Although ground-truth reports of severe-criteria hail and wind emanated from only seven counties mainly within northern and central portions of South Central Nebraska on this Friday, the coverage of non-severe thunderstorms and locally heavy rain became rather widespread across much of the area during the late evening and lasting into the early morning hours of the 21st. Despite the somewhat limited areal coverage of verified severe storms, this was a more-significant-than-expected and fairly long-lasting event, as 25 severe thunderstorm warnings were issued in the local area over the course of eight hours between 230-1030 pm CDT, including for a storm that pounded parts of Grand Island with hail up to baseball size.
Several hours prior to the primary severe weather event, a lone morning storm dropped nickel size hail as it passed through Valley and Greeley counties. During the early stages of the main afternoon/evening development, generally between 230-500 pm CDT, transient clusters of strong to marginally severe multicell storms affected areas north of Highway 92, producing ping pong ball size hail near Cotesfield. The next few hours featured the storms of the day as a pair of very slow-moving supercells pounded the northern Hall and southern Howard county area. For the city of Grand Island, the first of these storms likely resulted in the most significant severe event of the 2014 convective season, as a swath extending from a few miles northwest of the city to near the downtown area was drilled with hail stones ranging from quarter to baseball size between mainly 6-7 pm CDT. During this same time frame, a separate, smaller severe storm in Sherman County dropped very large hail up to 3 in diameter in the Rockville area. As the initial Grand Island supercell started dissipating, a second supercell flared up just to its west over northwestern Hall County mainly between 730-830 pm CDT, pounding the Cairo area with hail up to golf ball size for several minutes. While this second supercell started to weaken, a considerable flare-up of strong to severe multicell convection commenced between 730-900 pm CDT within several northern and western counties such as Sherman, Dawson, Gosper and Furnas, resulting in a few reports of estimated 60-65 MPH winds. Generally between 9-11 pm CDT, much of this widespread convection rapidly congealed into a southeast-surging quasi-linear complex that took aim on the Tri-Cities area. During this time, measured wind gusts in Hall County included 58 MPH at the Grand Island airport and 76 MPH at a home weather station near Wood River. These damaging gusts then barreled into Adams County where Hastings airport measured a 67 MPH gust, resulting in the second round of tree damage and fairly minor structural damage within the city in less than one week's time. Beyond 11 pm CDT, there were no further reports of severe storms within South Central Nebraska, although widespread redevelopment of convection continued through the night, especially near the Interstate 80 and Highway 6 corridors. By the end of the night, most of the 24-county area had tallied anywhere from 0.50 to 2 of rain. However, much higher pockets of at least 3-4 of rain targeted primarily northern Hall and southern Howard counties, northern Adams County and central/western Clay County. A few of the highest storm totals from a combination of automated gauges, NWS cooperative observers and NeRAIN observers included 4.07 five miles west-southwest of Clay Center, 3.31 at Hastings airport and 3.11 three miles east-southeast of Dannebrog. Not surprisingly, short-term flooding issues materialized. While rain was still falling during the evening, water was reported over several county roads in southwestern Howard County, along with Highway 11 near Dannebrog. After daybreak on the 21st, reports arrived of several county roads in northwestern Adams County covered in water.
In the big picture of the mid-upper levels, this was not really a synoptically-evident severe weather setup, thanks largely to the lack of a notable mid-upper level disturbance and also seasonably-weak deep layer wind shear. As a result, the severity/longevity of this event was largely underestimated in official forecasts, even within 12 hours of its onset. In the mid levels, fairly weak quasi-zonal flow containing very subtle disturbances was in place over Nebraska, well to the south of a compact-but-strong closed low churning over Saskatchewan and Manitoba. At the surface, only a few subtle boundaries were present within the region, but no well-defined fronts. However, as afternoon temperatures rose well into the upper 80s-low 90s F in the presence of dewpoints in the mid-upper 60s, significant instability developed in the form of mixed-layer CAPE soaring to between 3000-4000 J/kg. Despite 0-6 kilometer deep layer shear averaging no more than 20-30 knots, this highly unstable environment supported robust convection, including the few slow-moving supercells. After dark, the briefly-severe squall line and subsequent multi-hour period of regenerative non-severe storms was aided by the exit region of a 30-40 knot low level jet centered over western KS.

Hail in BUFFALO, NEBRASKA
From 20-JUN-14 21:28:00 to 20-JUN-14 21:28:00 (CST-6)
Location: SHELTON
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Storm Chaser

Heavy Rain in CLAY, NEBRASKA
From 20-JUN-14 22:00:00 to 21-JUN-14 05:31:00 (CST-6)
Location: CLAY CENTER
Property damage: 0.00K
Crop damage: 0.00K
Reported by: COOP Observer

A 24-hour rainfall total of 3.25 inches fell in Clay Center. The rain occurred from late evening into the overnight hours.

