Despite weak upper forcing and fairly strong convective inhibition (CINH) keeping the vast majority of South Central Nebraska storm-free on this early Tuesday evening, a pair of rogue, slow-moving supercell storms were able to breach the cap and produce hail to at least golf ball size in small portions of Buffalo and Clay counties. m.
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Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.
The episode as NWS GID wrote it up.
Despite weak upper forcing and fairly strong convective inhibition (CINH) keeping the vast majority of South Central Nebraska storm-free on this early Tuesday evening, a pair of rogue, slow-moving supercell storms were able to breach the cap and produce hail to at least golf ball size in small portions of Buffalo and Clay counties. The far southeastern Buffalo County storm initiated first, shortly before 7 p.m. CDT, and drifted slowly south before rapidly dissipating only about an hour later. Along the way though, it dumped hail up to 2 inches in diameter on Shelton. Just as this storm was fading the second one got going in southeastern Clay County around 8 p.m. CDT and followed a very similar life cycle, drifting slowly south-southeast and dissipating 60-90 minutes later, but not before dropping golf ball size hail north of Edgar that reportedly damaged crops and cracked vehicle windshields. A weaker storm that split eastward from the Clay County supercell briefly affected northwestern Thayer County, but once this convection died around 930 p.m. CDT with the onset of diurnal cooling, the remainder of the night was storm-free.
This somewhat-surprising, albeit brief/localized event was a textbook case of why one can never say never to at least isolated robust convection in a high instability environment during summer peak heating. In the mid-upper levels, South Central Nebraska resided along the northeast periphery of an expansive ridge centered over the Four Corners region. Although deep-layer shear was respectable (around 40 knots), the flow over the Central Plains lacked any notable disturbances and fairly strong capping was present (as indicated by 700 millibar temperatures around 12 C). However, upon closer review, a subtle northwest-southwest oriented surface boundary was draped across the heart of the local area, promoting weak low-level convergence between light easterly breezes and light southerlies. This subtle convergence, in tandem with fairly robust mixed-layer CAPE of 2000-3000 J/kg (owing to temperatures/dewpoints well into the 90s/60s F) proved just sufficient enough to spark the isolated severe activity.
The local office's own words before the first event, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.
NWS Hastings, NE wrote its last area forecast discussion before the first event at Jun 15, 5:36 PM CST, 49 minutes earlier.
AREA FORECAST DISCUSSION National Weather Service Hastings NE 636 PM CDT Tue Jun 15 2021 ...Aviation Update... .DISCUSSION...(This evening through Tuesday) Issued at 323 PM CDT Tue Jun 15 2021 Cirrus from earlier convection continues to thin across the western part of the area this afternoon. A surface high pressure system across the area is keeping the winds light and somewhat variable. The upper level ridge continues across and to the west of the area tonight through Thursday. Temperatures are expected to remain on the warm side. Wednesday a surface low and cold front start to develop to the northwest of the forecast area. This will keep south winds across the area which will increase to 15 to 20 mph. Moisture will increase on the south winds and the higher dew points are expected to increase the heat index values to a few degrees on either side of 100 degrees. By Thursday, the cold front starts to work into the forecast area, but is not as strong and the temperatures are not expected to be much cooler. They will be a bit cooler in the north, but a little warmer in the south. The difference will be that the dew points will be a little lower and the heat index could actually be lower. Thursday night, the front will move to the south of the forecast area and there is an upper level wave that moves over the ridge. Models have a few differences in the location of the weak front and the precipitation that is possible. Have kept some low PoPs for much of the area. Friday through Tuesday the ridge broadens and the flow across the area becomes more zonal. There are a few waves that move through the area and there will be some more thunderstorm activity. At this time, the strongest wave and best chance for thunderstorms appears to be Saturday night. Otherwise, there will be on and off chances for thunderstorms. The models have a few differences, but most of the systems seem to be more during the night-time. && .AVIATION...