Thunderstorms produced mostly hail along with a little wind damage, and excessive rainfall on this Tuesday afternoon and evening. The first thunderstorms began forming just after 3 pm and were part of a broken line of isolated storms that extended from O'neill south to near Kearney, and then southwest into Kansas. A dominant storm developed along the Hall-Howard County line by 4 p.m.. This storm became severe as it continued east, affecting adjoining portions of Hamilton and Merrick Counties through 5:30 pm CST. Around 4:50 pm CST, this storm produced a gustnado near Chapman, along with hail up to 1.5 inches in diameter, and estimated winds around 70 mph. After 5:30 pm, other storms developed in close-proximity, displaying multicell characteristics. An east-west oriented line segment of storms formed across Hamilton and York Counties. This line remained intact until 8 p.m. CST. Storms within this line trained, producing severe hail up to the size of golf balls and flash flooding from several inches of rain. Outflow winds overturned an irrigation pivot and produced blowing dust that reduced the visibility to near zero near Bradshaw. Several reports of gustnadoes were received along the leading edge of the outflow.
Meanwhile, one storm crossed into Furnas County from Kansas beginning around 4 p.m. CST. Several other thunderstorms developed around it, forming a small mostly sub-severe cluster. The initial storm briefly became severe, producing estimated winds of 85 mph in northern Furnas County. This cluster moved northeast and eventually formed a short line segment that was oriented from northwest to southeast. This line produced winds of 50 to 55 mph in a couple locations in Adams and Clay Counties. It then crossed Hall, Hamilton, and York Counties from 7 to 9 p.m. CST, adding to the already impressive rainfall amounts. Much of northeastern Hamilton County received 4 to 6 inches of rain in less than 6 hours. The highest total was 6.77 inches at Marquette. These high rainfall amounts were surrounded by a larger area of 2 to 3 inches which extended across Hall, Hamilton, and York Counties. This rain resulted in extensive flooding over northeastern Hamilton County and along the Big Blue River in Polk County.
Occluding low pressure was along the Montana-North Dakota border on this day. The triple point was over South Dakota, with a quasi-stationary warm front extending east through the Midwest and Mid-Atlantic States. The cold front was advancing eastward across Nebraska, and was moving through south central Nebraska during the late afternoon and early evening hours. In the upper levels, a broad trough covered much of the Unites States, anchored by an intensifying upper-low over Montana. A closed high was over Ontario, Canada. Temperatures in the pre-storm environment climbed to around 80 degrees, with dewpoints in the middle to upper 50s. Mid-level lapse rates were poor resulting in MLCAPE of not more than 1500 J/kg. Effective deep layer shear was 30 to 35 knots.

Hail in YORK, NEBRASKA
From 10-MAY-16 18:08:00 to 10-MAY-16 18:08:00 (CST-6)
Location: BENEDICT
Magnitude: 0.88 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Hail in MERRICK, NEBRASKA
From 10-MAY-16 17:00:00 to 10-MAY-16 17:00:00 (CST-6)
Location: CHAPMAN
Magnitude: 1.25 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Hail was accompanied by 60 MPH wind gusts.

Hail in HAMILTON, NEBRASKA
From 10-MAY-16 17:05:00 to 10-MAY-16 17:05:00 (CST-6)
Location: MARQUETTE
Magnitude: 1.25 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Social Media

Hail in YORK, NEBRASKA
From 10-MAY-16 18:38:00 to 10-MAY-16 18:38:00 (CST-6)
Location: BRADSHAW
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Hail was accompanied by 60 MPH winds.

Hail in ADAMS, NEBRASKA
From 10-MAY-16 19:12:00 to 10-MAY-16 19:12:00 (CST-6)
Location: KENESAW
Magnitude: 0.88 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Social Media

Hail in YORK, NEBRASKA
From 10-MAY-16 20:00:00 to 10-MAY-16 20:00:00 (CST-6)
Location: BENEDICT
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Hail in CLAY, NEBRASKA
From 10-MAY-16 20:26:00 to 10-MAY-16 20:26:00 (CST-6)
Location: SUTTON
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Hail in FILLMORE, NEBRASKA
From 10-MAY-16 20:44:00 to 10-MAY-16 20:44:00 (CST-6)
Location: SHICKLEY
Magnitude: 0.88 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Heavy Rain in YORK, NEBRASKA
From 10-MAY-16 06:00:00 to 11-MAY-16 06:00:00 (CST-6)
Location: GRESHAM
Property damage: 0.00K
Crop damage: 0.00K
Reported by: COOP Observer

Storm total rainfall report was 3.35 inches.

Heavy Rain in HAMILTON, NEBRASKA
From 10-MAY-16 06:00:00 to 11-MAY-16 06:00:00 (CST-6)
Location: MARQUETTE
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Storm total rainfall report was 6.50 inches.

Heavy Rain in HAMILTON, NEBRASKA
From 10-MAY-16 06:00:00 to 11-MAY-16 06:00:00 (CST-6)
Location: AURORA
Property damage: 0.00K
Crop damage: 0.00K
Reported by: CoCoRaHS

Storm total rainfall report was 4.01 inches.

