EF1 tornado, Arborville, Nebraska, August 6, 2018

1. EF065 to 85 mph

   Light damage. Surface peeled off some roofs, gutters and siding damaged, branches broken, shallow-rooted trees pushed over.

2. EF186 to 110 mphthis tornado

   Moderate damage. Roofs badly stripped, mobile homes overturned or badly damaged, exterior doors lost, windows broken.

3. EF2111 to 135 mph

   Considerable damage. Roofs torn off well-built houses, frame homes shifted on their foundations, mobile homes destroyed, large trees snapped or uprooted, cars lifted off the ground.

4. EF3136 to 165 mph

   Severe damage. Whole stories of well-built houses destroyed, large buildings badly damaged, trains overturned, trees debarked, heavy cars lifted and thrown.

5. EF4166 to 200 mph

   Devastating damage. Well-built houses leveled, structures with weak foundations moved some distance, cars thrown and large missiles generated.

6. EF5over 200 mph

   Incredible damage. Strong frame houses swept off their foundations, car-sized missiles thrown more than 100 meters, steel-reinforced concrete badly damaged, high-rise buildings deformed.

7. Unrated

   The survey recorded a tornado but could not put a number on it, most often because it crossed open country and damaged nothing a rating can be read from.

Rating

EF1

Date

August 6, 2018

Touchdown

7:43 PM CDT (00:43 UTC)

Lifted

7:47 PM CDT (00:47 UTC)

On the ground

4 minutes

Path length

1.6 miles (2.6 km)

Path width

125 yards (114 m)

Deaths

0

Injuries

0

Property damage

$25,000

Crop damage

$1,000,000

County

York County

Touchdown point

40.993, -97.770

Lift-off point

40.984, -97.742

Record number

1808061843-01

20 damage points were recorded along this path by NWS GID, in the Damage Assessment Toolkit the survey teams carry. The strongest indicator was rated EF1. The highest wind the damage implies is 90 mph.

• 2 grain bins. blown southeast
• Two grains bins blown with the wind.
• End boom of pivot overturned. Grain bin blown in from northwest.
• End Boom overturned on pivot. Grain blown from upstream.

Survey points are preliminary and are the raw material the published rating was built from. Source: NWS Damage Assessment Toolkit.

This Monday evening got somewhat more active than anticipated, as a pair of supercell storms affected mainly the northeast quadrant of South Central Nebraska, resulting in several reports of large hail (up to 2 diameter), damaging winds (up to around 75 MPH), and even one EF-1 tornado. This tornado (spawned by the eastern supercell) touched down in northwestern York County around 7:45 p.m. CDT and tracked east-southeast for less than 2 miles, causing minor damage to a home while also damaging several grain bins and snapping a few large trees. The largest hail reports (2) originated from the Bradshaw and Alda areas. In addition, golf ball size hail occurred near Benedict and Waco, and much of the city of York saw a few minutes of hail to at least half dollar size. As for thunderstorm winds, the highest measured gust was 60 MPH at the York airport. However, especially the eastern supercell produced a concentrated swath of damaging winds, estimated to around 75 MPH in some places. Crop damage (from a combo of both hail/wind) was extensive along this storm's track from central Merrick County into northeastern Hamilton County and northwestern-through-east-central York County. ||Taking a closer look at event evolution/timing, a smattering of weak, elevated storms got underway as early as early-mid afternoon across various parts of the 24-county area, producing little more than brief downpours and small hail. By late afternoon, another round of fairly weak storms flared up within counties mainly north of Interstate 80. However, between 6:30-8:30 p.m. CDT, the situation escalated as one of these initially-weak storms rapidly became severe over Howard County, becoming a legitimate supercell as it tracked east-southeast through parts of Merrick-northeastern Hamilton and York counties. This storm yielded the majority of local severe weather reports/damage (including the York County tornado), before exiting into eastern Nebraska shortly after 8:30 p.m. CDT. Meanwhile, back to the west, another supercell initiated over far northeastern Buffalo County around 8 p.m. CDT. Like its predecessor, it also tracked east-southeast for a few hours, producing large hail in the Alda and Stockham areas before weakening over northern Fillmore County around 10 p.m. CDT. Thereafter, non-severe storms continued percolating well into the night within areas mainly south of Interstate 80 and east of Highway 281, with all of South Central Nebraska finally storm-free by 3 a.m. CDT on the 7th. ||In hindsight, this was actually a decent setup for supercell storm development. However, right up until the early evening hours, locations as far north as Merrick/York counties seemed somewhat unfavorable for higher-end severe potential, especially given that the primary west-east oriented surface front resided well to the south over northern Kansas. However, even in the post-frontal airmass over South Central Nebraska, the combo of afternoon high temperatures into the 80s F and dewpoints in the upper 60s-low 70s F promoted mixed-layer CAPE around 2000 J/kg. This healthy instability, in tandem with seasonably-strong deep-layer wind shear of 40-50 knots and modest forcing provided by a shortwave trough invading from the northwest, proved plenty-sufficient to support a few supercells.

This brief EF-1 tornado occurred in northwest York County, causing damage approximately 7 miles north of Bradshaw. A home was damaged, mainly to soffits and garage doors, and there was also some roof damage. Grain bins were damaged along with several trees. Some larger cedar trees were snapped 2-3 feet above ground. Two irrigation pivots were damaged along the path. Peak winds were estimated to be 90 MPH.||This tornado was associated with a supercell and a much larger scale wind and hail event in the region. There were numerous irrigation pivots overturned or damaged, and crop damage was widespread, especially around and just to the east of the tornado path. Some soybean fields were stripped and beat to the ground, and corn fields were cut down by the wind and hail to only three feet tall in spots.

From NOAA NCEI's Storm Events Database, the narrative the local forecast office wrote for Storm Data.

No tornado warning for this county appears in the archive as in force at the moment the tornado touched down. One was issued for the county at another hour that day.

Every warning and watch covering the touchdown point that day, from the Iowa Environmental Mesonet's archive of National Weather Service products. Lead time is measured from the issue of the warning in force to the touchdown time in the database, both of which were recorded to the minute by different people.

The Storm Prediction Center had this point in a General Thunderstorms Risk. The outlook in force was issued at 19:52 UTC.

SPC's Day 1 convective outlook as it stood when the tornado began, read at the touchdown point. The same archive is on the radar archive.

The radiosonde launches on either side of the tornado, from the nearest station that was launching then, drawn and analyzed the way Storm Lab does: the same diagram, the same parcel and shear definitions SPC's mesoanalysis uses.

The Grand Island radar (KUEX), 94 km away, was scanning. The volume nearest the touchdown began at 00:42 UTC.

Open the radar archive at this moment, over the track

Reflectivity and velocity, decoded from the Level II archive in the browser. Volumes take a few seconds to open the first time.

Local storm reports within 60 km of the path, in the three hours either side.

From the Iowa Environmental Mesonet's archive of National Weather Service local storm reports.

The live radar over the trackEvery 2018 tornado in NebraskaEvery tornado in Nebraska since 1950Warnings in force in Nebraska nowThe forecast where you are

2 more were confirmed in the United States that day.

Ratings are the survey's, read off the damage rather than measured; the rating scale is above. Tornado counts rise through the record as reporting improved, so a year in the 1950s is not comparable with one today except for the strongest tornadoes, which were always noticed.

NOAA Storm Prediction Center tornado database, 1950-2025, the official record kept by NOAA's Storm Prediction Center.