| Episode Narrative |
Although the coverage of strong to severe thunderstorms was rather limited within the 24-county area on this Wednesday afternoon and evening, a small but intense, slow-moving supercell dumped quarter to golf ball size on a localized area near the Howard-Hall-Merrick County intersection between 4-5 PM CDT. Most of this hail fell in a swath between St. Libory and a few miles west of Chapman, and an observer a few miles east-northeast of St. Libory also reported a quick 1.82 inches of rain. As rapidly as this storm formed, it had all but dissipated by 530 PM CDT and ended up being the only storm of the day to produce confirmed severe weather in South Central Nebraska. However, between 430 PM and 6 PM CDT, a few other isolated strong storms briefly flared up in Nance, northern Polk and southwest Furnas Counties. Later in the evening, mainly between 9 PM and midnight CDT, another round of strong storms affected primarily Nuckolls, Fillmore and Thayer Counties in southeast portions of the area before exiting into Kansas. In the mid and upper levels the flow was quasi-zonal, with the primary synoptic forcing for this event consisting of subtle shortwave energy passing through the Central Plains along the southern periphery of a dominant upper low centered near the North Dakota-Manitoba border. At the surface, a slow moving cold front gradually passed through South Central Nebraska during the day, with the limited storm development focused on the immediate cool side of the boundary where dewpoints had pooled well into the 60s to near 70F. Around the time of the large hail near St. Libory, the mesoscale environment was quite unstable with around 2000 J/kg mixed-layer CAPE but with only around 30 knots of 0-6 kilometer vertical wind shear. |
