Typhoon Tokage, known in the Philippines asTyphoon Siony, was the deadliesttyphoon to strikeJapan sinceTyphoon Bess in1982. The twenty-third storm to be named using aninternational list of names during the2004 Pacific typhoon season, Tokage was the last of threetyphoons to impactJapan from late-September to mid-October 2004. Typhoon Tokage began as a tropical depression near theNorthern Mariana Islands on October 10. With very warm waters, the system started to undergo arapid deepening phase early on October 13 and reached its peak strength on the 17th. Tokage madelandfall overJapan on October 20, just before becoming extratropical.^[1][2]

Typhoon Tokage (Siony)

Typhoon Tokage near peak intensity on October 16
Meteorological history
Formed	October 12, 2004
Extratropical	October 20, 2004
Dissipated	October 23, 2004
Very strong typhoon
10-minute sustained (JMA)
Highest winds	155 km/h (100 mph)
Lowest pressure	940hPa (mbar); 27.76 inHg
Category 4-equivalent typhoon
1-minute sustained (SSHWS/JTWC)
Highest winds	230 km/h (145 mph)
Lowest pressure	916hPa (mbar); 27.05 inHg
Overall effects
Fatalities	95
Missing	3
Damage	$7.11 billion (2004USD)
Areas affected	Northern Mariana Islands,Ryukyu Islands,Taiwan,Japan
IBTrACS
Part of the2004 Pacific typhoon season

Tokage was the 10th storm to strike Japan in 2004, making 2004 the largest year ever for the number of storms made landfall in Japan.^[3] The record until 2003 was 6 (1990 and1993), but 2004 was 10.^[4]

FromTyphoon Meari andMa-on, theIntertropical Convergence Zone became active since September 28. A large area of convection persisted on October 10. On October 12, the area of convection separated into two systems, with the other one becoming Typhoon Nock-ten, which existed 480 miles east-southeast of Guam within the ITCZ. The system developed into Tropical Depression 27W at late that day, moving in a west-northwesterly at 15 kn about 200 miles east of Guam. On the October 13, the system developed into a tropical storm, and was named Tokage, subsequently moving very close to the islands of Rota and Guam. Typhoon intensity was achieved early on October 14 when centered 970 miles southeast of Okinawa. Later that day, Tokage briefly turned to the west-southwest. The storm's path curved back to a northwesterly heading by the October 15. The storm curled towards the north as a major shortwave over weakened the subtropical ridge and by October 17 Tokage reached its peak intensity of 125 kn/145 mph. Weakening began later that day as the storm turned back to a more northwesterly heading towards Okinawa and Japan. On October 18, Typhoon Tokage was 290 miles south of Kadena Air Base, Okinawa. Recurvature back to the north-northeast towards Japan ensued while the typhoon slowly weakened. Tokage made its closest approach to Okinawa late on October 19 when it was passed just to the south-southeast. The storm turned to the northeast as continued to accelerate as its extratropical transition began. Tokage madelandfall overTosa-Shimizu, near the southern tip of Shikoku, Japan still at typhoon strength.^[2][3] By October 21, the cyclone weakened into a tropical storm 130 nm west ofTokyo, and later that day, the system completed the transition to a nontropical low. The extratropical remains of Tokage moved rapidly northeastward, crossing theInternational Dateline around midday on October 23.

Tokage came ashore over southern or southeasternJapan on 01:35 (UTC) of October 20.^[5] The highest measured wind gust was 142 mph/63.7 m/s at Unzendake, Nagasaki on October 20. The lowest pressure from a land station was 949.4 mb at Okinoerabu, Kagoshima late on October 19. The highest rainfall amount noted in Japan was 550 mm at Fukuharaasahi between late on October 17 and October 21, with 470 mm falling within a 24-hour period.

A total of 18,000 people were forced to evacuate their homes.^[6] Damages of the typhoon reachedJPY771 billion (US$7.11 billion).^[7] A total of 95 deaths were attributed to high winds, flooding and mudslides caused by Tokage, with an additional three people reported missing.^[8]

• Typhoon Mireille
• Typhoon Meari (2004)
• Tropical Storm Etau (2009)
• Typhoon Wipha (2013)
• Typhoon Neoguri (2014)
• 2018 Japan floods – a catastrophic flood event with similar impacts to Tokage

• Digital Typhoon: Typhoon200423 (TOKAGE) -National Institute of Informatics

• JMA Best Track Data of Typhoon Tokage (0423)(in Japanese)
• JMA Best Track Data (Graphics) of Typhoon Tokage (0423)
• JMA Best Track Data (Text)
• JTWC Best Track Data of Typhoon 27W (Tokage)
• 27W.TOKAGE from the U.S. Naval Research Laboratory