EF1 tornado, Artois to Orbend, California, May 25, 2011

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 mphthis tornado

   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

EF1

Date

May 25, 2011

Touchdown

5:08 PM PDT (00:08 UTC)

Lifted

6:46 PM PDT (01:46 UTC)

On the ground

98 minutes

Path length

21.6 miles (34.8 km)

Path width

120 yards (110 m)

Deaths

0

Injuries

0

Property damage

$200,000

County

Glenn County

Touchdown point

39.620, -122.162

Lift-off point

39.717, -121.775

Record number

1105251808-01

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 first and northernmost tornado in the outbreak developed east of the town of Artois in Glenn County at approximately 5:08 pm and moved east-northeast, passing south of the town of Chico in Butte County. It caused significant damage to an almond grove in Glenn County and less significant damage to farm implements, roofing materials, and another almond grove across its path. The rating of an EF1 was based upon the uprooting of hundreds of almond trees with a few instances of broken large branches and trunks. The estimated highest wind speed (3 second gust) based upon damage with this tornado is 95 mph. There were no injuries nor fatalities.

The second tornado of the outbreak developed northeast of downtown Willows in Glenn County at approximately 5:12 pm. It moved east-northeast and passed just south of the town of Durham in Butte County. It caused significant damage to almond groves in Butte County, as well as destroyed one out building, damaged an open barn, and caused roofing damage to two other structures. The rating of an EF1 was based upon the uprooting of thousands of almond trees with many instances of broken large branches and trunks and the physical lifting and carrying of several large trees by five to ten feet. The estimated highest wind speed (3 second gust) based upon damage with this tornado is 105 mph. There were no injuries nor fatalities.

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. One was issued for the county at another hour that day.

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 General Thunderstorms Risk. The outlook in force was issued at 19:39 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.

Chico Municipal (CIC), 17 km from the path, in the two hours either side.

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

The Beale AFB radar (KBBX), 35 km away, was scanning. The volume nearest the touchdown began at 00:08 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 2011 tornado in CaliforniaEvery tornado in California since 1950Warnings in force in California nowThe forecast where you are

93 more were confirmed in the United States that day.

All 94 of them

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.