Thunderstorm Wind — Hall, Nebraska

2019-08-07 · near Cairo, Hall, Nebraska

Event narrative

A 69 MPH wind gust was measured by a mesonet station located 1 mile south of Cairo. Wind gusts estimated to be at least 60 MPH were reported in Cairo. Approximately three miles south-southeast of Cairo, near the intersection of Airport Road and Burwick Road, a motorist struck a large tree that had been blown down and died from his injuries.

Wider weather episode

Although its main damage swath was only about 15 miles wide, the narrow-but-intense severe storm complex that raced from northwest-to-southeast through the heart of South Central Nebraska during the pre-dawn hours on this Wednesday was one of the most impactful events of the local convective season. Quite simply, this was a nasty wind storm, packing a punch with gusts ranging from around 60 to nearly 90 MPH along and several miles either side of a line stretching from Ord-Grand Island-Hastings-Hardy. For the city of Grand Island, this was likely the overall-worst wind storm in several years, as the airport ASOS clocked a peak gust of 87 MPH. Countless trees/large branches were blown down within the city, along with several power lines, and there was also some (mainly) minor structural damage. Grand Island Emergency Center logged nearly 300 storm related incidents, including traffic hazards, power outages, alarms and fire concerns from sparking electricity. The storm also caused an (indirect) traffic fatality in rural Hall County southeast of Cairo, when a man crashed his pickup into a large, downed tree arched across a paved county road. To the south in Hastings, damage was less-severe overall, as the ASOS peak gust on the west side of town was only 70 MPH. However, stronger winds likely impacted areas just east of the city, as large trees were uprooted at Central Community College and several rail cars were reportedly blown over at a repair facility near the Clay County line. Several smaller communities also reported notable wind damage, including: Cairo, Alda, Wood River, Doniphan, Glenvil, and Fairfield. West of Clay Center, fairly extensive damage occurred on the U.S. Meat Animal Research Center campus, including broken windows and roof damage to several buildings. In addition to the aforementioned peak wind gusts at Grand Island/Hastings airports, some of the more notable unofficial (mesonet) gusts included: 85 MPH near Fairfield, 80 MPH near Alda and Wood River, 79 MPH in Doniphan and 73 MPH near Nelson. Despite the multitude of damaging wind reports, hail reports were quite scarce, as the vast majority of stones were likely dime size or smaller. Rainfall-wise, a fairly widespread coverage of 2-3 soaked several northern counties including: Valley, Greeley, Sherman, Nance and Merrick. Although resultant flooding was not very extensive in most of the area, the Mira Creek in southern Valley County breached its banks for the second time in five days, again prompting minor flooding on the north side of North Loup that continued into the early morning of the 8th.

Breaking down the timing and meteorological background of this event, it's worth noting that these South Central Nebraska damaging winds were actually the finale to a much longer swath of severe weather that initiated in southern ND and north central SD during the afternoon/evening of the 6th. Between 1-2 a.m. CDT on the 7th, the leading edge of this narrow-but-potent mesoscale convective system (MCS) entered far northern portions of the local area into Valley/Greeley counties, signaling its arrival with a 59 MPH gust at Ord airport. However, the worst was yet to come, as during the next few hours the storm complex morphed into more of an outflow-dominant, high-precipitation supercell, slamming through the Grand Island/Hastings areas between 2:30-3:30 a.m. CDT before eventually exiting Nuckolls/Thayer counties into Kansas by 5 a.m. CDT. In the wake of the main show, a few weaker clusters of storms redeveloped over parts of the area into the daylight hours, but were of little significance. In the big picture of the mid-upper levels, this event occurred within a fairly classic summertime northwest-flow regime, as the Central Plains resided northeast of an expansive ridge centered over New Mexico. At the surface, South Central Nebraska was on the backside of a weak ridge axis centered near the Nebraska-Iowa border. This promoted light-but-steady, south-southeast breezes in advance of the approaching storm complex, with surface dewpoints averaging mid-upper 60s F. Although there were question marks about how far southward into Nebraska the potential severe weather threat would extend, the combination of seasonably-stout flow aloft (deep-layer wind shear of at least 40-60 knots) and sufficient instability (mixed-layer CAPE of 1000-2000 J/kg) was clearly supportive of an intense late-night storm. Also enhancing the severe weather environment was a modest, 30 knot southwesterly low level jet (evident at 850 millibars) and its associated low-level warm air/moisture advection.

View location on OpenStreetMap → (41.0000, -98.6000)

Source: NOAA Storm Events Database, event_id 844340. Narrative written by the NWS forecast office that issued the report.