Tornadoes · United States · Arizona · 2019

EF0 tornado, Three Pts, Arizona, August 10, 2019

This EF0 tornado ran 0.2 miles across Pima County on August 10, 2019, touching down at 1:00 PM MST and reaching 10 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 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 10, 2019
Touchdown
1:00 PM MST (20:00 UTC)
Lifted
1:03 PM MST (20:03 UTC)
On the ground
3 minutes
Path length
0.2 miles (0.3 km)
Path width
10 yards (9 m)
Deaths
0
Injuries
0
County
Pima County
Touchdown point
32.115, -111.320
Lift-off point
32.116, -111.323
Record number
1908101400-01

What the Weather Service recorded

Scattered thunderstorms produced moderate to locally heavy rain in southeast Arizona. The result was flash flooding in the Mammoth and the Safford areas. There was also a landspout tornado north of Three Points.

Landspout tornado formed north of Three Points and persisted for 3 minutes.

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.

Issued (UTC)ExpiredProductOffice
08:00 UTC12:00 UTCFlash Flood WatchTWC
18:27 UTC19:30 UTCFlood AdvisoryTWC
18:57 UTC19:29 UTCSevere Thunderstorm WarningTWC
19:36 UTC00:43 UTCFlood AdvisoryTWC
20:14 UTC23:15 UTCFlash Flood WarningTWC
20:24 UTC23:45 UTCFlood AdvisoryTWC
21:40 UTC00:45 UTCFlash Flood WarningTWC
22:06 UTC01:00 UTCFlood AdvisoryTWC

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 19:35 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.

Tuscon, AZ (KTUS), 12:00Z

8.0 hours before the tornado, 40 km from the path. August 10, 2019.

Skew-T log-pSkew-T log-p diagram, Tuscon, AZ at 12:00Z on 2019-08-10Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel lifted from the surface. Mixed-layer CAPE 250 joules per kilogram, CIN -100, lifted condensation level 1947 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, Tuscon, AZ at 12:00Z on 2019-08-10The 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 -8 square meters per square second, 0 to 6 km bulk shear 2 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
250 J/kg
Mixed-layer CIN
-100 J/kg
Surface CAPE
120 J/kg
Mixed-layer LCL
1947 m above ground
0-6 km bulk shear
2 kt
0-1 km bulk shear
6 kt
0-1 km storm-relative helicity
-8 m²/s²
0-3 km storm-relative helicity
49 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0
0-3 km lapse rate
7.1 K/km

Open this sounding in Storm Lab

Tuscon, AZ (KTUS), 00:00Z

4.0 hours after it, 40 km from the path. August 11, 2019.

Skew-T log-pSkew-T log-p diagram, Tuscon, AZ at 00:00Z on 2019-08-11Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel lifted from the surface. Mixed-layer CAPE 252 joules per kilogram, CIN -126, lifted condensation level 987 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, Tuscon, AZ at 00:00Z on 2019-08-11The 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 -13 square meters per square second, 0 to 6 km bulk shear 11 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
252 J/kg
Mixed-layer CIN
-126 J/kg
Surface CAPE
992 J/kg
Mixed-layer LCL
987 m above ground
0-6 km bulk shear
11 kt
0-1 km bulk shear
3 kt
0-1 km storm-relative helicity
-13 m²/s²
0-3 km storm-relative helicity
88 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0
0-3 km lapse rate
5.6 K/km

Open this sounding in Storm Lab

The radar

The Tucson radar (KEMX), 70 km away, was scanning. The volume nearest the touchdown began at 20:02 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
18:54 UTCHEAVY RAIN 0.55 E TucsonPima, AZREPORTED BY PUBLIC VIA TWITTER.
19:06 UTCHEAVY RAIN 0.565 Ene TucsonPima, AZSPOTTER 1774A REPORTED RAINFALL MEASUREMENT VIA TWITTER.
19:13 UTCHEAVY RAIN 0.617 N TucsonPima, AZSPOTTER 1878A REPORTED RAINFALL MEASUREMENT VIA TWITTER.
19:35 UTCHEAVY RAIN 0.518 Ese TucsonPima, AZSPOTTER 1861A REPORTED RAINFALL MEASUREMENT VIA TWITTER.
20:45 UTCFLOOD4 E TucsonPima, AZATTERBURY WASH IS CLOSED AT ESCALANTE RD. DUE TO PONDING WATER.
20:50 UTCHEAVY RAIN 1.511 Ssw Oro ValleyPima, AZ1.5 INCHES OF RAIN FELL IN AN HOUR AND A HALF.
21:34 UTCHEAVY RAIN 1.756 W Picture RocksPima, AZ1.75 INCHES OF RAIN IN THE LAST HOUR; BLANCO WASH TRAIL IS FULL, AND TUCKER ROAD IS IMPACTED.

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

This ground now

The live radar over the trackEvery 2019 tornado in ArizonaEvery tornado in Arizona since 1950Warnings in force in Arizona nowThe forecast where you are

The other tornadoes of August 10, 2019

2 more were confirmed in the United States that day.

DateTimeRatingWherePath (mi)Width (yd)DeathsInjuriesDamage
August 106:06 PM CDTEF0Cottonwood, MN1.450
August 106:36 PM CDTEF0Martin, MN0.025

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.