For mainly southeastern portions of South Central Nebraska (mainly southeast of a York-Red Cloud line), this was an active Friday evening and early Saturday morning of thunderstorms. Things started out with a smattering of large hail reports before transitioning to mainly a heavy rain and relatively minor flash flooding event, particularly within western Nuckolls and far eastern Webster counties where rain totals of 2-4 inches were common, and highlighted by 4.72 per an unofficial mesonet west-southwest of Nelson. As for hail, the largest reported stones up to golf ball size occurred in McCool Junction and southeast of Sutton. Severe-criteria wind reports were quite limited, but a mesonet southwest of Nelson gusted to 64 MPH and a completely separate batch of storms farther west yielded a 63 MPH mesonet gust near Cambridge. The most impactful flooding report involved a multiple-hour closure of Highway 136 in far western Nuckolls County due to water over the road. In addition, runoff from heavy rain promoted minor flooding along the Republican River in southern Nuckolls County, with the automated gauge near Hardy cresting at 11.66 ft. during the very early morning hours of Sunday the 16th (flood stage 11.0 ft.).
Breaking down event evolution, severe storms initially got underway between 8-10 p.m. CDT as a cluster of semi-discrete cells erupted within Clay, Fillmore and southern York counties, yielding the majority of the evening's hail reports. Then between 10 p.m. and midnight CDT and slightly to the southwest of the initial storms, additional severe convection and flooding rains blossomed over Nuckolls and eastern Webster counties. After midnight, the most intense storms gradually weakened and/or slipped south of the state line into Kansas, although weaker activity lingered a few more hours before ending altogether. Completely separate from (and several counties to the west of) the severe convection in southeastern counties, a small cluster of storms entered Furnas County from the west shortly before midnight CDT, generating the aforementioned severe gust near Cambridge before quickly weakening. Turning to the meteorological setup, a broad quasi-zonal flow regime was present in the mid-upper levels, featuring passing low-amplitude disturbances. At the surface, the initial evening development seemed to concentrate along a subtle, west-east front, in a mesoscale environment featuring a relatively potent combination of 2000-3000 J/kg mixed-layer CAPE and around 30 knots of deep-layer wind shear. In addition, convection was aided by warm air/moisture advection along the northwestern fringes of a nocturnal low level jet primarily aligned from southern Kansas into Missouri.