Thunderstorm Wind in Kearney County, Nebraska

Wind gusts peaked around 100 MPH along this path, with the most significant damage occurring approximately one mile east of Minden to two miles north-northeast of Minden. Numerous irrigation pivots were flipped and large tree limbs were downed. Along with multiple power poles being snapped, three large metal transmission towers were also downed. A metal outbuilding lost a portion of its roof. Significant crop damage was reported in this whole area.

This Monday afternoon-evening featured the third consecutive day of severe thunderstorms within South Central Nebraska, this time highlighted by a few intense supercells that rolled southeastward through primarily central portions of the area, leaving behind fairly narrow (but in places significant) swaths of damaging winds and/or large hail. The first supercell of the day to invade the local area actually barely brushed its northeast edges, dropping out of northeast Nebraska and skirting eastern/northern portions of Nance, Merrick and Polk counties mainly 3:15-4:15 p.m. CDT before weakening. Although radar signatures and reports from just outside this coverage area suggested that larger hail likely occurred within a small part of South Central Nebraska (especially eastern Nance), the only ground-truth consisted of nickel size stones in Genoa. Following this early activity, a lull of a few hours ensued before the day's main event got underway, consisting of a closely knit pair of twin supercells (precipitation cores separated by no more than 10-15 miles) that marched in step through primarily the following counties between 7-9:30 p.m. CDT: northeastern Dawson, much of Buffalo, northeastern Phelps, much of Kearney, northern/eastern Franklin and western Webster (the separate storm cores eventually merged southeast of Minden). As for wind impacts along this corridor, a few of the most notable reports featured: estimated 100 MPH winds in the Minden area that took down three large metal transmission towers; a mesonet-measured gust of 79 MPH near Axtell and a garage destroyed in town; estimated 70 MPH gusts in the Elm Creek, Kearney and Campbell areas (Kearney Regional Airport AWOS peaked at 61 MPH). All along the aforementioned corridor, there were many instances of flipped irrigation pivots, broken power poles and damaged crops. Hail reports were limited during this main event, but size tended to prevail on the smaller to marginally-severe spectrum, including quarter size stones in Sumner, Odessa and Axtell. About an hour after this initial supercell cluster departed Webster County into Kansas, another large supercell took aim into eastern Dawson/western Buffalo counties from the northwest between 10:30-11:30 p.m. CDT, following a remarkably similar path as the earlier storms and yielding reports of quarter to golf ball size hail in the Eddyville and Miller area before weakening while approaching Interstate 80. A bit later this storm reintensified to radar-indicated severe levels in the Blue Hill area, but there were no verifying reports before it weakened for good over Nuckolls County by 1:30 a.m. CDT, ending the severe storm threat for the night. Outside of the aforementioned supercells, the only other South Central Nebraska severe weather report was a rogue 59 MPH wind gust in Edison, associated with the north end of an overall-weak convective complex that brushed through Furnas, Harlan and Franklin counties from the west between 9-11 p.m. CDT.

Turning to the meteorological background, all supercells that impacted South Central Nebraska initiated at least slightly, if not significantly off to the north-northwest before infiltrating the local area. In fact, the later-evening supercell that entered Dawson/Buffalo counties around 10:30 p.m. CDT developed and first became severe-warned some eight hours prior and 320 miles away...over Weston County, WY! Clearly, the mesoscale environment was quite supportive of long-lived supercells. From a big picture perspective, the basic mid-upper level situation over Nebraska had changed little versus the previous few days, continuing to feature persistent west-northwest flow. However, the big difference on the 6th was that this upper flow became noticeably stronger (aided by the arrival of a pronounced jet streak evident at 300 millibars). As a result, deep layer wind shear ramped up to as high as 50-60 knots. This strong shear profile more than compensated for seasonably-modest instability levels, with evening mixed-layer CAPE over South Central Nebraska only averaging 1000-1500 J/kg. At the surface, there were no features of note, only a weak frontal zone stretched across Nebraska in generally west-northwest to east-southeast fashion.