F1 tornado, Madera Muni Arpt, California, May 20, 2002

1. F040 to 72 mph

   Light damage. Surface peeled off some roofs, gutters and siding damaged, branches broken, shallow-rooted trees pushed over.

2. F173 to 112 mphthis tornado

   Moderate damage. Roofs badly stripped, mobile homes overturned or badly damaged, exterior doors lost, windows broken.

3. F2113 to 157 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. F3158 to 206 mph

   Severe damage. Whole stories of well-built houses destroyed, large buildings badly damaged, trains overturned, trees debarked, heavy cars lifted and thrown.

5. F4207 to 260 mph

   Devastating damage. Well-built houses leveled, structures with weak foundations moved some distance, cars thrown and large missiles generated.

6. F5261 to 318 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

F1

Date

May 20, 2002

Touchdown

3:59 PM PDT (22:59 UTC)

Path length

2.7 miles (4.3 km)

Path width

40 yards (37 m)

Deaths

0

Injuries

0

Property damage

$130,000

County

Madera County

Touchdown point

36.930, -120.120

Lift-off point

36.930, -120.050

Record number

98

The thunderstorm that supported a tornado at approximately 1500 PST also brought very large hail and locally heavy rain to areas to the north and north-northeast of Madera and the tornado track area.

This tornado occurred from the explosive development of a cell along neighboring cells' outflow boundary convergence. The tornado track on the ground was 2.675 miles and mostly F0 in intensity and as wide as 100 yards. It began relatively weak, peeling roofs off from farm structures, downing trees and fencing, but engulfing a well-built structure with minimal damage. However, a 1/4-mile stretch reached F1 intensity as it totally demolished a small farm structure toward the end of its run and was narrowed to a 40-yard path width at that point. The tornado occurred essentially in a rural area of south Madera, tracked west-to-east, but finished with a sweep toward the southeast.

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 19:54 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.

The San Joaquin Valley radar (KHNX), 80 km away, was scanning. The volume nearest the touchdown began at 23:00 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.

The live radar over the trackEvery 2002 tornado in CaliforniaEvery tornado in California since 1950Warnings in force in California nowThe forecast where you are

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.