EF0 tornado, Porter, Nebraska, June 7, 2010

1. EF065 to 85 mphthis tornado

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

2. EF186 to 110 mph

   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

EF0

Date

June 7, 2010

Touchdown

6:20 PM MDT (00:20 UTC)

Lifted

6:35 PM MDT (00:35 UTC)

On the ground

15 minutes

Path length

0.5 miles (0.8 km)

Path width

100 yards (91 m)

Deaths

0

Injuries

0

County

Sioux County

Touchdown point

42.010, -103.660

Lift-off point

42.010, -103.660

Record number

1006071820-01

5 damage points were recorded along this path by NWS CYS, in the Damage Assessment Toolkit the survey teams carry. The strongest indicator was rated EF1. The highest wind the damage implies is 100 mph.

• Partial roof liftoff on showroom building. Inside ceiling tile damage. Hail damage on most cars in dealership lot an inch to a couple inches in size.
• Broken windows on home on west side. Large tree limbs broken off ranging from 4 inches to 2 feet in diameter. Owners shed/garage mostly destroyed. Roof of shed completely lifted up and blown into trees behind shed. A tree was uprooted.
• Two businesses affected. One large shed had a complete section of roof torn off with a side wall also ripped in that section and adjacent part of building. Debris field could be seen on the farmland downwind of the business for approximately a quarter mile to the John Deere dealership. The roof of the building was reported to be found a mile and a half down the road on US highway 26. At the John Deere dealership, roof of the adjacent business above was blown into the tractors and buildings. Grain bin dented severely and hay wagon tipped on one wheel. Storm appeared to parallel US highway 26.
• An approximately 100 foot long garage and shed was blown over and collapsed on two vehicles located inside the garage. Resident also had two wooden fences blown over in yard but bicycle next to fence was left standing.

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

Moist southerly winds brought 50 to mid 60 degree dew points into the area. Due to so much moisture present, low status formed and lasted through the early afternoon. The stratus caused the atmosphere to remain stable through the early afternoon until the stratus began to clear out. With the moisture still present during the afternoon and a strong jet stream overhead, thunderstorms that former over the higher terrain of Southeast Wyoming began to move eastward into the panhandle. The unstable conditions also allowed thunderstorms to develop in the panhandle during the late afternoon and evening hours.

Spotter saw tornado with debris roughly 10 miles north of Scottsbluff. Storm survey found no damage the next day. Due to no visible signs of tornado from the storm survey had to estimate duration, path width and path length.

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.

The county was under a tornado watch, issued at 21:31 UTC and running to 02:04 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 Slight Risk, with a 0.05 chance of a tornado within 25 miles. The outlook in force was issued at 20:00 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 Cheyenne radar (KCYS), 135 km away, was scanning. The volume nearest the touchdown began at 00:20 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 2010 tornado in NebraskaEvery tornado in Nebraska since 1950Warnings in force in Nebraska nowThe forecast where you are

8 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.