Tornadoes · United States · California · 2011

EF2 tornado, Thermalito, California, May 25, 2011

This EF2 tornado ran 0.2 miles across Butte County on May 25, 2011, touching down at 6:45 PM PDT and reaching 10 yards wide. It killed nobody, and did $120,000 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 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
May 25, 2011
Touchdown
6:45 PM PDT (01:45 UTC)
Lifted
6:48 PM PDT (01:48 UTC)
On the ground
3 minutes
Path length
0.2 miles (0.3 km)
Path width
10 yards (9 m)
Deaths
0
Injuries
0
Property damage
$120,000
County
Butte County
Touchdown point
39.598, -121.621
Lift-off point
39.599, -121.617
Record number
1105251945-01

What the Weather Service recorded

Three tornadoes moved through Glenn and Butte Counties the evening of May 25, 2011. Significant damage was caused to several structures and thousands of almond trees were destroyed.

The third tornado in the outbreak developed approximately northwest of Oroville in Butte County at approximately 645 pm and moved northeast. It caused significant damage to a ranch property near the intersection of Table Mountain Road and Hwy 70 including the destruction of a large, well built garage and significant damage to an open barn. The rating of an EF2 was based upon the destruction of the garage, though evidence was found of the footing boards being bolted to the slab in the front portion of the structure. The estimated highest wind speed (3 second gust) based upon damage with this tornado is 120 mph. There were no injuries nor fatalities.

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

The warnings

35 minutes of warning. NWS STO issued a tornado warning for this county at 01:10 UTC, 35 minutes before the tornado touched down, in force until 01:45 UTC.

Issued (UTC)ExpiredProductOffice
00:12 UTC01:15 UTCTornado WarningSTO
01:10 UTC01:45 UTCTornado WarningSTO
01:45 UTC02:30 UTCTornado WarningSTO

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 00:57 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.

Oakland, CA (KOAK), 00:00Z

1.8 hours before the tornado, 214 km from the path. May 26, 2011.

Skew-T log-pSkew-T log-p diagram, Oakland, CA at 00:00Z on 2011-05-26Temperature 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 -57700, lifted condensation level 1378 meters above ground. Wind barbs in knots down the right edge.LCL10008507005003002001001 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, Oakland, CA at 00:00Z on 2011-05-26The 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 83 knots.1939587897117Sfc1 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
-57700 J/kg
Surface CAPE
39 J/kg
Mixed-layer LCL
1378 m above ground
0-6 km bulk shear
83 kt
0-1 km bulk shear
9 kt
0-1 km storm-relative helicity
-3 m²/s²
0-3 km storm-relative helicity
184 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0
0-3 km lapse rate
7.0 K/km

Open this sounding in Storm Lab

Oakland, CA (KOAK), 12:00Z

10.2 hours after it, 214 km from the path. May 26, 2011.

Skew-T log-pSkew-T log-p diagram, Oakland, CA at 12:00Z on 2011-05-26Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel lifted from the surface. Mixed-layer CAPE 30 joules per kilogram, CIN -4, lifted condensation level 575 meters above ground. Wind barbs in knots down the right edge.LCLEL10008507005003002001001 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, Oakland, CA at 12:00Z on 2011-05-26The 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 50 square meters per square second, 0 to 6 km bulk shear 73 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
30 J/kg
Mixed-layer CIN
-4 J/kg
Surface CAPE
14 J/kg
Mixed-layer LCL
575 m above ground
0-6 km bulk shear
73 kt
0-1 km bulk shear
11 kt
0-1 km storm-relative helicity
50 m²/s²
0-3 km storm-relative helicity
50 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0
0-3 km lapse rate
3.1 K/km

Open this sounding in Storm Lab

The radar

The Beale AFB radar (KBBX), 11 km away, was scanning. The volume nearest the touchdown began at 01:46 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
23:35 UTCHAIL 0.56 N WillowsGlenn, CAMARBLE SIZE HAIL REPORTED ON INTERSTATE 5 BY CHP UNIT NEAR ARTOIS.
23:50 UTCHAIL 0.755 Ne WillowsGlenn, CAREPORTED COVERING THE GROUND NEAR BLUE GUM AT THE SIERRA NEVADA CHEESE COMPANY.
00:12 UTCTORNADO1 Ene WillowsGlenn, CAGLENN COUNTY SHERIFF REPORTED A TORNADO NORTHEAST OF WILLOWS NEAR COUNTY ROAD 36 AND U STREET.
00:18 UTCTORNADO2 S Hamilton CityGlenn, CAGLENN COUNTY SHERIFF REPORTED A TORNADO JUST SOUTH OF HAMILTON CITY.
01:08 UTCTORNADO10 Sw ChicoButte, CATORNADO ON THE GROUND FILMED LIVE BY MEDIA HELICOPTER SOUTHEAST OF ORD BEND.
01:20 UTCTORNADO8 Ssw ChicoButte, CATORNADO ON THE GROUND FILMED LIVE BY MEDIA HELICOPTERS NEAR DURHAM.
01:35 UTCFUNNEL CLOUD2 E ChicoButte, CA
01:40 UTCTORNADO9 Nw OrovilleButte, CATREES DOWN ON TAYLOR AVE. JUST SOUTH OF THE TOWN OF DURHAM.
02:00 UTCTSTM WND DMG7 Nw OrovilleButte, CAPOSSIBLE OUTBUILDING/BARN TORNADO DAMAGE AT 2910 TABLE MOUNTAIN BLVD.
02:00 UTCHAIL 0.888 Ssw ParadiseButte, CA
02:00 UTCTORNADO7 Nw OrovilleButte, CAOUTBUILDING/BARN/DETACHED GARAGE/TREE DAMAGE AT TABLE MOUNTAIN BLVD.
02:00 UTCTORNADO8 Ssw ParadiseButte, CAOBSERVER SPOTTED TORNADO APPROX. 1 MILE SOUTH.
02:10 UTCHAIL 18 Ssw ParadiseButte, CA
02:20 UTCFUNNEL CLOUD8 Nnw OrovilleButte, CA
02:23 UTCFUNNEL CLOUD4 Ne DurhamButte, CAFUNNEL CLOUD HANGING OVER TOWN OF DURHAM FOR 10 MINUTES.

