EF0 tornado, Stanfield, Arizona, September 23, 2019

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

September 23, 2019

Touchdown

6:23 PM MST (01:23 UTC)

Lifted

6:25 PM MST (01:25 UTC)

On the ground

2 minutes

Path length

0.5 miles (0.9 km)

Path width

50 yards (46 m)

Deaths

0

Injuries

0

County

Pinal County

Touchdown point

32.870, -111.880

Lift-off point

32.876, -111.874

Record number

1909231923-01

Significant amounts of tropical moisture spread north and into south central Arizona on September 23rd; the moisture interacted with a strong upper low west of Phoenix to produce numerous showers and thunderstorms during the morning and afternoon hours. Many of the storms generated very heavy rain which led to multiple episodes of flash flooding. However, there were a few storms that became severe, due to favorable environmental conditions including elevated instability and strong wind shear with height. In addition to the typical monsoonal weather hazards such as gusty outflow winds, one of the storms managed to produce a weak tornado, which is very unusual for southern Arizona. The tornado formed near New River around noon, and actually produced modest damage. The tornado stayed on the ground for nearly one mile. No injuries were reported but the tornado generated significant media attention due to its rarity.

Scattered to numerous showers and thunderstorms continued to develop across the central deserts during the afternoon hours on September 23rd. In addition to producing very heavy rain, one exceptionally strong storm actually produced a weak tornado between Stanfield and Casa Grande during the late afternoon. Atmospheric conditions were especially favorable for weak tornadoes, given the elevated instability combined with much stronger than normal wind shear with height. In this case, a trained spotter viewed the weak landspout tornado over an open field; it quickly dissipated near State Route 84 and Midway Road. The tornado occurred at approximately 1825MST. Fortunately the tornado did not produce any damage or injuries.

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 16:52 UTC and running to 03:00 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 Slight Risk, with a 0.02 chance of a tornado within 25 miles. The outlook in force was issued at 00:29 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.

Maricopa - Ak-chin (A39), 14 km from the path, in the two hours either side.

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

The Phoenix radar (KIWA), 50 km away, was scanning. The volume nearest the touchdown began at 01:25 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 2019 tornado in ArizonaEvery tornado in Arizona since 1950Warnings in force in Arizona nowThe forecast where you are

2 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.