EF0 tornado, Greeley Arpt to Gill, Colorado, May 20, 2020

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

May 20, 2020

Touchdown

6:45 PM MDT (00:45 UTC)

Lifted

6:56 PM MDT (00:56 UTC)

On the ground

11 minutes

Path length

4.0 miles (6.4 km)

Path width

50 yards (46 m)

Deaths

0

Injuries

0

County

Weld County

Touchdown point

40.451, -104.604

Lift-off point

40.493, -104.658

Record number

2005201845-01

Six EF-0 landspout tornadoes occurred in Weld County in the span of approximately one hour. The tornadoes tracked in a southeast to northwest direction over open country in an area from 5 miles east of Greeley to just east of Eaton. Three lasted less than 10 minutes, and the longest lived tornado was on the ground for 25 minutes and had a track length of 8 miles. Three farmsteads were impacted with minor damage, and there were no injuries or deaths.

A landspout touched down briefly in an open field. No damage was observed.

A brief landspout caused minor damage to a farmstead. The tornado touched down just west of Weld Co 74/41. Barn doors were blown it and a fiberglass canoe lofted into a tree.

A landspout touched down near a farmstead and caused minor damage. It struck an irrigation pivot and twisted it.

A landspout touched down and caused minor damage to a farm located north of CO-392.|One aluminum shed sustained serious damaged.

A landspout tornado touched down and caused minor damage an older barn near county roads 72 and 43. The damage consisted of a wall blown over from an outbuilding.

A tornado touched down briefly in an open field. No damage was observed.

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.

The county was under a severe thunderstorm watch, issued at 20:23 UTC and running to 04:00 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 Marginal Risk, with a 0.02 chance of a tornado within 25 miles. 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 Denver radar (KFTG), 77 km away, was scanning. The volume nearest the touchdown began at 00:43 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 2020 tornado in ColoradoEvery tornado in Colorado since 1950Warnings in force in Colorado nowThe forecast where you are

7 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.