EF1 tornado, Stockville to Buffalo, Nebraska, May 17, 2019

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

May 17, 2019

Touchdown

7:15 PM CDT (00:15 UTC)

Lifted

7:33 PM CDT (00:33 UTC)

On the ground

18 minutes

Path length

4.7 miles (7.5 km)

Path width

400 yards (366 m)

Deaths

0

Injuries

0

Property damage

$250,000

Counties

Frontier and Dawson counties

Touchdown point

40.699, -100.197

Lift-off point

40.760, -100.159

Record number

1905171815-01

37 damage points were recorded along this path by NWS GID and NWS LBF, in the Damage Assessment Toolkit the survey teams carry. The strongest indicator was rated EF3. The highest wind the damage implies is 157 mph.

• Uprooted tree on county line
• Winds damaged. Shingle loss. Small outbuilding destroyed.
• Slider garage. Moved about 3-4 feet.
• Some roof panel loss on outbuilding. Small old grain bin damages

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

A strong upper level trough of low pressure lifted across the central Rockies during the late afternoon of May 17th. As this feature approached a stalled out frontal boundary, which was anchored along the Kansas and Nebraska border, thunderstorms developed and quickly became severe as they lifted north. A lone supercell produced multiple tornadoes while moving northeast through Frontier County. Two farms sustained damage with the Johnson's farm sustaining damage to every building with the tornado rated an EF-3. As storms moved northeast large hail and damaging winds were reported.

A long-lived supercell produced 3 weak tornadoes over Dawson county on this Friday evening. Around 2 PM CST, a north-northwest to south-southeast broken line of showers and thunderstorms developed from near Lexington to Alma and into north central Kansas. Between 2 and 430 PM CST, this line moved northeast across south central Nebraska. The strongest storms developed over Gosper and Dawson counties and moved north-northeast across Sherman and Valley counties. These storms produced some low-end severe hail (nickel to quarter size) over eastern Dawson and western Buffalo counties, and downburst winds were strong enough to knock a tree onto a lean-to south of Ord. Storms in the rest of the line rapidly weakened. Meanwhile, a lone supercell had formed over northwest Kansas. This storm moved north-northeast and crossed western Dawson county between 545 and 745 PM CST, producing three tornadoes. Two tornadoes had a maximum damage intensity of EF-1. These tornadoes were near Farnam and Cozad. The third tornado was an EF-0 west of Eddyville. The Cozad tornado was the longest with a 10-mile path. This supercell also produced severe hail from Farnam north to Gothenburg, the largest of which was the size of tennis balls in Farnam.||This was a much-anticipated day for storm chasers as the setup was classic. Deepening low pressure was over northeast Colorado, and by 6 PM CST, the pressure was down to 990 mb. This low was located along a stationary front that extended east-northeast across Nebraska. A dryline extended south from the low and a cold front was approaching from the west. The area was in the warm sector with the triple point over southwest Nebraska. As the evening progressed, the low and cold front moved into central Nebraska, with the front merging with the dryline. The flow aloft was moderately-amplified with a low over Utah, embedded within a longwave trough over the West, while a ridge was over the eastern United States. In the wake of the earlier showers and storms, within the inflow of the supercell, temperatures were in the middle 70s, with dewpoints in the middle 60s. With mid-level lapse rates 7.5-8.0 C/km, this resulted in MLCAPE around 3000 J/kg. Deep layer shear was around 40 kt. Low-level winds were strong and veered significantly with height, resulting in 0-1 km SRH between 250 and 300 m2/s2. The Supercell Composite Parameter was about 18 and the Significant Tornado Parameter was around 4.

Tornado briefly touched down in an open field just northwest of Stockville. No damage occurred.

Several 1400 pound hay bales were rolled into two fence lines damaging numerous posts.

Tornado rolled numerous hay bales across a road and into ditches. Twelve power poles were also snapped.

Tornado briefly touched down twisting a large cedar tree and broke large tree limbs.

Tornado touched down in Frontier County, then moved northeast into Dawson County. In Frontier County the tornado downed large tree limbs.

This tornado uprooted some trees, caused minor damage to some homes and completely destroyed at least one storage building. The tornado crossed Highway 23 east of Farnam, then Highway 47 northeast of Farnam before dissipating. The path became indiscernible as the storm approached rougher terrain and the road network was not viable for surveying. The estimated maximum wind speed was 100 MPH.

This tornado was witnessed by many as it formed on the east side of Cozad, where some tree damage and power poles were broken. The nearly 10-mile path weaved to the northeast across a rural landscape. One-half of a large farm machinery shed was complete destroyed and several irrigation pivots were upset, helping delineate the path. Grain bins were destroyed and tree damage was sporadic along the path. The tornado was reported to be rain-wrapped at times. The path become indiscernible as the tornado moved into the hills north of Cozad and the road network became more sparse. The estimated maximum wind speed was 100 MPH.

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

34 minutes of warning. NWS LBF issued a tornado warning for this county at 23:41 UTC, 34 minutes before the tornado touched down, in force until 00:30 UTC.

The county was under a tornado watch, issued at 20:01 UTC and running to 03:46 UTC.

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 Enhanced Risk, with a 0.10 chance of a tornado within 25 miles, in the hatched area where significant tornadoes were expected. The outlook in force was issued at 19:56 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.

Lexington (LXN), 35 km from the path, in the two hours either side.

From the Iowa Environmental Mesonet's archive of airport observations.

The North Platte radar (KLNX), 141 km away, was scanning. The volume nearest the touchdown began at 00:11 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 2019 tornado in NebraskaEvery tornado in Nebraska since 1950Warnings in force in Nebraska nowThe forecast where you are

21 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.