Although it only impacted a small percentage of the 24-county South Central Nebraska area, the large and intense supercell storm that marched south-southwestward for over 90 miles through several eastern counties on this Friday afternoon/early evening was likely the local area's most noteworthy individual storm of the 2020 convective season. In addition to dropping three fairly brief EF-0 tornadoes in southeastern Hamilton and northeastern Clay counties, its main calling card was large hail, with several reports of golf ball to slightly larger than baseball size stones in Clay/Nuckolls counties, and smaller hail to around quarter size as far north as Osceola. Interestingly, damaging winds were not a major player, with no ground-truth gusts in excess of 50 MPH. Focusing on specific storm reports, and starting with the three EF-0 tornadoes, they all occurred between 5-6 p.m. CDT, touching down briefly along a roughly 15-mile long corridor from near Interstate 80 a few miles south of Hampton, down to the Saronville area. Per storm surveys, the first two tornadoes were each on the ground for roughly 2 miles. While the majority of minor damage was confined to crops and trees, a lean-to shed was destroyed and a pivot overturned. As for the hail, the largest reported was 3 diameter between Clay Center and Harvard, but towns including Sutton and Nelson endured stones to at least tennis ball size. Flooding was not much of an issue, as the storm was progressive enough to keep rainfall amounts largely under one inch.
Breaking down the meteorological background and event timing, this was actually a fairly conditional severe weather setup for South Central Nebraska, with various pros and cons for/against robust activity. In the mid-upper levels, the local area resided a fair distance south of a vigorous shortwave trough swinging across the Dakotas towards northern MN, resulting in fairly limited forcing aloft. Also working against convection (especially widespread severe) was a plume of warm mid level temperatures, with 700 millibar values of 12-14C providing a healthy cap. On the other hand, low-level forcing was seasonably-strong, as a well-defined cold front slid southeastward into the area during the afternoon. Ahead of this boundary, a significantly-unstable airmass awaited, featuring temperatures in the upper 80s-low 90s F/dewpoints upper 60s-mid 70s F, yielding formidable mixed-layer CAPE around 4000 J/kg. This extreme instability, in the presence of sufficient deep-layer wind shear around 35 knots, clearly fostered a mesoscale environment capable of stout convection. As for what actually transpired, the main show was preceded by a broken line of non-severe, likely elevated storms that passed primarily through counties south of Interstate 80 and east of Highway 281 between 12:30-3:30 p.m. CDT. About the time this innocuous early afternoon activity was departing the local area to the southeast, a broken line of true, surface-based storms got going along the front in northeast Nebraska, with the southwestern-most cell building down into the far northeast corner of South Central Nebraska (eastern Nance/northeast Merrick/northern Polk counties) between 3-4 p.m. CDT. Within an hour thereafter, this tail end Charlie storm rapidly grew into a full-blown supercell over Polk/northern York counties, producing its first marginally-severe hail reports. During the following two hours (5-7 p.m. CDT), the storm anchored itself firmly to the surface front, with new updraft generation along its western edge promoting more of a southwestward propagation and causing it to grow larger in both intensity/size, becoming more of a supercell cluster. It was during this time that the brief tornadoes occurred along the storm's far western flank, likely driven by pronounced low-level vorticity stretching along the surface front. While the sporadic tornado touchdowns were brief, the storm continued to be a prolific hail-producer as it gradually exited the local area out of Nuckolls County into northern Kansas between 7-8 p.m. CDT, ending all South Central Nebraska convection for the night.

Hail in NUCKOLLS, NEBRASKA
From 14-AUG-20 17:37:00 to 14-AUG-20 17:37:00 (CST-6)
Location: NELSON
Magnitude: 1.75 
Property damage: 25.00K
Crop damage: 1.00M
Reported by: Social Media

Hail in NUCKOLLS, NEBRASKA
From 14-AUG-20 17:49:00 to 14-AUG-20 18:00:00 (CST-6)
Location: NELSON
Magnitude: 2.50 
Property damage: 300.00K
Crop damage: 3.00M
Reported by: Emergency Manager

Hail ranging in size from quarters to tennis balls was reported in and around Nelson.

