18. Typhoon MA-ON (Rolly/26w)                      Print this Article
>> October 03-10, 2004

Ma-on: contributed by Hong Kong, China, means 'horse saddle', and is also the name of a peak in Hong Kong.


Ma-on formed from a cluster of thunderstorms in the vicinity of Guam on 29 September. After initial erratic movement, this small system first drifted north before turning to a west-northwesterly track. Upon reaching typhoon intensity Ma-on recurved and ultimately became the sixth super typhoon of the year before becoming the worst storm to hit eastern Japan in over ten years. And this only a week after Typhoon Meari had made landfall in that nation.

Storm Origins

Super Typhoon Ma-on stemmed from an area of convection which developed and persisted approximately 70 nm north-northwest of Guam. It was initially mentioned in JTWC's STWO at 0600 UTC 29 September. Multi- spectral satellite imagery revealed a weak LLCC with disorganized and cyclic convection. An upper-level analysis revealed an area of weak shear and moderate diffluence. The potential for development was set at 'poor'. There was little change over the following two days. The potential was raised to 'fair' at 01/2330 UTC after convection increased and became more organized over the centre. However, this was downgraded to 'poor' again in the regular STWO at 02/0600 UTC when convection failed to consolidate around the LLCC. Although shear continued to be weak at high levels, the centre was bounded by stronger shear to the east and northwest. Also, vorticity had weakened and become more linear while diffluence was neutral. Potential remained 'poor' at 03/0600 UTC when the system was located 790 nm east of Manila, Philippines.

Things had improved by 1430 UTC 3 October. A 03/0903 UTC QuikScat pass showed a tighter and better-defined LLCC while enhanced infrared satellite imagery revealed that convection had both increased and consolidated over the centre. Also, at 03/1200 UTC a ship reported winds of 20 kts approximately 300 nm to the south. Based on these events, the development potential was upped to 'fair'. It was then upgraded to 'good' at 03/1900 UTC, and the first warning on Tropical Depression 26W followed at 04/0000 UTC. Six hours later the depression became Tropical Storm Ma-on when both JTWC and JMA upgraded their respective MSWs to 35-kts and 40-kts (10-min avg). However, strengthening temporarily ceased as the system became stationary approximately 650 nm southeast of Okinawa, Japan. At 03/1800 UTC PAGASA started monitoring the system, naming it Rolly upon the storm's crossing the 135th parallel.

Synoptic History

At 0000 UTC 5 October Tropical Storm Ma-on was drifting slowly northward at 3 kts approximately 615 nm southeast of Okinawa. Strengthening resumed at 05/0600 UTC as the storm began to move a little faster towards the north-northeast. At this time the MSW was raised to 45 kts. The small system then turned northward, and was moving north- westward at 6 kts at 05/1800 UTC when the intensity had climbed a bit more to 50 kts. For the near term, Ma-on's movement was being dictated by an intensifying HIGH to the northeast, and this synoptic feature was to push the tropical cyclone primarily west-northwestward for the next 24 hours. Meanwhile, the storm intensified and was upgraded to a 70-kt typhoon at 06/1200 UTC. At this time the centre was located 410 nm southeast of Okinawa, Japan.

At 0000 UTC 7 October Typhoon Ma-on was still tracking west- northwestward with 75-kt winds approximately 320 nm south-southeast of Okinawa. As things stood, Ma-on was moving around the western side of the HIGH located to the northeast, but changes were afoot. A trough exiting the east coast of China was expected to become vertically- oriented, favouring a poleward heading towards Japan. Typhoon Ma-on quickly responded to this synoptic alteration by turning northwestward, then northward before completing recurvature at 07/1800 UTC. During this period, the storm rapidly intensified after forming an eye. The MSW climbed alarmingly to 90 kts at 0600 UTC, to 115 kts at 1200 UTC, and to 125 kts at 1800 UTC.

Ma-on was upgraded to a 140-kt super-typhoon at 0000 UTC 8 October while located approximately 250 nm southeast of Okinawa, Japan. At this time, typhoon-force winds extended outward 35 nm in all quadrants and 40 nm in the southwest quadrant. Gales reached out as far as 120 nm in the southwest quadrant. Ma-on started to accelerate northeastward over the western periphery of the HIGH to the east as it maintained 140-kt winds. However, the eye began to shrink in diameter at 08/0600 UTC and became more ragged in appearance six hours later. In addition, the system was looking less symmetric in microwave imagery with the strongest deep convection located in the southwest quadrant. The MSW started to fall at 08/1800 UTC but Ma-on held on to its super typhoon title at this time.

Ma-on was downgraded to a 115-kt typhoon at 0000 UTC 9 October approximately 290 nm southwest of Tokyo, Japan. It was speeding north- northeastward at 29 kts at this time. Animated water vapour imagery showed that the system was in the early stages of extratropical transition with dry air intrusion in the southwestern quadrant and an elongated cirrus shield to the northeast. Turning northeastward, Ma-on made landfall on the Izu Peninsula, Honshu, Japan, at 09/0700 UTC with a MSW of 90 kts. After coming ashore, Ma-on weakened rapidly and was downgraded to a 50-kt tropical storm at 09/1800 UTC. At this time, the system had completed its transformation into an extratropical system. The remnant system rapidly moved northeastward, then east-northeastward away from eastern Japan before slowing abruptly to around 10 kts roughly 1100 nm southeast of Hokkaido.

