Tropical Storm Vamei
| Tropical storm (JMA scale) | |
|---|---|
| Category 1 typhoon (SSHWS) | |
 Vamei shortly before landfall | |
| Formed | December 26, 2001 |
| Dissipated | December 28, 2001 |
| Highest winds | 10-minute sustained: 85 km/h (50 mph) 1-minute sustained: 140 km/h (85 mph) |
| Lowest pressure | 1006 hPa (mbar); 29.71 inHg |
| Fatalities | 5 direct |
| Damage | $3.6 million (2001 USD) |
| Areas affected | Singapore, Malaysia, Indonesia |
| Part of the 2001 Pacific typhoon season 2001 North Indian Ocean cyclone season | |
Tropical Storm Vamei (international designation: 0126, JTWC designation: 32W, sometimes called Typhoon Vamei; formerly had the alternate name Tropical Storm 05B) was an unusual Pacific tropical cyclone that, at the time, formed closer to the equator than any other tropical cyclone. The last storm of the 2001 Pacific typhoon season, Vamei developed on December 26 at 1.5° N in the South China Sea. It strengthened quickly and became the only tropical cyclone in history to make landfall near Singapore. Vamei rapidly dissipated over Sumatra on December 28, and the remnants eventually re-organized in the North Indian Ocean. Though officially designated as a tropical storm, the intensity of Vamei is disputed; some agencies classify it as a typhoon, based on sustained winds of 140 km/h (85 mph) and the appearance of an eye. The storm brought flooding and landslides to eastern Malaysia, causing $3.6 million in damage (2001 USD, $4.2 million 2007 USD) and five deaths. The typhoon is named after a songbird with white feathers, popular to feeders in Macau;[1] the name was retired after its usage.
Storm history
Tropical storm (39–73 mph, 63–118 km/h)
Category 1 (74–95 mph, 119–153 km/h)
Category 2 (96–110 mph, 154–177 km/h)
Category 3 (111–129 mph, 178–208 km/h)
Category 4 (130–156 mph, 209–251 km/h)
Category 5 (≥157 mph, ≥252 km/h)
Unknown
Extratropical cyclone, remnant low, tropical disturbance, or monsoon depressionOn December 19, a small low-level circulation was located along the northwest coastline of Borneo; at the same time a plume of cold air progressed southward through the South China Sea on the southeastern periphery of a ridge over the Far East. The vortex drifted southwestward, reaching open water by December 21. The motion northerly air surge was deflected after interacting with the circulation, and at the same time a portion of the air surge crossed the equator. The southerly flow turned eastward, then northward, and in combination with the northerly flow it wrapped into the vortex, resulting in rapid development of the low-level circulation a short distance north of the equator.[2] By December 25, an area of scattered convection persisted about 370 km (230 mi) east of Singapore within an area of low wind shear, in association with the low-level circulation. Continuing slowly westward, the convection deepened and organized further,[3] and at 1200 UTC on December 26 the disturbance developed into a tropical depression about 230 km (145 mi) east of Singapore, which is 156 km (97 mi) north of the equator.[4] This was the first recorded occurrence of a tropical cyclone near the equator.[2]
The depression strengthened further and officially attained tropical storm status at 0000 UTC on December 27, based on the analysis by the Japan Meteorological Agency (JMA),[4] though the Joint Typhoon Warning Center (JTWC) unofficially classified it as a tropical storm six hours prior. Shortly thereafter, an eye with a 39 km (24 mi) diameter became apparent on satellite imagery, with its rainbands extending southward to the opposite side of the equator. At 0600 UTC, the JMA first classified the system as Tropical Storm Vamei, about 65 km (40 mi) northeast of Singapore,[3] and the agency estimated the storm attained peak winds of 85 km/h (50 mph) at the same time.[4] However, the JTWC upgraded Vamei to typhoon status with peak winds of 140 km/h (85 mph), based on a United States Navy ship report from within the eye; a second ship reported wind gusts of 195 km/h (120 mph) in the southern portion of the eyewall. The storm was small and compact, with gales extending about 45 km (30 mi) from its center. At about 0830 UTC on December 27, Vamei made landfall about 60 km (35 mi) northeast of Singapore,[3] in the southeastern portion of the Malaysian state of Johor.[5] Initially, the Malaysian Meteorological Department classified the cyclone as a tropical storm,[6] though it was later re-assessed as a typhoon at landfall.[7]
Tropical Storm Vamei weakened quickly as it crossed the extreme southern portion of the Malay Peninsula, and late on December 27 it weakened to tropical depression status before emerging into the Straits of Malacca, based on analysis by the JMA.[4] The JTWC initially maintained it as a minimal tropical storm, though it was downgraded as the center again approached land.[3] Early on December 28, Vamei moved ashore along northeastern Sumatra, and at 0600 UTC the JMA classified the storm as dissipated.[4] However, convection persisted near the circulation over land, believed to have been caused by upper-level diffluence. On December 29, the system reached the southeastern Bay of Bengal, which was initially believed to have been a separate system. However, the JTWC classified as a continuation of Vamei in a post-season re-evaluation, based on analysis of satellite imagery indicating the circulation of Vamei crossed Sumatra without dissipating. Convection re-developed, and late on December 30 the JTWC classified the cyclone as a tropical storm about 390 km (245 mi) west-southwest of the northwestern tip of Sumatra; initially, due to being treated as a separate system, it was classified as Tropical Cyclone 05B. Vamei quickly developed good outflow and organization, though increased wind shear on December 31 rapidly weakened the storm; by late that day, the center was exposed from the deep convection, and Vamei quickly dissipated.[3]
