Rananim: contributed by the Federated States of Micronesia, is the Chuukese word for 'hello.'
Typhoon Rananim was the first of two tropical cyclones to strike China during the month of August and became the worst storm to affect that nation since Typhoon Winnie (1997).
At 0600 UTC on 5 August JTWC issued a STWO for a persistent area of deep convection located approximately 380 nm west-northwest of Guam. Multi-spectral imagery and a QuikScat pass revealed a possible weak LLCC with isolated, disorganized convection. Upper-level analysis indicated that the suspect area was located in a region of weak to moderate wind shear and moderate diffluence. The potential for development of a significant tropical cyclone within the next 24 hours was poor. The LLCC consolidated on the 6th and the deep convection became more persistent and better organized. Based on this, JTWC upgraded the potential to fair. This was superceded by a TCFA at 06/2100 UTC. At this time the disturbance was relocated to a position 560 nm east of Manila in the Philippines. A second relocation was required six hours later, placing the centre nearly a degree south near 14.6N/130.7E. Warnings began on Tropical Depression 16W at 07/1800 UTC with the system moving northward at 10 kts approximately 590 nm south of Okinawa, Japan.
At 0000 UTC 8 August, the poorly-defined centre of Tropical Depression 16W was continuing northward along the northwestern periphery of the near-equatorial ridge. A TUTT was located between that HIGH and the subtropical ridge, and the prognostic reasoning issued at the time indicated that after 24 hours the TUTT would move east, allowing the two ridges to combine. This synoptic situation would result in a north to northeast heading for the depression. QuikScat imagery indicated only weak winds associated with the LLCC with the strongest winds to the southwest. At 08/0600 UTC multi-spectral imagery indicated cycling convection over the broad centre and also several weak low-level vortices rotating around the main area of convection. The name Rananim was assigned when JMA upgraded the system to a tropical storm at 08/1200 UTC. JTWC also promoted TD-16W to tropical storm intensity at this time, setting the MSW at 35 kts. Turning northeastward at 08/1800 UTC Rananim strengthened a little to 40 kts with a recent TRMM pass showing a sheared LLCC on the eastern edge of the deep convection.
Tropical Storm Rananim reverted back to its northward motion at 0000 UTC on 9 August, moving to a position 440 nm south-southeast of Okinawa, Japan. At this time both QuikScat and microwave imagery showed a well- defined LLCC which still lay on the eastern side of the deep convection. The MSW increased during the day from 45 kts at 09/0000 UTC to 55 kts at 09/1800 UTC. The forward motion slowed for a time as Rananim turned west-northwestward before picking up again to around 7-8 kts. As the 10th dawned, Rananim was close to typhoon strength. The storm had turned towards the northwest and was located 290 nm south of Okinawa. Deep convection had increased by this time in the northern semicircle while the poleward outflow pattern had also improved. The MSW reached 65 kts at 10/1200 UTC as the newly-upgraded typhoon continued northwestward along the western periphery of the mid-level steering ridge to the northeast.
By 0000 UTC on 11 August Typhoon Rananim had closed to within 195 nm south-southwest of Okinawa, its strengthening phase bringing the MSW up to 75 kts. Intensification continued, and satellite imagery showed the development of a small, ragged eye at 11/0600 UTC. After the intensity had reached 85 kts Rananim began to weaken slightly as the outflow became more restricted, but intensification soon resumed again and the storm reached its peak intensity of 90 kts at 12/0000 UTC as it began to approach the Chinese coast.
At 0000 UTC on 12 August Rananim was moving north-northwestward approximately 150 nm northeast of Taipei, Taiwan, at its peak intensity of 90 kts. This was maintained as the storm passed north of the island, its track altering to a west-northwesterly heading. This track ultimately carried the cyclone inland at approximately 12/1300 UTC near Wenling, Zhejiang Province, China. As Typhoon Rananim crossed the Chinese coast it began to weaken. By the time the 1800 UTC warning was issued the MSW had fallen to 70 kts. Further weakening occurred as the storm progressed farther west into China. JTWC downgraded Rananim to a 60-kt tropical storm in their final warning at 13/0000 UTC, and JMA issued their final warning on the system as a 30-kt tropical depression at 13/0600 UTC. (See Section E below for more information on the inland progress of the weakening depression.)
Editor's Note: JMA's peak 10-min avg MSW for Rananim was 80 kts, and this was also the peak intensity estimated by the Central Weather Bureau of Taiwan. However, HKO assigned a peak MSW of 85 kts, and NMCC estimated Rananim's peak 10-min avg MSW at 90 kts--equivalent to a 1-min avg MSW of 105 kts. Thus, NMCC and HKO considered Rananim a more intense typhoon than did JTWC. PAGASA named this system Karen, and estimated the peak intensity of Typhoon Karen at 75 kts during the time it was within that agency's AOR. The cyclone had exited PAGASA's AOR by 11/1800 UTC, shortly before reaching its overall peak intensity. The minimum CP estimated by JMA was 950 mb. At Rananim's peak intensity, gales covered a zone 220 nm in diameter. (Rather nostalgic having a typhoon named Karen in the NWP again, even if only an unofficial name. Typhoon Karen of November, 1962, was one of the fiercest and most famous typhoons to strike the island of Guam in modern times.)