All Asian TC agencies except CWB classified Ma-on as a 100-kt (10-min avg) typhoon with JMA estimating a minimum CP of 920 mb. The CWB of Taiwan estimated a peak MSW of 105 kts while PAGASA's maximum intensity of 100 kts was during the period the typhoon was passing through their AOR.

Damages and Casualties

Ma-on was one of the most powerful storms to strike eastern Japan over the last ten years. The typhoon left at least six people dead, and three persons were reported missing. Plane, train and ferry services nation- wide were disrupted, stranding thousands of travellers. More than 378 domestic and international flights and most ferry services along the east coast were cancelled. In central and eastern Japan, railway operators suspended bullet and local train services and roads were closed to traffic. Heavy downpours also disrupted the practice sessions for Formula One's Japanese Grand Prix in Suzuka but the race went ahead as planned. Rescuers on boats plucked dozens of residents from waterlogged homes in Shizuoka Prefecture. Authorities ordered evacuations in Shizuoka, Mie, Wakayama, Nara and Osaka prefectures, and about 1500 people left their homes for public shelters.

Huang Chunliang Report

Following is the report compiled and sent by Huang Chunliang of Fuzhou City, Fujian Province, China. A special thanks to Chunliang for compiling and sending the information. (To convert wind velocity in metres/second (m/s) to knots, divide m/s by 0.51444, or for an approximation, simply double the m/s value.)

{Part I}. Landfall Obs (based on the JMA warnings)

Severe Typhoon 0422 (MA-ON) made landfall over Izu Peninsula, 
Shizuoka Prefecture, around 09/0700 UTC with a MSW of 40 m/s 
and a CP of 950 hPa.

{Part II}. Top-5 Storm Total [06/1500-09/1500Z] Obs

Ranking    Prefecture      Station         Rainfall (mm)
01         Shizuoka        Omaezaki        413
02         Shizuoka        Shimizu         393
03         Kanagawa        Hakone          392
04         Yamanashi       Yamanaka        385
05         Shizuoka        Yugashima       371

{Part III}. Top-5 Daily Rainfall Obs

Ranking    Prefecture      Station         Rainfall (mm)
01         Shizuoka        Omaezaki       *360 [08/1500-09/1500Z]
02         Shizuoka        Shimizu         297 [08/1500-09/1500Z]
03         Shizuoka        Makinohara      267 [08/1500-09/1500Z]
04         Shizuoka        Yugashima       265 [08/1500-09/1500Z]
05         Shizuoka        Shizuoka        262 [08/1500-09/1500Z]

{Part IV}. Top-5 1-hr Rainfall Obs

Ranking    Prefecture        Station           Rainfall (mm)
01         Shizuoka          Omaezaki         *89 [09/0530-09/0630Z]
02         Shizuoka          Yugashima         75 [09/0630-09/0730Z]
03         Tokyo             Tokyo             69 [09/0810-09/0910Z]
04         Chiba             Kamoga            67 [08/1550-08/1650Z]
05         Kanagawa          Hakone            66 [09/0650-09/0750Z]

{Part V}. Top-5 Peak Sustained Wind (10-min avg) Obs

Ranking    Station                                  Peak wind (mps)
01         Ajiro, Shizuoka (WMO47668, Alt 67m)     *39.4 [09/0720Z]
02         Irouzaki, Shizuoka (WMO47666, Alt 55m)   30.2 [09/0650Z]
03         Haneda, Tokyo (JMA44166, Alt 6m)        *29   [09/0830Z]
04         Omaezaki, Shizuoka (WMO47655, Alt 45m)   27.5 [09/0550Z]
05         Ojima, Tokyo (WMO47675, Alt 74m)        *27.0 [09/0740Z]

{Part VI}. Top-5 Peak Gust Obs

Ranking    Station                                  Peak wind (mps)
01         Irouzaki, Shizuoka (WMO47666, Alt 55m)  *67.6 [09/0607Z]
02         Ajiro, Shizuoka (WMO47668, Alt 67m)     *63.3 [09/0713Z]
03         Ojima, Tokyo (WMO47675, Alt 74m)        *51.5 [09/0725Z]
04         Omaezaki, Shizuoka (WMO47655, Alt 45m)   50.0 [09/0547Z]
05         Yokohama, Kanagawa (WMO47670, Alt 39m)   39.9 [09/0822Z]

{Part VII}. Top-5 SLP Obs

Ranking    Station                             Min SLP (hPa)
01         Irouzaki, Shizuoka (WMO47666)       964.0 [09/0644Z]
02         Omaezaki, Shizuoka (WMO47655)       967.1 [09/0559Z]
03         Ajiro, Shizuoka (WMO47668)          974.1 [09/0714Z]
04         Mishima, Shizuoka (WMO47657)        978.9 [09/0653Z]
05         Shizuoka, Shizuoka (WMO47656)       982.0 [09/0627Z]

{Part VIII} References (Japanese versions only)


Note: "*" = record-breaking values for relevant stations.

(Report written by Kevin Boyle with significant contributions by Huang Chunliang)

Source: Gary Padgett's Monthly Tropical Cyclone Summary - October 2004

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