Tornadoes · United States · Colorado · 2018
EF0 tornado, Pawnee Buttes, Colorado, July 29, 2018
This EF0 tornado ran 0.0 miles across Weld County on July 29, 2018, touching down at 3:28 PM MDT and reaching 50 yards wide. It killed nobody.
The rating scale
Tracks are drawn in the color of the rating. The Enhanced Fujita scale rates the damage rather than measuring the wind: the speeds are what that damage is taken to imply.
EF065 to 85 mphthis tornado
Light damage. Surface peeled off some roofs, gutters and siding damaged, branches broken, shallow-rooted trees pushed over.
EF186 to 110 mph
Moderate damage. Roofs badly stripped, mobile homes overturned or badly damaged, exterior doors lost, windows broken.
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.
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.
EF4166 to 200 mph
Devastating damage. Well-built houses leveled, structures with weak foundations moved some distance, cars thrown and large missiles generated.
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.
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.
The record
- Rating
- EF0
- Date
- July 29, 2018
- Touchdown
- 3:28 PM MDT (21:28 UTC)
- Lifted
- 3:29 PM MDT (21:29 UTC)
- On the ground
- 1 minutes
- Path length
- 0.0 miles (0.0 km)
- Path width
- 50 yards (46 m)
- Deaths
- 0
- Injuries
- 0
- County
- Weld County
- Touchdown point
- 40.830, -103.770
- Lift-off point
- 40.830, -103.770
- Record number
- 1807291528-01
What the Weather Service recorded
Severe thunderstorms brought damaging tornadoes, straight-line winds, large hail and heavy rain across northeast Colorado. A total of 4 tornadoes touched down and impacted the communities of Brush, Hillrose, and Snyder. An EF-2 tornado struck the east side of Brush and caused significant damage to the Brush Airport and turned semi-trucks on their side on U.S. 34. Highway 34, was closed near the Morgan-Washington county line due to debris and downed power lines. In Hillrose and Snyder moderate damage to structures included: roofs, windows, siding, broken trees, power lines and piles down. In Snyder, the town hall was also damaged and some roadways were inundated with over 3 feet of standing water. In Snyder, a tornado touched down in the Pinneno feedlot, which injured and killed livestock. Heavy agricultural damage to crops was reported and pivots were destroyed. ||In Morgan County, over 200 poles down were knocked down and caused extensive power outages across the area. Those affected by the tornados were expected to be without power for up to 2 days. Approximately 20 people suffered mainly minor injuries. The hail ranged in size from quarter to baseball size, and produced peak wind gusts to around 75 mph. Multiple road closures were reported around Morgan County due to flooded roadways and downed power lines. As the storm continued east, near-zero visibility rain fell in Akron, which was accompanied by strong winds. In the southern portion of Washington County, the storm produced hail up to baseball size south of Anton. There was also widely spread damage to crops, vehicles, roofs, siding, and windows. In Greeley, reports of damage included broken windshields and destroyed gardens.
A tornado touched down briefly but no damage was observed.
From NOAA NCEI's Storm Events Database, the narrative the local forecast office wrote for Storm Data.
The warnings
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 19:07 UTC and running to 03:00 UTC.
| Issued (UTC) | Expired | Product | Office |
|---|---|---|---|
| 19:07 UTC | 03:00 UTC | Tornado Watch | BOU |
| 20:47 UTC | 21:15 UTC | Tornado Warning | BOU |
| 21:06 UTC | 21:45 UTC | Severe Thunderstorm Warning | BOU |
| 21:16 UTC | 22:00 UTC | Severe Thunderstorm Warning | BOU |
| 21:32 UTC | 22:15 UTC | Tornado Warning | BOU |
| 21:44 UTC | 22:30 UTC | Severe Thunderstorm Warning | BOU |
| 22:00 UTC | 22:30 UTC | Tornado Warning | BOU |
| 22:10 UTC | 22:45 UTC | Tornado Warning | BOU |
| 22:26 UTC | 23:00 UTC | Tornado Warning | BOU |
| 22:31 UTC | 23:00 UTC | Severe Thunderstorm Warning | BOU |
| 00:43 UTC | 01:15 UTC | Severe Thunderstorm Warning | BOU |
| 01:04 UTC | 01:30 UTC | Severe Thunderstorm Warning | BOU |
| 01:28 UTC | 02:00 UTC | Severe Thunderstorm Warning | BOU |
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 forecast that day
The Storm Prediction Center had this point in a Enhanced Risk, with a 0.10 chance of a tornado within 25 miles. The outlook in force was issued at 19:54 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 air that afternoon
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.
Denver, CO (KDEN), 12:00Z
9.5 hours before the tornado, 116 km from the path. July 29, 2018.
- Mixed-layer CAPE
- 181 J/kg
- Mixed-layer CIN
- -407 J/kg
- Surface CAPE
- 170 J/kg
- Mixed-layer LCL
- 1180 m above ground
- 0-6 km bulk shear
- 33 kt
- 0-1 km bulk shear
- 6 kt
- 0-1 km storm-relative helicity
- 42 m²/s²
- 0-3 km storm-relative helicity
- 208 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
- 0-3 km lapse rate
- 4.2 K/km
Denver, CO (KDEN), 00:00Z
2.5 hours after it, 116 km from the path. July 30, 2018.
- Mixed-layer CAPE
- 943 J/kg
- Mixed-layer CIN
- -220 J/kg
- Surface CAPE
- 1906 J/kg
- Mixed-layer LCL
- 1653 m above ground
- 0-6 km bulk shear
- 58 kt
- 0-1 km bulk shear
- 11 kt
- 0-1 km storm-relative helicity
- 101 m²/s²
- 0-3 km storm-relative helicity
- 191 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 1.8
- 0-3 km lapse rate
- 7.3 K/km
The radar
The Cheyenne radar (KCYS), 94 km away, was scanning. The volume nearest the touchdown began at 21:26 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.
What was reported nearby
Local storm reports within 60 km of the path, in the three hours either side.
| Time (UTC) | Report | Where | County | Remark |
|---|---|---|---|---|
| 21:27 UTC | TSTM WND GST 59 | 4 Nnw Pawnee Buttes | Weld, CO | |
| 21:29 UTC | HAIL 1.75 | 4 Nw Pawnee Buttes | Weld, CO | |
| 21:29 UTC | TORNADO | 11 E Pawnee Buttes | Weld, CO | BRIEF TORNADO TOUCHDOWN. HAS SINCE LIFTED. |
| 21:47 UTC | HAIL 2.5 | 14 Nw New Raymer | Weld, CO | CORRECTS PREVIOUS HAIL REPORT FROM 14 NW NEW RAYMER. |
| 21:47 UTC | HAIL 2.5 | 14 Nw New Raymer | Weld, CO |
From the Iowa Environmental Mesonet's archive of National Weather Service local storm reports.
This ground now
The live radar over the trackEvery 2018 tornado in ColoradoEvery tornado in Colorado since 1950Warnings in force in Colorado nowThe forecast where you are
The other tornadoes of July 29, 2018
6 more were confirmed in the United States that day.
What this means
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.
Sources
NOAA Storm Prediction Center tornado database, 1950-2025, the official record kept by NOAA's Storm Prediction Center.