The observations in this section were compiled and sent by Huang Chunliang from data obtained at the following URL:
(1) Wind and Pressure Observations (all dates 11 September) =========================================================== Station Min SLP (hPa) Peak Sust Wind (kts) Peak Gust (kts) ----------------------------------------------------------------------- Miyakojima 952.9 (1236 UTC) 50.9 (1050 UTC) 94.9 (1110 UTC) Ishigakijima 975.3 (1410 UTC) 51.9 (2030 UTC) 82.0 (0721 UTC) Iriomotejima 978.7 (1656 UTC) 46.1 (2030 UTC) 70.2 (2022 UTC) Yonagunijima 983.5 (1618 UTC) 39.8 (1630 UTC) 68.6 (1618 UTC) (2) Rainfall Measurements ========================= Station WMO Number Alt (m) Storm Total (mm) Period (UTC) --------------------------------------------------------------------- Miyakojima 47927 40 229.0 (*) 09/1500 - 12/1500 Ishigakijima 47918 6 160.0 (#) 09/1500 - 12/1500 Iriomotejima 47917 9 146.5 09/1500 - 12/1500 Yonagunijima 47912 30 165.5 09/1500 - 12/1500 Notes: (*) - 188.0 mm out of the total fell during the 24-hour period ending at 12/0000 UTC (#) - 138.5 mm out of the total fell during the 24-hour period ending at 12/0000 UTC
(1) Landfall Observations
According to the NMCC warnings, Typhoon 0414 (Rananim) made landfall in Shitang Town, Wenling City (a sub-city of Taizhou City), Zhejiang Province around 12/1200 UTC with a MSW of 87 kts and a CP of 950 hPa. Interestingly, the town of Shitang was exactly the place which saw the first sunbeam of the new century in Mainland China on January 1, 2000.
After rampaging through southern Taizhou City, northern Wenzhou City, northern Lishui City and Quzhou City, Rananim eventually departed from Zhejiang Province and entered Jiangxi Province as a tropical storm around 13/0300 UTC. The storm didn't finish its 22-hour journey in northern Jiangxi Province until 14/0100 UTC, by which time it had weakened to a depression.
Tropical Depression Rananim then moved through southeastern Hubei Province and northeastern Hunan Province, where it finally dissipated as a significant tropical cyclone.
(2) Rainfall Observations
(a) Zhejiang Province
During the 72-hour period ending at 14/0000 UTC, rains > 200 mm were recorded at 35 weather stations, among which 14 stations reported rains > 300 mm with Shabu (located in Huangyan District, Taizhou City), Zhuxi (located in Xianju County, Taizhou City) and Wugen (located in Wenling City--a sub-city of Taizhou City) ranking the top three and reporting 454 mm, 453 mm and 436 mm, respectively. However, it should be noted that it was a hydrological station that reported the most torrential rain during the typhoon--Futou, Yueqing City (a sub-city of Wenzhou City) recorded a 24-hour accumulation of 703.5 mm, which turned out to be a new record for Zhejiang Province's daily rainfall amounts.
(b) Jiangxi Province
During the 60-hour period ending at 15/0000 UTC, rains > 100 mm were recorded in 39 counties/cities, among which Lushan, Yongxiu, Xinjian, Jinxian, Dongxiang, Fengcheng and Yujiang reported rains > 200 mm with Lushan reporting the highest amount of 268 mm (200 mm out of this total fell during the 24-hour period ending at 14/0000 UTC).
(c) Hunan Province
Rains > 100 mm were recorded at 9 stations during the 24-hour period ending at 15/0000 UTC with Qiyang County reporting the highest amount of 120.6 mm.
(d) Taiwan Region
Neuchusan, Hsinchu County, reported the highest storm total of 345 mm during the 35-hour period ending at 12/0300 UTC.
(e) Other Provinces
Some of the stations located in Fujian, Hubei, Henan, Anhui and Jiangsu also reported torrential rains during the typhoon.
(3) Wind Observations
Typhoon-force winds were reported in the coastal region of Zhejiang Province with gusts exceeding 78 kts being recorded by 11 stations, among which Dachen Dao (WMO 58666, 28.45E/121.88, Alt 84 m) reported the highest gusts, topping 114.1 kts--a new record for the station--at 12/0721 UTC. Other significant gust observations include: Shamen, Wenling City--104.0 kts, and Sanjiaotang, Sanmen County--90.2 kts.
Most areas of Shanghai Municipality reported peak gusts of Beaufort Force 7 to 9 during the storm.
Over 18,000,000 residents in Mainland China were affected by the typhoon. Official statistics indicated that Typhoon Rananim had killed 168 people and caused 20.1 billion yuan of direct economic losses in the mainland.
Additional articles on the effects of Typhoon Rananim in China may be found at the following URL:
The China Meteorological Administration (CMA) has evaluated Typhoon Rananim (NMC 0414) as the strongest landfalling typhoon for the Chinese Mainland since Typhoon Sally (NMC 9615) made landfall in Wuchuan, Guangdong Province on September 9, 1996, and the most intense for Zhejiang Province since Typhoon Wanda (no number was assigned by NMC, which did not begin to number tropical storms until 1959) made landfall in Xiangshan, Zhejiang Province on August 1, 1956.
(Report written by Kevin Boyle with significant contributions by Huang Chunliang)
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