EF1 tornado, Denver to (Den)Denver Intl Arp, Colorado, June 24, 2015

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

June 24, 2015

Touchdown

4:48 PM MDT (22:48 UTC)

Lifted

5:10 PM MDT (23:10 UTC)

On the ground

22 minutes

Path length

2.8 miles (4.5 km)

Path width

50 yards (46 m)

Deaths

0

Injuries

0

County

Denver County

Touchdown point

39.725, -104.904

Lift-off point

39.737, -104.852

Record number

1506241648-01

7 damage points were recorded along this path by NWS BOU, in the Damage Assessment Toolkit the survey teams carry. The strongest indicator was rated EF1. The highest wind the damage implies is 87 mph.

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

Two colliding outflow boundaries merged over east Denver and northwest Aurora at the height of rush hour. The collision quickly spawned a severe thunderstorm that produced an EF1 tornado, damaging hail, torrential rain and flash flooding. The tornado touched down in east Denver and west Aurora. The tornado first touched down near Quebec and 6th Ave. It then moved east northeast across the Lowry Campus into the west part of Aurora. The tornado then lifted near Mount Nebo Memorial Park. Some homes had minor roof damage with one former apartment building on the Lowry Campus had more significant roof damage. The tornado and intense thunderstorm winds uprooted trees, damaging vehicles and blocking roads. ||The storm produced torrential rain, 2 to 2.5 inches, much of which fell in less than 30 minutes and resulted in flooded intersections and power outages. Flash flooding forced the evacuation of a theater at the Cherry Creek Shopping Center, where drifts of hail formed in the parking lot, and flooding set off alarms at the University of Denver's Ritchie Center. Numerous water rescues were reported as vehicles stalled flooded intersections. Many stoplights were knocked out. The water was reportedly 3-feet deep on the South Broadway ramp to Interstate 25. The bike path along Cherry Creek was inundated with several feet of water at the height of the storm. The South Platte River crested above flood stage for one hour. Employees still at work were urged to stay inside but others waded across flooded intersections downtown. About 30 flights had to be diverted from Denver International Airport.

A tornado touched town near Quebec and 6th Ave and lifted near Mount Nebo Memorial Park. This tornado was a non-supercell tornado. Two outflow boundaries from earlier thunderstorms intersected over eastern Denver and western Aurora. This produced localized convergence and wind shear which likely contributed to the rapid formation of the tornado.

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 20:31 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 Denver radar (KFTG), 29 km away, was scanning. The volume nearest the touchdown began at 22:48 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 2015 tornado in ColoradoEvery tornado in Colorado since 1950Warnings in force in Colorado nowThe forecast where you are

1 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.