During mainly an 18-hour period from the late morning of Wednesday the 24th into the pre-dawn hours of Thursday the 25th, two separate rounds of rain (the first one being the heaviest/most significant) affected nearly this entire six-county North Central Kansas area. While most places tallied only 0.50-1.50 in total, a rather narrow, southwest-northeast swath centered through western/northern Osborne County into far southwestern Jewell County picked up higher amounts into the 2.00-3.50 range, resulting in both short-term areal flooding and also minor flooding along the South Fork Solomon River from near Alton downstream through the Osborne area. Officially, 18-24 hour rainfall totals featured 3.21 at a Kansas Mesonet site on the north side of Osborne and 2.95 at an Osborne CoCoRaHS station. This was almost entirely a heavy rain event, with only one report of nickel size hail between Osborne and Downs shortly before 1 p.m. CDT.
The first round of rain (round 1) was by far the most significant and occurred mainly between the mid-morning and early afternoon hours. A slow-moving multicell storm cluster initially flared up over western Osborne County between 11 a.m. and noon CDT, then drifted through northern Osborne County into Jewell County before weakening and eventually departing the local area between 2-3 p.m. CDT. This round 1 dumped generally 1.50 to 3 over the heart of this swath, including 2.50 at the Kansas Mesonet site in Osborne (1.77 of which fell in 45 minutes) and an unofficial public report of 3.5 south of Alton. As a result, fairly significant short term flooding (including street flooding) ensued during the early afternoon. While most of this initial flooding abated within a few hours, enough runoff eventually drained into the South Fork Solomon River to push the automated gauge at Osborne above its minor flood stage of 14 feet by 7 p.m. CDT. Although not as impactful as round 1, another batch of light to moderate rain blossomed across nearly all of North Central Kansas mainly between 1-6 a.m. CDT on the 25th, leaving behind another widespread 0.50-1.00, including 0.70 at the Kansas Mesonet site in Osborne. If nothing else, round 2 kept the South Fork Solomon River above flood stage a bit longer, as the Osborne gauge crested at 15.8 feet (1.8 ft. above flood stage) at 12:45 a.m. CDT on the 25th but didn't drop below flood stage until 12 hours later.
Briefly looking at the meteorological background of this small-scale flooding event, the Central Plains was under a seasonably-active southwesterly flow regime in the mid-upper levels as a series of low-amplitude disturbances streamed overhead, well to the south of a parent low centered in far south central Canada. At the surface, North Central Kansas was positioned slightly north of a quasi-stationary front stretched across southern and eastern Kansas. Despite seasonably-low mixed-layer CAPE averaging under 1000 J/kg, the combination of fairly strong mid-upper flow and a deep, moist airmass characterized by precipitable water values around 1.5 helped fuel the heavy rain.

Heavy Rain in OSBORNE, KANSAS
From 24-AUG-16 08:00:00 to 25-AUG-16 05:00:00 (CST-6)
Location: OSBORNE
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Approximately four inches of water were rushing over a street in Osborne, as reported by a Kansas Highway Patrol trooper who submitted photos via social media. A Kansas Mesonet gauge in Osborne recorded 1.77 inches between 12:15 p.m. and 1 p.m. CDT...a span of 45 minutes. This mesonet ended up with a 24-hour total of 3.21 as of 6 a.m. CDT on the 25th, but the majority of this fell during the afternoon of the 24th (an additional 0.70 inches fell overnight into the 25th). In addition, a CoCoRaHS station in Osborne reported a 24-hour total of 2.95 as of 7 a.m. CDT on the 25th.

Hail in OSBORNE, KANSAS
From 24-AUG-16 11:53:00 to 24-AUG-16 11:53:00 (CST-6)
Location: DOWNS
Magnitude: 0.88 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Heavy rain also occurred along with the nickel size hail.

Flood in OSBORNE, KANSAS
From 24-AUG-16 17:39:00 to 25-AUG-16 11:38:00 (CST-6)
Location: OSBORNE
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: River/Stream Gage

The river gage at Osborne along the South Fork Solomon River reported a minor flood, lasting from 6:39 p.m. CDT on August 24th to 12:38 p.m. CDT on August 25th. The river peaked at 15.84 feet at 12:45 a.m. CDT on August 25th. Flood stage is 14 feet.