As severe storm/flooding events go, some are definitely better-anticipated than others (forecast-wise). Unfortunately, what transpired on this Thursday evening the 22nd into early Friday morning the 23rd fell into the low-predictability category, as an apparent mesoscale convective vortex (MCV) sparked isolated-but-intense thunderstorms that not only dumped flooding rains on parts of Sherman/Buffalo/Howard/Hall/Adams counties, but also brought a damaging combination of winds and hail to parts of Hall/Adams counties. Going into more detail, and starting with the severe weather aspect, around 1:30 a.m. CDT a severe thunderstorm rapidly blossomed over southern Hall County. It started drifting slowly south-southeast, reaching Hastings around 3 a.m. CDT and eventually weakening/dissipating over southern Clay County between 4-5 a.m. CDT. Along the way, this storm produced winds measured as high as 76 MPH at Hastings airport, along with copious amounts of hail up to half dollar size. In Hall County, at least one semi truck was blown over on Interstate 80. However, Hastings was the hardest hit local community, specifically the west side of town and adjacent rural areas, where the wind/hail combo shredded trees and gardens, damaged house siding and ravaged maturing crops. Some hail drifts in/near west Hastings were still visible well into the daytime hours (side note: this was at least the third time in 2019 that severe storms impacted Hastings). Flooding was certainly an issue within Hall/Adams counties as well, particularly in the Amick Acres neighborhood west of Doniphan where a CoCoRaHS observer measured 4.54 of rain. This prompted extensive flooding of basements and overflowed a series of small lakes (at least minor flooding would continue at Amick Acres for several more days). Flooding was less-severe in the Hastings area, but there was still short-term flooding of fields and rural roads (including the brief closure of Showboat Road just east of town).
Although the weather impacts in Hall/Adams counties dominated the local news headlines, significant-but-localized flooding also occurred in more rural areas of southern Sherman, northeastern Buffalo and southeastern Howard counties earlier in the night. Focusing on the more significant event in Sherman/Buffalo counties, a slow-moving series of re-generating storms dumped 2-5+ inches of rain along a narrow corridor from south of Loup City to south of Ravenna, with the majority falling between 7 p.m. and midnight CDT. There were a few unofficial public reports of totals as high as 7-7.50, along with some ground-truth reports of flooding/flash flooding, including water running over portions of Highways 10 and 68. As mentioned at the top, the development and intensity of these evening and overnight storms was not well-anticipated in official forecasts, as numerical models failed to latch onto the apparent influence of a pesky, slow-moving MCV that drifted eastward into South Central Nebraska during the day on the 22nd and stuck around through the night. The larger scale mid-upper air pattern over Nebraska was not very notable, featuring only subtle/low amplitude disturbances ejecting eastward from a trough centered over the Northern Rockies. Adding to the surprising intensity of this convection, mesoscale analysis depicted only weak deep-layer wind shear of no more than 25-30 knots, along with only around 1000 J/kg most-unstable CAPE.