Hail in HOWARD, NEBRASKA
From 20-JUN-14 16:35:00 to 20-JUN-14 16:35:00 (CST-6)
Location: DANNEBROG
Magnitude: 0.88 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Hail in VALLEY, NEBRASKA
From 20-JUN-14 09:46:00 to 20-JUN-14 09:46:00 (CST-6)
Location: ARCADIA
Magnitude: 0.88 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Hail in GREELEY, NEBRASKA
From 20-JUN-14 10:47:00 to 20-JUN-14 10:47:00 (CST-6)
Location: SPALDING
Magnitude: 0.88 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Dime to nickel size hail was reported.

Thunderstorm Wind in HOWARD, NEBRASKA
From 20-JUN-14 20:45:00 to 20-JUN-14 20:45:00 (CST-6)
Location: BOELUS
Magnitude: 52.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

A thunderstorm wind gust was estimated at 60 mph.

Thunderstorm Wind in ADAMS, NEBRASKA
From 20-JUN-14 21:01:00 to 20-JUN-14 21:01:00 (CST-6)
Location: PROSSER
Magnitude: 62.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

A thunderstorm wind gust was measured at 71 mph. This gust occurred from outflow well south of the associated thunderstorm.

Thunderstorm Wind in HALL, NEBRASKA
From 20-JUN-14 21:06:00 to 20-JUN-14 21:06:00 (CST-6)
Location: ROSEDALE
Magnitude: 52.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

A thunderstorm wind gust was estimated at 60 mph.

Thunderstorm Wind in HALL, NEBRASKA
From 20-JUN-14 21:11:00 to 20-JUN-14 21:11:00 (CST-6)
Location: (GRI)GRAND IS RGNL A
Magnitude: 50.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: ASOS

A thunderstorm wind gust was measured at 58 mph.

Thunderstorm Wind in ADAMS, NEBRASKA
From 20-JUN-14 21:39:00 to 20-JUN-14 21:39:00 (CST-6)
Location: HASTINGS
Magnitude: 61.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: NWS Employee

This wind gust occurred at the National Weather Service north of Hastings within outflow, well south of the associated thunderstorms, and was at least 70 mph. This gust speed was later confirmed by an anemometer at the National Weather Office.

Thunderstorm Wind in ADAMS, NEBRASKA
From 20-JUN-14 21:52:00 to 20-JUN-14 21:52:00 (CST-6)
Location: HASTINGS
Magnitude: 50.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

A thunderstorm wind gust was measured at 58 mph.

Heavy Rain in ADAMS, NEBRASKA
From 20-JUN-14 21:00:00 to 21-JUN-14 05:00:00 (CST-6)
Location: JUNIATA
Property damage: 0.00K
Crop damage: 0.00K
Reported by: CoCoRaHS

A 24 hour rain total of 3.60 inches fell one mile east northeast of Juniata. The rain occurred during the late evening into the overnight hours.

Heavy Rain in ADAMS, NEBRASKA
From 20-JUN-14 21:00:00 to 21-JUN-14 06:00:00 (CST-6)
Location: (HSI)HASTINGS ARPT
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Official NWS Observations

A 24 hour rainfall total of 3.20 inches occurred at the NWS Hastings office north of town. The rain occurred from late evening into the overnight hours.

Hail in GREELEY, NEBRASKA
From 20-JUN-14 14:05:00 to 20-JUN-14 14:05:00 (CST-6)
Location: GREELEY
Magnitude: 0.88 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Hail in HOWARD, NEBRASKA
From 20-JUN-14 16:40:00 to 20-JUN-14 16:40:00 (CST-6)
Location: DANNEBROG
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Hail in HALL, NEBRASKA
From 20-JUN-14 17:02:00 to 20-JUN-14 17:02:00 (CST-6)
Location: CAIRO
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Nickel to quarter size hail fell.

Hail in HOWARD, NEBRASKA
From 20-JUN-14 20:09:00 to 20-JUN-14 20:09:00 (CST-6)
Location: DANNEBROG
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: 911 Call Center

Thunderstorm Wind in FURNAS, NEBRASKA
From 20-JUN-14 19:24:00 to 20-JUN-14 19:24:00 (CST-6)
Location: CAMBRIDGE
Magnitude: 52.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

A thunderstorm wind gust was estimated to be 60 mph.

Thunderstorm Wind in SHERMAN, NEBRASKA
From 20-JUN-14 19:43:00 to 20-JUN-14 19:43:00 (CST-6)
Location: LITCHFIELD
Magnitude: 52.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

A thunderstorm wind gust was estimated at 60 mph.

Heavy Rain in CLAY, NEBRASKA
From 20-JUN-14 22:00:00 to 21-JUN-14 06:00:00 (CST-6)
Location: CLAY CENTER
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

A 24 hour rain total of 3.70 inches occurred 2 miles west of Clay Center. This was an NERAIN report. The rain occurred from late evening into the overnight hours.

Heavy Rain in ADAMS, NEBRASKA
From 20-JUN-14 21:00:00 to 21-JUN-14 06:00:00 (CST-6)
Location: (HSI)HASTINGS ARPT
Property damage: 0.00K
Crop damage: 0.00K
Reported by: ASOS

A 24 hour total rainfall of 3.31 inches fell at Hastings Municipal Airport. The rain occurred from late evening into the overnight hours.

