Tornadoes · United States · Colorado · 2018

EF2 tornado, Hillrose to Brush Muni Arpt, Colorado, July 29, 2018

From Hillrose to Brush Muni Arpt, this EF2 tornado ran 7.7 miles across Morgan County on July 29, 2018, touching down at 4:37 PM MDT and reaching 500 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.

  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 mph

    Moderate damage. Roofs badly stripped, mobile homes overturned or badly damaged, exterior doors lost, windows broken.

  3. EF2111 to 135 mphthis tornado

    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.

The record

Rating
EF2
Date
July 29, 2018
Touchdown
4:37 PM MDT (22:37 UTC)
Lifted
4:50 PM MDT (22:50 UTC)
On the ground
13 minutes
Path length
7.7 miles (12.3 km)
Path width
500 yards (457 m)
Deaths
0
Injuries
0
County
Morgan County
Touchdown point
40.300, -103.580
Lift-off point
40.190, -103.570
Record number
1807291637-01

The damage survey

3 damage points were recorded along this path by NWS BOU, in the Damage Assessment Toolkit the survey teams carry. The strongest indicator was rated EF2. The highest wind the damage implies is 124 mph.

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

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 and uprooted many trees. Outbuildings were extensively damaged or destroyed.

A tornado touched down and destroyed Brush Municipal Airport. Small planes were flipped over and hangers were leveled. Major tree and roof damage was also observed.

A tornado touched down and snapped power poles and ripped street signs from the ground. This tornado crossed into Washington County before it dissipated.

A tornado touched down and uprooted many trees, with debris striking vehicles.

A tornado touched down and destroyed Brush Municipal Airport. Small planes were flipped over and hangers were leveled. Major tree and roof damage was also observed.

A tornado touched down near the intersection of U.S. 34 and State Highway 71. The tornado snapped power poles and ripped street signs from the ground.

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

The warnings

27 minutes of warning. NWS BOU issued a tornado warning for this county at 22:10 UTC, 27 minutes before the tornado touched down, in force until 22:45 UTC.

The county was under a tornado watch, issued at 19:07 UTC and running to 03:00 UTC.

Issued (UTC)ExpiredProductOffice
19:07 UTC03:00 UTCTornado WatchBOU
22:10 UTC22:45 UTCTornado WarningBOU
22:26 UTC23:00 UTCTornado WarningBOU
22:37 UTC23:00 UTCTornado WarningBOU
22:58 UTC23:23 UTCSevere Thunderstorm WarningBOU
23:01 UTC23:19 UTCTornado WarningBOU

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

10.6 hours before the tornado, 51 km from the path. July 29, 2018.

Skew-T log-pSkew-T log-p diagram, Denver, CO at 12:00Z on 2018-07-29Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel lifted from the surface. Mixed-layer CAPE 181 joules per kilogram, CIN -407, lifted condensation level 1180 meters above ground. Wind barbs in knots down the right edge.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed. The warm shading is its CAPE, the cool shading the inhibition it has to break through.
HodographHodograph, Denver, CO at 12:00Z on 2018-07-29The wind through the lowest 10 kilometers as a curve, rings every 10 meters per second labeled in knots. Zero to 1 km storm-relative helicity 42 square meters per square second, 0 to 6 km bulk shear 33 knots.1939587897Sfc1 km3 km6 km9 kmRMLM
The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km. RM and LM are the right and left moving storms Bunkers' method gives; the shaded area is the 0 to 1 km storm-relative helicity.
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

Open this sounding in Storm Lab

Denver, CO (KDEN), 00:00Z

1.4 hours after it, 51 km from the path. July 30, 2018.

Skew-T log-pSkew-T log-p diagram, Denver, CO at 00:00Z on 2018-07-30Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel lifted from the surface. Mixed-layer CAPE 943 joules per kilogram, CIN -220, lifted condensation level 1653 meters above ground. Wind barbs in knots down the right edge.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed. The warm shading is its CAPE, the cool shading the inhibition it has to break through.
HodographHodograph, Denver, CO at 00:00Z on 2018-07-30The wind through the lowest 10 kilometers as a curve, rings every 10 meters per second labeled in knots. Zero to 1 km storm-relative helicity 101 square meters per square second, 0 to 6 km bulk shear 58 knots.1939587897Sfc1 km3 km6 km9 kmRMLM
The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km. RM and LM are the right and left moving storms Bunkers' method gives; the shaded area is the 0 to 1 km storm-relative helicity.
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

Open this sounding in Storm Lab

The surface observations

Fort Morgan (FMM), 22 km from the path, in the two hours either side.

Time (UTC)Temp (°F)Dew point (°F)WindGust (kt)Pressure (mb)Weather
20:55 UTC78.856.5110° 10 kt141021
21:15 UTC79.256.7110° 6 kt1020.7
21:35 UTC77.257.4110° 16 kt221020.3
21:55 UTC75.258.6120° 16 kt191019.6
22:15 UTC7359150° 11 kt181019.3VCTS
22:35 UTC5750.420° 33 kt421021.7-VCTSRA
22:55 UTC56.35260° 25 kt381021.3-VCTSDZ
23:15 UTC5854.580° 12 kt261022VCTSRA
23:35 UTC6258.370° 15 kt1020.7
23:55 UTC6456.880° 14 kt191020.7
00:15 UTC6556.770° 13 kt201021
00:35 UTC63.557.460° 11 kt1021.3

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

The radar

The Denver radar (KFTG), 97 km away, was scanning. The volume nearest the touchdown began at 22:37 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)ReportWhereCountyRemark
22:48 UTCTORNADO2 Ese BrushMorgan, COSPOTTER REPORTED MANY DOWNED TREES WITH DEBRIS FLYING IN THE AIR AND HITTING HIS CAR.
22:49 UTCTORNADO1 Ne BrushMorgan, COSMALL AIRPORT DESTROYED NEAR BRUSH...PLANES FLIPPED OVER...ROOFS BLOWN OFF HOMES...MAJOR TREE DAMAGE.
22:53 UTCTORNADO2 Ne BrushMorgan, COINTERSECTION OF HIGHWAY 34 AND 71...POWER POLES SNAPPED, STREET SIGNS RIPPED OUT OF THE GROUND.
23:07 UTCTSTM WND GST 74AkronWashington, CO
23:24 UTCTSTM WND DMG7 E AkronWashington, COCORRECTS PREVIOUS TSTM WND GST REPORT FROM 7 E AKRON. SEMI'S BLOWN OVER EAST OF AKRON ALONG HIGHWAY 34.
23:24 UTCTSTM WND GST 07 E AkronWashington, COSEMI'S BLOWN OVER EAST OF AKRON ALONG HIGHWAY 34.
23:40 UTCHAIL 1.753 Nw ElbaWashington, COREPORTED MINOR FLOODING WITH 4 INCHES OF STANDING WATER IN HER YARD.

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.

DateTimeRatingWherePath (mi)Width (yd)DeathsInjuriesDamage
July 291:55 PM MDTEF0Laramie, WY1.075
July 292:20 PM MDTEF0Oglala Lakota, SD0.010
July 292:45 PM MDTEF0Laramie, WY0.250
July 293:28 PM MDTEF0Weld, CO0.050
July 294:31 PM MDTEF2Morgan, CO8.6400
July 294:47 PM MDTEF2Morgan, CO7.1300

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.