Heavy Rain in HAMILTON, NEBRASKA
From 10-MAY-16 06:00:00 to 11-MAY-16 06:00:00 (CST-6)
Location: MARQUETTE
Property damage: 0.00K
Crop damage: 0.00K
Reported by: CoCoRaHS

Storm total rainfall report was 6.77 inches.

Heavy Rain in HAMILTON, NEBRASKA
From 10-MAY-16 06:00:00 to 11-MAY-16 06:00:00 (CST-6)
Location: HORDVILLE
Property damage: 0.00K
Crop damage: 0.00K
Reported by: CoCoRaHS

Storm total rainfall report was 4.35 inches.

Heavy Rain in HAMILTON, NEBRASKA
From 10-MAY-16 06:00:00 to 11-MAY-16 06:00:00 (CST-6)
Location: HORDVILLE
Property damage: 0.00K
Crop damage: 0.00K
Reported by: CoCoRaHS

Storm total rainfall report was 4.36 inches.

Hail in HAMILTON, NEBRASKA
From 10-MAY-16 17:41:00 to 10-MAY-16 17:41:00 (CST-6)
Location: HAMPTON
Magnitude: 1.75 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: County Official

Thunderstorm Wind in MERRICK, NEBRASKA
From 10-MAY-16 16:49:00 to 10-MAY-16 17:00:00 (CST-6)
Location: CHAPMAN
Magnitude: 61.00 EG
Property damage: 250.00K
Crop damage: 250.00K
Reported by: Trained Spotter

Wind gusts estimated to be near 70 MPH resulted in some irrigation pivot damage in the area. Wind was accompanied by half dollar size hail.

Thunderstorm Wind in HARLAN, NEBRASKA
From 10-MAY-16 17:25:00 to 10-MAY-16 17:25:00 (CST-6)
Location: OXFORD
Magnitude: 74.00 EG
Property damage: 250.00K
Crop damage: 250.00K
Reported by: County Official

Wind gusts were estimated to be as high as 85 MPH.

Thunderstorm Wind in HAMILTON, NEBRASKA
From 10-MAY-16 18:00:00 to 10-MAY-16 18:00:00 (CST-6)
Location: MARQUETTE
Magnitude: 61.00 EG
Property damage: 250.00K
Crop damage: 250.00K
Reported by: Social Media

Wind gusts estimated to be near 70 MPH resulted in some pivot damage in the area.

Thunderstorm Wind in YORK, NEBRASKA
From 10-MAY-16 18:38:00 to 10-MAY-16 18:38:00 (CST-6)
Location: BRADSHAW
Magnitude: 52.00 EG
Property damage: 15.00K
Crop damage: 250.00K
Reported by: Public

Wind gusts were estimated to be near 60 MPH and were accompanied by quarter size hail.

Flash Flood in HAMILTON, NEBRASKA
From 10-MAY-16 18:10:00 to 11-MAY-16 00:30:00 (CST-6)
Location: MARQUETTE
Flood cause: Heavy Rain
Property damage: 25.00K
Crop damage: 1.00M
Reported by: Emergency Manager

Training, slow moving thunderstorms with torrential rainfall resulted in flash flooding across northern Hamilton, far southwestern Polk and far north-northwestern York Counties. Hamilton County was the hardest hit, with radar estimates of 5 to 8 inches of rain. Numerous county roads were covered with water and were closed. One home near Marquette in Hamilton County had about 2 feet of water inside and around the house. Animals at the farmstead had to be moved, and witnesses claimed the horses were nearly belly-deep in water at one point. This water moved downstream into Polk and York Counties, causing flooding along the Big Blue River.

Flash Flood in POLK, NEBRASKA
From 10-MAY-16 18:10:00 to 11-MAY-16 00:30:00 (CST-6)
Location: POLK
Flood cause: Heavy Rain
Property damage: 75.00K
Crop damage: 3.00M
Reported by: Emergency Manager

Training, slow moving thunderstorms with torrential rainfall resulted in flash flooding across northern Hamilton, far southwestern Polk and far north-northwestern York Counties. Hamilton County was the hardest hit, with radar estimates of 5 to 8 inches of rain. Numerous county roads were covered with water and were closed. One home near Marquette in Hamilton County had about 2 feet of water inside and around the house. Animals at the farmstead had to be moved, and witnesses claimed the horses were nearly belly-deep in water at one point. This water moved downstream into Polk and York Counties, causing flooding along the Big Blue River.

Flash Flood in YORK, NEBRASKA
From 10-MAY-16 18:10:00 to 11-MAY-16 00:30:00 (CST-6)
Location: ARBORVILLE
Flood cause: Heavy Rain
Property damage: 10.00K
Crop damage: 500.00K
Reported by: Emergency Manager

Training, slow moving thunderstorms with torrential rainfall resulted in flash flooding across northern Hamilton, far southwestern Polk and far north-northwestern York Counties. Hamilton County was the hardest hit, with radar estimates of 5 to 8 inches of rain. Numerous county roads were covered with water and were closed. One home near Marquette in Hamilton County had about 2 feet of water inside and around the house. Animals at the farmstead had to be moved, and witnesses claimed the horses were nearly belly-deep in water at one point. This water moved downstream into Polk and York Counties, causing flooding along the Big Blue River.