Hail and Damaging Winds in Nebraska, April 6, 2021

Name: Hail and Damaging Winds in Nebraska, April 6, 2021
Start: 2021-04-06T17:31
End: 2021-04-06T18:58
Location: Nebraska

April 6, 2021 · NWS GID · 6 events in 2 counties and zones

mainly just parts of Dawson and Buffalo counties. Ground-truth reports were fairly limited and primarily consisted of hail, including half dollar size stones in Sumner, quarter size about halfway between Sumner and Overton, and nickel size in Lexington.

Where it happened

Every event with a place to put it. Tap one for its entry below.

Tornadoes
Tropical storms and surge
Floods
Wind
Hail
Winter weather
Heat and drought
Cold
Fire, smoke and dust
Marine and coastal
Other

Open the live radar over this ground

The toll

Deaths: 0
Injuries: 0
Property damage: None recorded
Crop damage: None recorded
Events: 6

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.

What happened

The episode as NWS GID wrote it up.

Despite initial concern for perhaps a more widespread threat, severe storms only impacted a small fraction of South Central Nebraska on this late Tuesday afternoon and evening...mainly just parts of Dawson and Buffalo counties. Ground-truth reports were fairly limited and primarily consisted of hail, including half dollar size stones in Sumner, quarter size about halfway between Sumner and Overton, and nickel size in Lexington. There were also a few marginally-severe wind gusts, including 59 MPH near Eddyville and estimated 60 MPH on the north edge of Kearney, the latter likely caused by an interaction between outflow from nearby storms and gusty north winds along the leading edge of a strong, synoptically-driven cold front. Breaking down event evolution and timing, the first local severe-warned storm of the day fired up over western Dawson County between 5-6 p.m. CDT, quickly becoming undercut by the aforementioned cold front surging in from the northwest. Over the next few hours, another severe storm roamed eastern portions of Dawson County. But already by 8 p.m. CDT the early storms had diminished below severe levels, evolving into a cluster of fairly weak convection (albeit with spotty small hail) that drifted across several counties mainly north of Interstate 80 through mid-late evening. Meanwhile, attempts at robust convective initiation out ahead of the crashing cold front south of Interstate 80/west of Highway 281 largely failed between 6-8 p.m. CDT, yielding only a few showers and weak, brief storms. A bit farther east, a strong storm over north central Kansas tried invading the Nuckolls County area from the south but weakened before doing so. Thus, the vast majority of South Central Nebraska was spared severe convection, as any regional severe activity that developed south of Interstate 80 focused well-south into north central and central Kansas.

On paper, this was a respectable severe weather setup for South Central Nebraska, but ultimately proved to have too many limiting factors for a more widespread event. In the mid-upper levels, lift was provided by a low-amplitude disturbance ejecting across the Central Plains, but the local area remained a bit displaced/east of the strongest forcing associated with a closed low churning across Colorado. At the surface, an effective triple-point took shape over western portions of South Central Nebraska by late afternoon, although the primary low pressure center (around 994 millibars) focused slightly south within western/central Kansas. In addition, moisture return ahead of the cold front into South Central Nebraska was somewhat-modest, with dewpoints only reaching the mid-upper 50s (F). Furthermore, afternoon high temperatures were held down in the 70s in most of the area thanks to fairly widespread clouds, likely enhancing capping and thus hindering pre-frontal, warm sector initiation. Despite the various limiting factors that ultimately contributed to the sparse coverage of severe storms locally, the late afternoon/early-evening mesoscale environment commanded some respect, featuring a narrow axis of mixed-layer CAPE as high as 1500-2000 J/kg in the presence of 30-50 knots of deep-layer wind shear.

What forecasters said that day

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 Apr 6, 5:30 PM CST, 1 minute earlier.

Area forecast discussion, Apr 6, 5:30 PM CST, 1 minute before

AREA FORECAST DISCUSSION
National Weather Service Hastings NE
630 PM CDT Tue Apr 6 2021

.DISCUSSION...(This evening through Tuesday)
Issued at 359 PM CDT Tue Apr 6 2021

Right now the main focus is monitoring conditions over the next few
hours with convection expected to begin to develop along and ahead
of the sfc cold front here shortly. The front has been rather slow
to progress so far today with the triple point generally over far
southwest NE currently (though the dry line is essentially
collocated with the front at this point). Plenty of CU has
developed across the entire area today and has played a role in
keeping things strongly capped so far today. Strong to severe
storms are expected to develop rapidly if the cap breaks...with
around 2,000 j/k of CAPE (mainly over SW portions of the area) and
40-50 kts of effective shear, the main severe threats would be
large hail and damaging winds, but a weak tornado is not out of
the question. While the cap is most likely to break in the western
portions of the area, the eastern areas will have a much harder
time and are likely to stay capped longer and we could see the
severe threat decrease rapidly after midnight tonight. Going
forward, the front looks to continue to slowly inch eastward
overnight bringing gusty winds as well as continuing showers and
thunderstorms.