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

This ground now

The live radar over the trackEvery 2011 tornado in CaliforniaEvery tornado in California since 1950Warnings in force in California nowThe forecast where you are

The other tornadoes of May 25, 2011

93 more were confirmed in the United States that day.

DateTimeRatingWherePath (mi)Width (yd)DeathsInjuriesDamage
May 251:30 AM CDTEF1Webster, MO9.3100$20,000
May 257:35 AM CDTEF1Macon, IL1.075$165,000
May 257:39 AM CDTEF1Macon, IL1.575$100,000
May 259:04 AM CDTEF1Kankakee, IL5.850$250,000
May 259:13 AM CDTEF0Newton, IN0.120$25,000
May 259:19 AM CDTEF2Newton, IN1.9300$50,000
May 259:24 AM CDTEF1Jasper, IN2.9100$500
May 259:26 AM CDTEF1Jasper, IN1.9100$50,000
May 2510:45 AM EDTEF0Pulaski, IN0.850
May 2510:45 AM CDTEF0Miami, KS0.140$5,000
May 2511:10 AM CDTEF0Johnson, KS0.760$10,000
May 2511:22 AM CDTEF0Johnson, KS0.140
May 2511:35 AM CDTEF0Cass, MO0.140
May 2511:38 AM CDTEF0Johnson, KS0.140
May 2512:22 PM CDTEF2Pettis, MO2.150020$4.0 million
May 2512:33 PM CDTEF0Clay, MO0.140
May 2512:45 PM CDTEF0Clay, MO0.140
May 2512:52 PM CDTEF0Pettis, MO0.140
May 251:04 PM CDTEF0Cooper, MO0.140
May 251:07 PM CDTEF0Lafayette, MO0.140
May 252:15 PM CDTEF1Montgomery, MO7.1100
May 253:26 PM EDTEF0Van Wert, OH0.140
May 252:56 PM CDTEF1Oregon, MO2.5100$20,000
May 253:49 PM CDTEF3Carter, MO47.41,2002$800,000
May 254:13 PM CDTEF1Jackson, AR5.5500$40,000
May 255:15 PM EDTEF1Decatur, IN0.8600$500,000
May 255:20 PM EDTEF1Decatur, IN0.1400$250,000
May 254:35 PM CDTEF1Madison, MO5.540
May 254:37 PM CDTEF1Wayne, MO17.8150$70,000
May 254:44 PM CDTEF0Carter, MO0.550$2,000
May 254:45 PM CDTEF1Des Moines, IA4.8100$250,000
May 254:46 PM CDTEF1Madison, MO5.3440
May 254:47 PM CDTEF1Madison, MO4.3580
May 254:51 PM CDTEF0Perry, MO0.360$3,000
May 254:58 PM CDTEF0Ripley, MO0.750
May 256:00 PM EDTEF1Huron, OH8.050$250,000
May 255:00 PM CDTEF1Des Moines, IA3.650$50,000
May 255:14 PM CDTEF0Butler, MO0.740
May 256:14 PM EDTEF0Hardin, OH0.225
May 255:26 PM CDTEF1Bollinger, MO13.0250$30,000
May 256:06 PM CDTEF0McLean, IL0.925$8,000
May 256:09 PM CDTEF1McLean, IL10.375$10,000
May 257:10 PM EDTEF0Montgomery, OH0.125$5,000
May 256:18 PM CDTEF1Cape Girardeau, MO2.1250$20,000
May 256:18 PM CDTEF0St. Francis, AR1.1100
May 256:28 PM CDTEF2Jefferson, IL13.5250$4.0 million
May 256:30 PM CDTEF0Scott, MO0.450$1,000
May 257:30 PM EDTEF0Summit, OH4.250$200,000
May 256:39 PM CDTEF1Union, IL2.0125$150,000
May 256:40 PM CDTEF1Pulaski, IL5.5250$50,000
May 256:45 PM CDTEF1Pulaski, IL10.0120$40,000
May 256:48 PM CDTEF1Crittenden, AR2.5100$500,000
May 256:55 PM CDTEF2Pulaski, IL19.9325$255,000
May 256:58 PM CDTEF0Champaign, IL0.215$5,000
May 257:58 PM EDTEF3Lawrence, IN6.8300$150,000
May 255:08 PM PDTEF1Glenn, CA21.6120$200,000
May 255:12 PM PDTEF1Glenn, CA26.4120$150,000
May 257:18 PM CDTEF1Clay, IL1.075$510,000
May 257:35 PM CDTEF0Richland, IL0.210
May 257:57 PM CDTEF2Crawford, IL5.5200$920,000

All 94 of them

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.