Hail in CLAY, NEBRASKA
From 14-AUG-20 16:57:00 to 14-AUG-20 16:57:00 (CST-6)
Location: CLAY CENTER
Magnitude: 2.50 
Property damage: 100.00K
Crop damage: 2.00M
Reported by: Trained Spotter

Hail in CLAY, NEBRASKA
From 14-AUG-20 17:00:00 to 14-AUG-20 17:00:00 (CST-6)
Location: CLAY CENTER
Magnitude: 2.50 
Property damage: 100.00K
Crop damage: 2.00M
Reported by: Social Media

Hail in CLAY, NEBRASKA
From 14-AUG-20 17:10:00 to 14-AUG-20 17:15:00 (CST-6)
Location: CLAY CENTER
Magnitude: 2.75 
Property damage: 25.00K
Crop damage: 1.00M
Reported by: Social Media

Hail ranging in size from golf balls to baseballs was reported along this path. A vehicle's windshield was cracked approximately 6 miles southeast of Clay Center.

Hail in NUCKOLLS, NEBRASKA
From 14-AUG-20 17:35:00 to 14-AUG-20 17:35:00 (CST-6)
Location: LAWRENCE
Magnitude: 2.00 
Property damage: 100.00K
Crop damage: 3.00M
Reported by: Social Media

Tornado in HAMILTON, NEBRASKA
From 14-AUG-20 16:12:00 to 14-AUG-20 16:16:00 (CST-6)
Location: HAMPTON
Tornado F-scale: EF0
Property damage: 1.00K
Crop damage: 25.00K
Reported by: NWS Storm Survey

Minor crop and tree damage occurred. Debris was found in nearby powerlines. An old lean-to shed was destroyed.

Tornado in CLAY, NEBRASKA
From 14-AUG-20 16:36:00 to 14-AUG-20 16:40:00 (CST-6)
Location: ELDORADO
Tornado F-scale: EF0
Property damage: 30.00K
Crop damage: 40.00K
Reported by: NWS Storm Survey

A brief tornado continued from Hamilton County. Cedar tree damage occurred as the tornado crossed the county road into Clay County. A pivot was overturned and crop damage occurred into a converging pattern along the tornado path.

Hail in POLK, NEBRASKA
From 14-AUG-20 15:23:00 to 14-AUG-20 15:37:00 (CST-6)
Location: OSCEOLA
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Hail in CLAY, NEBRASKA
From 14-AUG-20 16:52:00 to 14-AUG-20 16:52:00 (CST-6)
Location: SARONVILLE
Magnitude: 1.25 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Hail in CLAY, NEBRASKA
From 14-AUG-20 17:10:00 to 14-AUG-20 17:10:00 (CST-6)
Location: HARVARD
Magnitude: 3.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Social Media

Thunderstorm Wind in CLAY, NEBRASKA
From 14-AUG-20 17:15:00 to 14-AUG-20 17:15:00 (CST-6)
Location: CLAY CENTER
Magnitude: 52.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: COOP Observer

Wind gusts were estimated to be near 60 MPH.

Hail in NUCKOLLS, NEBRASKA
From 14-AUG-20 18:30:00 to 14-AUG-20 18:30:00 (CST-6)
Location: SUPERIOR
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Broadcast Media

Tornado in HAMILTON, NEBRASKA
From 14-AUG-20 16:34:00 to 14-AUG-20 16:36:00 (CST-6)
Location: STOCKHAM
Tornado F-scale: EF0
Property damage: 30.00K
Crop damage: 40.00K
Reported by: NWS Storm Survey

Crop damage and scouring occurred. The tornado started in Hamilton County and continued into Clay County.

Tornado in CLAY, NEBRASKA
From 14-AUG-20 16:53:00 to 14-AUG-20 16:54:00 (CST-6)
Location: SARONVILLE
Tornado F-scale: EF0
Property damage: 0.00K
Crop damage: 0.00K
Reported by: NWS Storm Survey

A second brief tornado over Clay County was confirmed through video and was located about 1.5 miles southeast of Saronville. This tornado lasted no more than a minute and there was no reported damage.

Hail in CLAY, NEBRASKA
From 14-AUG-20 16:50:00 to 14-AUG-20 16:52:00 (CST-6)
Location: SUTTON
Magnitude: 2.75 
Property damage: 1.00M
Crop damage: 3.00M
Reported by: Trained Spotter

Hail ranging in size from half dollars to baseballs was reported in Sutton.