Behind the front precip chances become more synoptically driven with
light to moderate wraparound precip expected through most of the day
tomorrow. Overall tomorrow is going to be a rather wet and dreary
day with highs expected to only be in the 40s with gusty
northwest winds. Thankfully this won't las too long as conditions
begin to dry out on Thursday and highs rebound back up into the
upper 50s and into the 60s.

To be honest, not a lot of time was spent on the long term
sections of the forecast today. More time was devoted to parsing
out the details of today's anticipated severe weather. The
long term can best be characterized as a series of upper level
waves that moves through and brings more periodic chances for
showers and potentially some thunderstorms. At the upper levels
the current closed low is expected to pass through KS by Thursday
afternoon and deepen as it goes. Behind this current low we will
see brief but collapsing ridging as we enter mainly northwest flow
ahead of the next trof that begins to descend over western MT by
around 00z Friday. As this new trof deepens and pushes eastward, a
new closed low is expected to form Friday afternoon around the
NE,SD,WY border. This low is also expected to deepen as it looks
to swing right through the center of NE by around 00z Saturday.
Then we look to be in something of a "lather, rinse, repeat"
situation where the low migrates east, brief ridging takes over
ahead of another trof descending over MT. While these can appear
to be fairly similar patterns, the devil will be in the details as
usual and confidence in the outer periods is not the greatest
right now.

&&

.AVIATION...(For the 00Z KGRI/KEAR TAFS through 00Z Thursday)
Issued at 610 PM CDT Tue Apr 6 2021

A line of TSRAs is developing to the west and expected to impact
the terminals between 07/01-07/04Z. There will likely be some
gusty winds with the initial passage...gusting 40-45 KTs...along
with the potential for heavy rain...hail and MVFR CIGS. Once this
front/line moves through...CIGS will continue to gradually lower
to IFR levels overnight...with with -SHRAs or VCSHs through much
of the day on Wednesday...along with strong northwesterly winds
gusting to near 40 KTS during the afternoon hours.

&&

.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&

DISCUSSION...Shawkey
AVIATION...Rossi

Hazardous weather outlook, Apr 6, 4:00 PM CST, 1 hour 31 minutes before

Hazardous Weather Outlook
National Weather Service Hastings NE
500 PM CDT Tue Apr 6 2021

KSZ005>007-017>019-NEZ039>041-046>049-060>064-072>077-082>087-
072200-
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-
500 PM CDT Tue Apr 6 2021

This Hazardous Weather Outlook is for south central Nebraska and
portions of north central Kansas.

.DAY ONE...Tonight.

Strong to severe thunderstorms are expected to develop late this
afternoon and track east across the entire forecast area through
the evening hours. The primary hazards will be damaging wind
gusts to near 60 MPH and isolated hail stones up to 2 inches in
diameter, though an isolated tornado is not completely out of the
question...especially across portions of north central Kansas.

.DAYS TWO THROUGH SEVEN...Wednesday through Monday.

During the day on Wednesday, strong northwesterly winds will be
possible across portions of the outlook area, especially west of
Highway 281. Sustained speeds near 30 MPH and gusts near 45 MPH
will be possible.

.SPOTTER INFORMATION STATEMENT...

Spotter activation may be needed through midnight tonight.

&&

More information may be obtained at the following web page:
   https://www.weather.gov/hastings

Rossi

In the hours before

Special weather statement, Apr 6, 4:50 PM CST, 41 minutes before

Special Weather Statement
National Weather Service Hastings NE
550 PM CDT Tue Apr 6 2021

NEZ060-062315-
Dawson NE-
550 PM CDT Tue Apr 6 2021

...SIGNIFICANT WEATHER ADVISORY FOR NORTH CENTRAL DAWSON COUNTY UNTIL
615 PM CDT...

At 550 PM CDT, Doppler radar was tracking strong thunderstorms along
a line extending from 11 miles southwest of Oconto to Cozad. Movement
was north at 30 mph.

Penny size hail and wind gusts up to 50 mph will be possible with
these storms.

Locations impacted include...
Cozad.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

These storms 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.

