Tornadoes · United States · Texas · 2021

EF0 tornado, Cypress, Texas, August 12, 2021

This EF0 tornado ran 0.3 miles across Harris County on August 12, 2021, touching down at 4:32 PM CDT and reaching 10 yards wide. It killed nobody, and did $5,000 of property damage.

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 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.

The record

Rating
EF0
Date
August 12, 2021
Touchdown
4:32 PM CDT (21:32 UTC)
Lifted
4:34 PM CDT (21:34 UTC)
On the ground
2 minutes
Path length
0.3 miles (0.4 km)
Path width
10 yards (9 m)
Deaths
0
Injuries
0
Property damage
$5,000
County
Harris County
Touchdown point
29.922, -95.728
Lift-off point
29.927, -95.728
Record number
2108121532-01

What the Weather Service recorded

There was a tornado near Cypress.

Law enforcement and multiple spotters reported five power poles were downed by a brief EF0 landspout tornado.

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.

Issued (UTC)ExpiredProductOffice
21:35 UTC22:00 UTCTornado WarningHGX

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 General Thunderstorms Risk. The outlook in force was issued at 19:58 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.

Lake Charles Mun, LA (KLCH), 12:00Z

9.5 hours before the tornado, 244 km from the path. August 12, 2021.

Skew-T log-pSkew-T log-p diagram, Lake Charles Mun, LA at 12:00Z on 2021-08-12Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel lifted from the surface. Mixed-layer CAPE 2387 joules per kilogram, CIN -16, lifted condensation level 813 meters above ground. Wind barbs in knots down the right edge.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°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, Lake Charles Mun, LA at 12:00Z on 2021-08-12The 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 -48 square meters per square second, 0 to 6 km bulk shear 6 knots.1939Sfc1 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
2387 J/kg
Mixed-layer CIN
-16 J/kg
Surface CAPE
2378 J/kg
Mixed-layer LCL
813 m above ground
0-6 km bulk shear
6 kt
0-1 km bulk shear
11 kt
0-1 km storm-relative helicity
-48 m²/s²
0-3 km storm-relative helicity
0 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0
0-3 km lapse rate
4.7 K/km

Open this sounding in Storm Lab

Lake Charles Mun, LA (KLCH), 00:00Z

2.5 hours after it, 244 km from the path. August 13, 2021.

Skew-T log-pSkew-T log-p diagram, Lake Charles Mun, LA at 00:00Z on 2021-08-13Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel lifted from the surface. Mixed-layer CAPE 897 joules per kilogram, CIN -34, lifted condensation level 1271 meters above ground. Wind barbs in knots down the right edge.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°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, Lake Charles Mun, LA at 00:00Z on 2021-08-13The 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 7 square meters per square second, 0 to 6 km bulk shear 13 knots.1939Sfc1 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
897 J/kg
Mixed-layer CIN
-34 J/kg
Surface CAPE
2620 J/kg
Mixed-layer LCL
1271 m above ground
0-6 km bulk shear
13 kt
0-1 km bulk shear
2 kt
0-1 km storm-relative helicity
7 m²/s²
0-3 km storm-relative helicity
11 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0
0-3 km lapse rate
6.6 K/km

Open this sounding in Storm Lab

The surface observations

Houston Exec (TME), 21 km from the path, in the two hours either side.

Time (UTC)Temp (°F)Dew point (°F)WindGust (kt)Pressure (mb)Weather
19:35 UTC9575.2170° 6 kt1017.9
19:55 UTC96.877190° 14 kt191017.9
20:15 UTC91.475.2220° 13 kt1017.9
20:35 UTC91.475.2230° 10 kt1017.6
20:55 UTC93.275.2200° 11 kt1017.3
21:15 UTC9577240° 10 kt1016.9
21:35 UTC9575.2210° 8 kt131017.3
21:55 UTC93.273.4200° 7 kt131016.9
22:15 UTC91.475.2200° 7 kt1016.9
22:35 UTC91.473.4210° 7 kt1016.6
22:55 UTC91.475.2200° 6 kt1016.6
23:15 UTC91.475.2200° 8 kt1016.6

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

The radar

The Houston radar (KHGX), 80 km away, was scanning. The volume nearest the touchdown began at 21:30 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
21:37 UTCTORNADO5 Sw CypressHarris, TXHarris County Pct. 5 constables reporting tornado. Airborne debris and 5 telephone poles downed.
21:37 UTCTORNADO5 Sw CypressHarris, TXHARRIS COUNTY PCT. 5 CONSTABLES REPORTING TORNADO. AIRBORNE DEBRIS AND 5 TELEPHONE POLES DOWNED.

From the Iowa Environmental Mesonet's archive of National Weather Service local storm reports.

This ground now

The live radar over the trackEvery 2021 tornado in TexasEvery tornado in Texas since 1950Warnings in force in Texas nowThe forecast where you are

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.