During the second week of September, an upper-level low pressure system formed and became cut off from the mean flow over the Intermountain West. This low slowly migrated from near Las Vegas north to Idaho. Subtropical high pressure remained stationary over the Southern Plains. This configuration channeled a stream of anomalously high moisture into the Rockies. With surface high pressure essentially stationary over the Northern Plains, several days of easterly upslope flow into the Colorado Rockies resulted in tremendous rainfall and catastrophic flash flooding in and around Boulder, Colorado. The highest amounts occurred on September 11th, 12th and 13th. Widespread multi-day rainfall totals were 7 to as high as 17 inches. In the city of Boulder, all rainfall records were broken for the month of September, for any calendar month and for any year. Northeastern Colorado is the headwaters of the South Platte River. This tremendous volume of water began its journey down the South Platte River, reaching the confluence with the North Platte on Friday, September 20th.
By Saturday the 21st, water reached western Dawson county. River levels rose rapidly and dramatically at Gothenburg and points downstream. Year-to-date precipitation over the North and South Platte River Basins was roughly five inches below normal. So, over much of South Central Nebraska, Platte River levels were  below normal. The water reached Cozad Saturday night and in the following 24 hours, the water level increased from one foot to five feet. The peak crest was around 7 ft Tuesday morning the 24th. The story was similar as the water continued to move downstream, reaching Overton and Kearney Monday night and Grand Island Tuesday. In some areas, prior to the arrival of the flood-generated water, the Platte River was down to a narrow trickle a few inches to a couple feet wide. The flood water filled the breadth of the riverbed and its multiple channels, with standing water occurring in some low-lying areas adjacent to the riverbanks.
At all locations along the river, once water levels reached the crest, they were very slow to recede. While the water levels did not remain at the crest long, they took around three days to drop one foot from the crest height. This was partially due to rain that fell over South Central Nebraska. However, this still indicated the significant volume of water generated from the flooding rains far upstream, and it was especially impressive given that it took little more than a single day for the river levels to rise several feet.

Flood in DAWSON, NEBRASKA
From 23-SEP-13 11:00:00 to 30-SEP-13 06:00:00 (CST-6)
Location: GOTHENBURG
Flood cause: Heavy Rain
Property damage: 50.00K
Crop damage: 1.00M
Reported by: River/Stream Gage

Flood in PHELPS, NEBRASKA
From 24-SEP-13 14:00:00 to 30-SEP-13 23:59:00 (CST-6)
Location: BERTRAND
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: River/Stream Gage

Flood in KEARNEY, NEBRASKA
From 26-SEP-13 14:00:00 to 30-SEP-13 23:59:00 (CST-6)
Location: NEWARK
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: River/Stream Gage

Flood in BUFFALO, NEBRASKA
From 25-SEP-13 02:00:00 to 30-SEP-13 23:59:00 (CST-6)
Location: ELM CREEK
Flood cause: Heavy Rain
Property damage: 10.00K
Crop damage: 0.00K
Reported by: River/Stream Gage

Flood in HALL, NEBRASKA
From 27-SEP-13 05:00:00 to 30-SEP-13 23:59:00 (CST-6)
Location: WOOD RIVER
Flood cause: Heavy Rain
Property damage: 5.00K
Crop damage: 0.00K
Reported by: River/Stream Gage