hail.

Thunderstorm Wind in FURNAS, NEBRASKA
From 17-JUN-16 18:20:00 to 17-JUN-16 18:20:00 (CST-6)
Location: BEAVER CITY
Magnitude: 61.00 EG
Property damage: 150.00K
Crop damage: 150.00K
Reported by: Trained Spotter

An estimated 70 mph thunderstorm wind gust occurred. Part of a tree fell on a house. Also, dime size hail and torrential rain occurred.

Thunderstorm Wind in PHELPS, NEBRASKA
From 17-JUN-16 18:35:00 to 17-JUN-16 18:35:00 (CST-6)
Location: LOOMIS
Magnitude: 61.00 EG
Property damage: 150.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Six power poles and several trees were reported down, along with irrigation pivots, in an area north of Loomis near the intersection of G and 739 Roads.

Thunderstorm Wind in ADAMS, NEBRASKA
From 17-JUN-16 20:15:00 to 17-JUN-16 20:15:00 (CST-6)
Location: HASTINGS
Magnitude: 56.00 EG
Property damage: 150.00K
Crop damage: 0.00K
Reported by: NWS Employee

A 30 foot tall, 10 inch diameter tree was blown down on the far east side of Hastings. Also, a flag pole was blown down.

Thunderstorm Wind in DAWSON, NEBRASKA
From 17-JUN-16 18:37:00 to 18-JUN-16 00:37:00 (CST-6)
Location: LEXINGTON
Magnitude: 52.00 EG
Property damage: 150.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Tree limbs that were 8 to 10 inches in diameter were blown down.

Thunderstorm Wind in PHELPS, NEBRASKA
From 17-JUN-16 18:55:00 to 17-JUN-16 18:55:00 (CST-6)
Location: LOOMIS
Magnitude: 65.00 MG
Property damage: 150.00K
Crop damage: 0.00K
Reported by: Emergency Manager

This wind gust was measured 5 miles north of Loomis.

Thunderstorm Wind in KEARNEY, NEBRASKA
From 17-JUN-16 19:33:00 to 17-JUN-16 19:40:00 (CST-6)
Location: AXTELL
Magnitude: 61.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Measured wind gusts of 62 to 68  mph occurred near the Highway 44 corridor in western Kearney County.

Flash Flood in DAWSON, NEBRASKA
From 17-JUN-16 19:40:00 to 17-JUN-16 23:40:00 (CST-6)
Location: COZAD
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Paved roads were flooded about five miles south of Cozad near the intersection of Road 755 and Avenue 423. This stretch of road was closed.

Thunderstorm Wind in GOSPER, NEBRASKA
From 17-JUN-16 18:20:00 to 17-JUN-16 18:20:00 (CST-6)
Location: ELWOOD
Magnitude: 52.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: COOP Observer

Cooperative observer estimated 60 MPH wind, resulting in small branches broken in trees and bushes.

Thunderstorm Wind in KEARNEY, NEBRASKA
From 17-JUN-16 19:38:00 to 17-JUN-16 19:38:00 (CST-6)
Location: NORMAN
Magnitude: 61.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Hail in SHERMAN, NEBRASKA
From 17-JUN-16 16:50:00 to 17-JUN-16 16:50:00 (CST-6)
Location: ASHTON
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Hail was mostly nickel size with a few up to quarters. The actual duration of hail was likely at least several minutes, but ground-truth duration details were not available for any particular location.