F1 tornado, 山越郡長万部町, Hokkaido, September 25, 2012

Events up to 31 March 2016 are rated on the Fujita scale, which estimates a wind speed from the damage. The Japan Meteorological Agency publishes it in meters a second, over an averaging time that shortens as the scale climbs. Wind speeds and the damage they describe are the Japan Meteorological Agency’s; the averaging time is in brackets. The English wording is ours.

1. F017 to 32 m/s (about a 15-second mean)

   Weak structures such as television aerials are knocked over. Small branches break and shallow-rooted trees lean. A building other than a house may be damaged.

2. F133 to 49 m/s (about a 10-second mean)this tornado

   Roof tiles fly and window glass breaks. Plastic greenhouses are badly damaged. Weak-rooted trees fall and strong ones snap at the trunk. A car on the road is blown off it by the crosswind.

3. F250 to 69 m/s (about a 7-second mean)

   Roofs are torn off houses and weak buildings other than houses collapse. Large trees fall or are twisted apart. Cars are blown off the road and trains can be derailed.

4. F370 to 92 m/s (about a 5-second mean)

   Walls are pushed in and houses collapse. Buildings other than houses break up and scatter, steel-framed ones included. Trains are overturned and cars lifted and thrown. Most large forest trees snap or fall, some are pulled out.

5. F493 to 116 m/s (about a 4-second mean)

   Houses break up and scatter, and weak buildings other than houses are blown away without a trace. Steel frames are flattened. Trains are blown away and cars fly tens of meters. Objects of a tonne and more fall out of the sky.

6. F5117 to 142 m/s (about a 3-second mean)

   Houses are blown away leaving nothing, and standing trees are stripped of their bark. Cars and trains are lifted and flown far from where they stood. Objects of several tonnes fall out of nowhere.

7. Below F0

   The survey confirmed a tornado but found damage too slight for the bottom of the scale, so it is recorded as below it rather than as unrated.

8. Unrated

   The survey recorded a tornado but could not put a number on it, most often because nothing it passed carried a rating the scale can be read from.

Rating

F1 on the Fujita scale

Date

September 25, 2012

Time

17:20 JST

Prefecture

Hokkaido

Area (JMA)

Oshima

Municipality, as recorded

山越郡長万部町

Path length

1.1 km (0.7 mi)

Path width

450 m (492 yd)

On the ground

10 minutes

Direction of travel

toward the south (180 degrees)

Speed over the ground

7 km/h

Where it began

On land

Weather situation

Trough

Deaths

0

Injuries

0

Touchdown point

42.458, 140.333

Lift-off point

42.448, 140.331

Record number

2012092501

The Japan Meteorological Agency records buildings rather than money, in the three degrees Japanese disaster reporting uses. The figures are what local authorities gave the survey and may differ from the final tally.

The live radar over the trackThe forecast for Yakumo, 23 km awayEvery 2012 tornado in HokkaidoEvery tornado in HokkaidoWarnings in force in Japan now

4 more were confirmed in Japan that day.

The Japan Meteorological Agency publishes the survey’s findings and not its working, so there is no narrative, no damage-point survey and no warning archive behind this page the way there is on an American tornado’s. What the database records is above, in full.

Ratings are the survey’s, read off the damage rather than measured. Counts rise sharply through the record because what the Japan Meteorological Agency investigated widened twice, in 1991 and in 2007, not because tornadoes became more frequent. The rating scale is above.

Source: Japan Meteorological Agency website.Japan Meteorological Agency, database of tornadoes and other severe local winds.Prepared by WeatherOverTime from the Japan Meteorological Agency’s data: the events were filtered to tornadoes, the coordinates converted from degrees, minutes and seconds, the totals and rankings computed here, and the place names, scale descriptions and every sentence on this page translated or written by us. It is not a publication of the Japan Meteorological Agency.