Heavy Rain in HOWARD, NEBRASKA
From 20-JUN-14 16:00:00 to 21-JUN-14 06:00:00 (CST-6)
Location: DANNEBROG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

A 24 hour total of 3.11 inches of rain occurred 3 miles east southeast of Dannebrog. This report was from an NERAIN observer. The rain occurred from late afternoon into the overnight hours.

Heavy Rain in CLAY, NEBRASKA
From 20-JUN-14 22:00:00 to 21-JUN-14 06:00:00 (CST-6)
Location: CLAY CENTER
Property damage: 25.00K
Crop damage: 0.00K
Reported by: Public

A 24 hour rainfall total of 4.07 inches fell 4 miles west southwest of Clay Center. This was an NERAIN report. The rain occurred from late evening into the overnight hours.

Hail in SHERMAN, NEBRASKA
From 20-JUN-14 17:27:00 to 20-JUN-14 17:38:00 (CST-6)
Location: ROCKVILLE
Magnitude: 3.00 
Property damage: 100.00K
Crop damage: 5.00M
Reported by: Trained Spotter

Hail ranging in size from quarters to tea cups was reported 2 miles northwest of Rockville.

Hail in HOWARD, NEBRASKA
From 20-JUN-14 15:03:00 to 20-JUN-14 15:03:00 (CST-6)
Location: COTESFIELD
Magnitude: 1.50 
Property damage: 25.00K
Crop damage: 1.00M
Reported by: Law Enforcement

Hail in HALL, NEBRASKA
From 20-JUN-14 17:09:00 to 20-JUN-14 17:14:00 (CST-6)
Location: GRAND IS
Magnitude: 2.00 
Property damage: 50.00K
Crop damage: 1.00M
Reported by: Public

Hail ranging in size from ping pong balls to hen eggs was reported northwest of Grand Island.

Hail in HALL, NEBRASKA
From 20-JUN-14 17:40:00 to 20-JUN-14 18:10:00 (CST-6)
Location: GRAND IS
Magnitude: 2.75 
Property damage: 3.00M
Crop damage: 0.00K
Reported by: Trained Spotter

Primarily northern and central portions of the city of Grand Island were pounded by hail ranging in size from quarters to baseballs for approximately 30 minutes.

Hail in HALL, NEBRASKA
From 20-JUN-14 18:51:00 to 20-JUN-14 19:06:00 (CST-6)
Location: CAIRO
Magnitude: 1.75 
Property damage: 100.00K
Crop damage: 2.00M
Reported by: Public

Hail up to Golf Ball size was falling off and on for 15 minutes.

Thunderstorm Wind in GOSPER, NEBRASKA
From 20-JUN-14 19:50:00 to 20-JUN-14 19:50:00 (CST-6)
Location: ELWOOD
Magnitude: 56.00 EG
Property damage: 5.00K
Crop damage: 0.00K
Reported by: COOP Observer

Strong winds estimated to around 65 MPH damaged a large tree.

Thunderstorm Wind in HALL, NEBRASKA
From 20-JUN-14 20:46:00 to 20-JUN-14 20:46:00 (CST-6)
Location: WOOD RIVER
Magnitude: 66.00 MG
Property damage: 35.00K
Crop damage: 0.00K
Reported by: Mesonet

A thunderstorm wind gust was measured at 76 mph.

Thunderstorm Wind in ADAMS, NEBRASKA
From 20-JUN-14 21:43:00 to 20-JUN-14 21:43:00 (CST-6)
Location: (HSI)HASTINGS ARPT
Magnitude: 58.00 MG
Property damage: 35.00K
Crop damage: 0.00K
Reported by: ASOS

A northwest wind gust of 67 mph was measured by the Hastings Airport ASOS. This occurred at the leading edge of the actual thunderstorm. A street light was knocked down in Hastings near the intersection of 7th and Hewett streets.

Flood in ADAMS, NEBRASKA
From 21-JUN-14 04:00:00 to 21-JUN-14 11:00:00 (CST-6)
Location: HAYLAND
Flood cause: Heavy Rain
Property damage: 50.00K
Crop damage: 0.00K
Reported by: Public

Several county roads were covered with water, including an area 6 to 7 miles north of Juniata, in the Thirty-two Mile Creek Basin.

Flood in HOWARD, NEBRASKA
From 20-JUN-14 22:00:00 to 21-JUN-14 11:00:00 (CST-6)
Location: DANNEBROG
Flood cause: Heavy Rain
Property damage: 50.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Water was over Highway 11 south of Dannebrog. Law enforcement barricaded Highway 11 one mile south of mile marker 31 due to flooding. Several county roads were under water in southwestern Howard County. At least four inches of rain fell in the community of Boelus.

Hail in HALL, NEBRASKA
From 20-JUN-14 17:42:00 to 20-JUN-14 17:42:00 (CST-6)
Location: GRAND IS
Magnitude: 1.25 
Property damage: 25.00K
Crop damage: 2.00M
Reported by: Trained Spotter

Half dollar size hail was reported approximately 7 miles north of Grand Island.