Tornadoes · United States · California · 2018

EF0 tornado, Anza, California, August 16, 2018

This EF0 tornado ran 0.2 miles across Riverside County on August 16, 2018, touching down at 3:00 PM PDT and reaching 2 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 16, 2018
Touchdown
3:00 PM PDT (22:00 UTC)
Lifted
3:30 PM PDT (22:30 UTC)
On the ground
30 minutes
Path length
0.2 miles (0.4 km)
Path width
2 yards (2 m)
Deaths
0
Injuries
0
County
Riverside County
Touchdown point
33.562, -116.686
Lift-off point
33.562, -116.690
Record number
1808161600-01

What the Weather Service recorded

Monsoonal moisture moved into Southern California on August 15th and resulted in numerous showers and thunderstorms across the region. Heavy rain fell in the San Diego County Mountains on August 15th, and became more widespread on August 16th and 17th. Mount Laguna picked up 3.20 inches of rainfall on August 17th. Numerous areas of flash flooding and debris flows were reported throughout Southern California, particularly in the Riverside and San Bernardino County mountain areas. A landspout tornado was reported in the Anza Valley associated with a severe thunderstorm. No injuries or major damages were reported.

Public reports of a landspout tornado northwest of Anza, CA. No injuries or damages were reported.

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
17:42 UTC03:00 UTCFlash Flood WatchSGX
19:45 UTC23:00 UTCFlash Flood WarningSGX
19:54 UTC23:00 UTCFlash Flood WarningPSR
20:58 UTC22:00 UTCSevere Thunderstorm WarningSGX
21:24 UTC00:30 UTCFlood AdvisoryPSR
21:30 UTC22:47 UTCFlash Flood WarningSGX
21:34 UTC22:30 UTCSevere Thunderstorm WarningSGX
22:04 UTC01:00 UTCFlash Flood WarningPSR
00:26 UTC03:30 UTCFlood AdvisoryPSR

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 19:50 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.

San Diego, CA (KNKX), 12:00Z

10.0 hours before the tornado, 97 km from the path. August 16, 2018.

Skew-T log-pSkew-T log-p diagram, San Diego, CA at 12:00Z on 2018-08-16Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel lifted from the surface. Mixed-layer CAPE 0 joules per kilogram, CIN -74874, lifted condensation level 810 meters above ground. Wind barbs in knots down the right edge.LCL10008507005003002001001 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, San Diego, CA at 12:00Z on 2018-08-16The 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 -17 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
0 J/kg
Mixed-layer CIN
-74874 J/kg
Surface CAPE
0 J/kg
Mixed-layer LCL
810 m above ground
0-6 km bulk shear
11 kt
0-1 km bulk shear
5 kt
0-1 km storm-relative helicity
-17 m²/s²
0-3 km storm-relative helicity
-3 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0
0-3 km lapse rate
3.0 K/km

Open this sounding in Storm Lab

San Diego, CA (KNKX), 00:00Z

2.0 hours after it, 97 km from the path. August 17, 2018.

Skew-T log-pSkew-T log-p diagram, San Diego, CA at 00:00Z on 2018-08-17Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel lifted from the surface. Mixed-layer CAPE 0 joules per kilogram, CIN -76970, lifted condensation level 954 meters above ground. Wind barbs in knots down the right edge.LCL10008507005003002001001 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, San Diego, CA at 00:00Z on 2018-08-17The 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 3 square meters per square second, 0 to 6 km bulk shear 4 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
0 J/kg
Mixed-layer CIN
-76970 J/kg
Surface CAPE
0 J/kg
Mixed-layer LCL
954 m above ground
0-6 km bulk shear
4 kt
0-1 km bulk shear
8 kt
0-1 km storm-relative helicity
3 m²/s²
0-3 km storm-relative helicity
76 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0
0-3 km lapse rate
5.4 K/km

Open this sounding in Storm Lab

The surface observations

Palm Springs Regional (PSP), 34 km from the path, in the two hours either side.