(For the 00Z KGRI/KEAR TAFS through 00Z Thursday) Issued at 635 PM CDT Tue Jun 15 2021 General overview: Overall, another high-confidence VFR ceiling/visibility forecast, with the main difference being slightly-stronger wind speeds compared to these past 24 hours (especially Wednesday afternoon). Details: Assuming that no isolated/sneaky convection manages to bubble up directly over the area between now and nightfall/roughly 02-03Z, (currently considered no more than a 5-10 percent chance and thus not included in TAFs), this should be another straightforward and dry/storm-free aviation period with minimal mid-high cloud cover at most. As for surface winds, they will average no more than 08-10KT this evening-overnight, generally averaging from a southeasterly direction. However, speeds pick up a touch during the day Wednesday, with sustained southerly speeds around 15KT/gusts around 20KT common, especially 17-23Z. On one last wind-related note: There are hints of weak-ish low level wind shear (LLWS) especially 10-14Z as winds mainly between 500-1,500 ft. increase to 25-30KT from the southwest. However, with overall-shear magnitude looking to only average around 25KT, this looks a bit marginal for formal TAF inclusion. Something for later forecasts to keep an eye on though. && .GID WATCHES/WARNINGS/ADVISORIES... NE...NONE. KS...NONE. && DISCUSSION...JCB AVIATION...Pfannkuch
Hazardous Weather Outlook...UPDATED National Weather Service Hastings NE 725 PM CDT Tue Jun 15 2021 KSZ005>007-017>019-NEZ039>041-046>049-060>064-072>077-082>087- 170030- Phillips-Smith-Jewell-Rooks-Osborne-Mitchell-Valley-Greeley-Nance- Sherman-Howard-Merrick-Polk-Dawson-Buffalo-Hall-Hamilton-York- Gosper-Phelps-Kearney-Adams-Clay-Fillmore-Furnas-Harlan-Franklin- Webster-Nuckolls-Thayer- 725 PM CDT Tue Jun 15 2021 This Hazardous Weather Outlook is for south central Nebraska and portions of north central Kansas. .DAY ONE...This Evening and Tonight. Through around 10 PM, very isolated, spotty thunderstorm activity will be possible within the outlook area, particularly from near the Nebraska Tri Cities southward into north central Kansas. Although coverage will remain very spotty, a strong to briefly- severe storm cannot be ruled out, with quarter size hail and 60 MPH winds the main threats. .DAYS TWO THROUGH SEVEN...Wednesday through Monday. Heat will be even more of a concern Wednesday and Thursday afternoons, as most of the outlook area will likely reach a heat index of 100 to 105 degrees each afternoon. Periodic thunderstorm chances arrive starting Thursday night. At this time, it is still too soon to confidently assess the potential for any severe storms during the next several days. .SPOTTER INFORMATION STATEMENT... Spotters are encouraged to report any hail or strong thunderstorm winds from isolated activity that develops this evening. && More information may be obtained at the following web page: https://www.weather.gov/hastings Pfannkuch
Special Weather Statement National Weather Service Hastings NE 701 PM CDT Tue Jun 15 2021 NEZ061-062-074-075-160030- Buffalo NE-Adams NE-Hall NE-Kearney NE- 701 PM CDT Tue Jun 15 2021 ...SIGNIFICANT WEATHER ADVISORY FOR SOUTHEASTERN BUFFALO AND SOUTHWESTERN HALL COUNTIES UNTIL 730 PM CDT... At 700 PM CDT, Doppler radar was tracking a strong thunderstorm over and just north of Shelton, or 20 miles northeast of Kearney. This storm was nearly stationary, but drifting very slowly outh. Half inch hail and winds in excess of 40 mph will be possible with this storm. Locations impacted include... Shelton. PRECAUTIONARY/PREPAREDNESS ACTIONS... Heavy rainfall is also occurring with this storm, and may lead to brief localized flooding. Do not drive your vehicle through flooded roadways. This storm may intensify, so be certain to monitor local radio stations and available television stations for additional information and possible warnings from the National Weather Service. && LAT...LON 4087 9880 4089 9864 4068 9859 4065 9882 TIME...MOT...LOC 0000Z 344DEG 4KT 4081 9873 Pfannkuch
The Grand Island radar (KUEX), 57 km away, was scanning. The volume nearest the first event began at 00:27 UTC.
2 hail. Local standard time, as filed.
Hail up to 2 inches in diameter was reported.
Hail up to golf ball size caused vehicle and crop damage in the area.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Nebraska in 2021Every state in 2021This day in weather historyWarnings in Nebraska, June 2021
NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-24. Each event’s entry at NCEI: 964011, 964013.