&&

A Severe Thunderstorm Watch remains in effect until 1100 PM CDT for
south central Nebraska.

LAT...LON 4105 10005 4105 9981 4102 9981 4081 9989
      4082 10001 4104 10005
TIME...MOT...LOC 2250Z 200DEG 25KT 4104 9993 4085 9996

Pfannkuch

Local storm report, Apr 6, 5:23 PM CST, 8 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE HASTINGS NE
623 PM CDT TUE APR 6 2021

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0555 PM     TSTM WND GST     LEXINGTON AIRPORT       40.79N 99.77W
04/06/2021  M51 MPH          DAWSON             NE   AWOS

            51MPH WIND GUST AT THE AIRPORT.

&&

Special weather statement, Apr 6, 5:27 PM CST, 4 minutes before

Special Weather Statement
National Weather Service Hastings NE
627 PM CDT Tue Apr 6 2021

NEZ060-070015-
Dawson NE-
627 PM CDT Tue Apr 6 2021

...SIGNIFICANT WEATHER ADVISORY FOR CENTRAL DAWSON COUNTY UNTIL 715
PM CDT...

At 625 PM CDT, Doppler radar was tracking a line of showers and
fairly weak thunderstorms along a line extending from 7 miles west
of Eddyville to near Lexington. Movement was north at 25 mph.

Despite the weak nature of the storms, storm outflow is combining
with a strong cold front to produce north-northwesterly wind gusts
up to around 50 to 55 MPH.  Pea size hail is also possible.

Locations impacted include...
Lexington and Eddyville.

A Severe Thunderstorm Watch remains in effect until 1100 PM CDT for
south central Nebraska.

LAT...LON 4099 9984 4105 9982 4104 9962 4097 9962
      4073 9972 4074 9988
TIME...MOT...LOC 2325Z 189DEG 20KT 4102 9976 4076 9984

Pfannkuch

Local storm report, Apr 6, 5:29 PM CST, 2 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE HASTINGS NE
629 PM CDT TUE APR 6 2021

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0550 PM     TSTM WND GST     3 WNW LEXINGTON         40.79N 99.79W
04/06/2021  M56 MPH          DAWSON             NE   MESONET

&&

The radar

The Grand Island radar (KUEX), 126 km away, was scanning. The volume nearest the first event began at 23:32 UTC.

Open the radar archive at this moment

Event by event

4 hail, 2 thunderstorm wind. Local standard time, as filed.

Thunderstorm Wind, Dawson

When: April 6, 5:31 PM CST
Where: Dawson County, 2 mi SSW of Eddyville
Measured: 51 kt (59 mph) measured gust
Reported by: Mesonet
Coordinates: 40.993, -99.645

Hail, Dawson

When: April 6, 5:48 PM CST
Where: Dawson County, 1 mi NNW of Lexington
Measured: 0.88 in hail
Reported by: Law Enforcement
Coordinates: 40.793, -99.737

Hail, Dawson

When: April 6, 6:10 PM CST
Where: Dawson County, 8 mi NNW of Overton
Measured: 0.88 in hail
Reported by: Trained Spotter
Coordinates: 40.837, -99.588

Hail, Dawson

When: April 6, 6:15 PM CST to 6:25 PM CST
Where: Dawson County, 8 mi NNW of Overton
Measured: 1 in hail
Reported by: Trained Spotter
Coordinates: 40.837, -99.588

Hail, Dawson

When: April 6, 6:28 PM CST
Where: Dawson County, Sumner
Measured: 1.25 in hail
Reported by: Public
Coordinates: 40.950, -99.520

Thunderstorm Wind, Buffalo

When: April 6, 6:58 PM CST
Where: Buffalo County, 3 mi N of Kearney
Measured: 52 kt (60 mph) estimated gust
Reported by: Emergency Manager
Coordinates: 40.743, -99.080

Wind gusts were estimated to be near 60 MPH, likely due to an interaction between outflow from nearby storms and gusty north winds along the leading edge of a strong cold front.

What these are

Thunderstorm Wind: Winds from a thunderstorm of 50 knots (58 mph) or more, or lower winds that caused damage or casualties. Measured gusts are marked MG, estimated EG.
Hail: Hail three-quarters of an inch or larger, or smaller hail that caused damage, filed with the largest stone measured.

After NWS Directive 10-1605, the rules offices file Storm Data by.

The same day elsewhere

Every storm in Nebraska in 2021 Every state in 2021 This day in weather history Warnings in Nebraska, April 2021

Sources

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: 943110, 943114, 943115, 943117, 943119, 943120.