Time (UTC)Temp (°F)Dew point (°F)WindGust (kt)Pressure (mb)Weather
20:00 UTC80° 10 kt1013.9
20:05 UTC70° 9 kt1014.2
20:10 UTC100° 9 kt1013.9
20:15 UTC120° 11 kt1013.9
20:20 UTC110° 12 kt1013.9
20:25 UTC120° 11 kt1014.2
20:30 UTC90° 11 kt1014.2
20:35 UTC130° 11 kt1013.9
20:40 UTC120° 9 kt1013.9
20:43 UTC9970100° 11 kt1013.9VCTS
20:45 UTC110° 8 kt1013.9
20:50 UTC140° 9 kt1013.9
20:53 UTC996990° 12 kt1013.9
20:55 UTC110° 12 kt1013.9
21:00 UTC130° 9 kt1013.9
21:01 UTC9869110° 10 kt1013.9VCTS
21:05 UTC110° 9 kt1013.9
21:10 UTC110° 10 kt1013.9
21:15 UTC70° 7 kt1013.9
21:20 UTC90° 4 kt1013.9
21:25 UTC100° 5 kt1013.5
21:30 UTC130° 7 kt1013.5
21:35 UTC110° 5 kt1013.5
21:36 UTC9968110° 6 kt1013.5
21:40 UTC80° 5 kt1013.5
21:45 UTC120° 6 kt1013.5
21:50 UTC90° 5 kt1013.5
21:53 UTC9868100° 3 kt1013.5
21:55 UTC0° 0 kt1013.5
22:00 UTC80° 3 kt1013.2
22:05 UTC160° 3 kt1013.2
22:08 UTC99680° 0 kt1013.2VCTS
22:10 UTC20° 3 kt1013.2
22:15 UTC150° 3 kt1012.9
22:20 UTC180° 6 kt1012.9
22:23 UTC9968140° 6 kt1012.9
22:25 UTC120° 3 kt1012.5
22:30 UTC0° 0 kt1012.5
22:35 UTC130° 3 kt1012.5
22:40 UTC100° 3 kt1012.2
22:45 UTC60° 3 kt1012.2
22:50 UTC60° 3 kt1012.2
22:53 UTC1016990° 3 kt1012.5
22:55 UTC140° 3 kt1012.5
23:00 UTC170° 3 kt1012.5
23:05 UTC190° 3 kt1012.5
23:10 UTC0° 0 kt1012.5
23:15 UTC0° 0 kt1012.5
23:20 UTC300° 3 kt1012.5
23:25 UTC0° 0 kt1012.5
23:30 UTC0° 0 kt1012.5
23:35 UTC310° 4 kt1012.5
23:40 UTC270° 3 kt1012.5
23:45 UTC310° 3 kt1012.2
23:50 UTC320° 4 kt1012.2
23:53 UTC9969 4 kt1012.2
23:55 UTC0° 0 kt1012.2

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

The radar

The San Diego radar (KNKX), 79 km away, was scanning. The volume nearest the touchdown began at 21:58 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
21:35 UTCFLASH FLOOD1 Se Cherry ValleyRiverside, CACHP REPORTS BROOKSIDE AVE AND HIGHLAND SPRINGS AVE FLOODED OUT ON BOTH SIDES OF THE ROAD.
21:37 UTCFLOOD1 Se Cherry ValleyRiverside, CACHP REPORTS ROAD FLOODED ON BOTH SIDES AT INTERSECTION OF BROOKSIDE AVE /HIGHLAND SPRINGS AVE IN BEAUMONT.
22:30 UTCTORNADO11 Sse Mountain CenterRiverside, CAMULTIPLE PHOTOS OF LANDSPOUT TORNADO ASSOCIATED WITH SEVERE THUNDERSTORM OVER ANZA VALLEY.
22:50 UTCDEBRIS FLOW3 Wsw Mountain CenterRiverside, CACALTRANS REPORTED DOZENS OF DEBRIS FLOWS NEAR THE CRANSTON FIRE BURN SCAR, SOME OF THEM FLOWING ONTO HWY 74.

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 CaliforniaEvery tornado in California since 1950Warnings in force in California nowThe forecast where you are

The other tornadoes of August 16, 2018

3 more were confirmed in the United States that day.

DateTimeRatingWherePath (mi)Width (yd)DeathsInjuriesDamage
August 164:38 PM CDTEF0Fulton, IL3.1100$30,000
August 166:08 PM CDTEF0Jones, IA0.010
August 167:30 PM CDTEF0Barton, KS0.450

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.