Unusual formation
Vamei formed and reached tropical storm strength at 1.5º N, only 156 km (97 mi) from the equator.[4] This broke the previous record of Typhoon Sarah in the 1956 Pacific typhoon season, which reached tropical storm strength at 2.2º N.[3] Due to a lack of Coriolis effect near the equator, the formation of Vamei was previously considered impossible.[3] However, a study by the Naval Postgraduate School indicated that the probability for a similar equatorial development was at least once every four centuries.[2]
The circulation from which Vamei developed from was a vortex that appears along the northwest coast of Borneo during every winter, which is maintained by the interaction between monsoonal winds and the local topography. Often, the vortex remains near the coastline, and in an analysis of 51 winters, only six reported the vortex as being over the equatorial waters for four days or more. As the area in the South China Sea between Borneo and Singapore is only 665 km (415 mi) wide, a vortex needs to move slowly to develop. A persistent northerly wind surge for more than five days, which is needed to enhance the vortex, is present, on average, nine days each winter. Additionally, the probability for a pre-existing tropical disturbance to develop into a tropical cyclone is between 10–30 percent. Thus, the conditions for the formation of Vamei are believed to occur once every 100–400 years.[2]
The record Vamei set lasted for about three years. In November 2004, Cyclone Agni developed at 0.7º N in the Arabian Sea, about 78 km (48 mi) from the equator.[8]
Preparations and impact
Four days prior to Vamei moving ashore, the Malaysian Meteorological Department (MMD) issued Storm Advisories for potentially areas. Subsequently, the agency issued Stage Red Heavy Rain Warnings, Category 3 Rough Wind Warning, and Rough Sea Warnings.[5] However, few citizens knew of the passage of the rare storm.[9]
Offshore, strong winds from Vamei damaged two U.S. Navy ships in its eyewall.[2] Upon moving ashore, the storm brought storm surge damage to portions of southeastern Malaysia.[10] Vamei brought strong winds and heavy rainfall to Johor, as well as to portions of Melaka, Negeri Sembilan, and Selangor; rainfall reached over 200 mm (8 in) in Senai in Johor. Additionally, monsoonal moisture, influenced by the storm, produced moderate to heavy precipitation across various regions of peninsular Malaysia.[5] The passage of the cyclone resulted in flooding and mudslides, which forced the evacuation of more than 13,195 people in Johor and Pahang states into 69 shelters.[11][12] The rainfall caused a landslide along Gunung Pulai, which killed five people and destroyed four houses. River flooding was also reported, as a result of the precipitation from Vamei as well as previous rainfall. Damage from the flooding was estimated at RM13.7 million (2001 MYR, $3.6 million 2001 USD). About 40 percent of the damage occurred to crops at a farm in Kota Tinggi. Moderate damage was also reported to transportation, as well as to education and health-care facilities. The Malaysian government provided assistance to the affected families for food, clothing, and repairs, totaling up to RM5,000 (2001 MYR, $1,300 2001 USD).[12] Vamei also brought heavy rainfall to Singapore,[13] which caused air traffic disruptions at the Singapore Changi Airport.[14] The passage of the cyclone resulted in many downed trees.[15] Addi
In 2004, the name "Vamei" was retired and replaced with "Peipah".[16]
See also
External links
- Japan Meteorological Agency 2001 Best Track
- Joint Typhoon Warning Center Typhoon Vamei Report
- Gary Padgett: December 2001 Worldwide Tropical Weather Summary
References
- ^ Gary Padgett. "Monthly Global Tropical Cyclone Summary, December 2001". Australian Severe Weather Index.
- ^ a b c d e C.P. Chang, Ching-Hwang Liu, Hung-Chi Kuo (2003). "Typhoon Vamei: An Equatorial Tropical Cyclone Formation". Naval Postgraduate School Department of Meteorology. Retrieved 2008-03-07.
{{cite web}}: CS1 maint: multiple names: authors list (link) - ^ a b c d e f g Gary Padgett (2002). "December 2001 Worldwide Tropical Weather Summary". Retrieved 2008-03-07.
- ^ a b c d e f Japan Meteorological Agency. "Best Track for the 2001 Pacific typhoon season". Retrieved 2008-03-07.
- ^ a b c Malaysian Meteorological Department. "Tropical Storm Vamei causes widespread floods in Johor". Retrieved 2008-03-09.
- ^ New Straits Times (Malaysia) (2006-12-20). "Change Welcomed".
{{cite news}}:|access-date=requires|url=(help) - ^ Leong Chow Peng (2006-11-14). "Typhoon Vamei a unique experience". New Straits Times (Malaysia).
{{cite news}}:|access-date=requires|url=(help) - ^ Gary Padgett (2005). "November 2004 Worldwide Tropical Weather Summary". Retrieved 2008-03-08.
- ^ Zahar A. (2006-05-01). "Get your facts right first". New Straits Times (Malaysia).
{{cite news}}:|access-date=requires|url=(help) - ^ Cheryl Dybas (May 12 2003). "Hurricanes at the Equator: "Impossible Perfect Storm" Observed" (press release). National Science Foundation.
{{cite news}}: Check date values in:|date=(help) - ^ Richard H. Johnson and Chih-Pei Chang (2007). "Winter Vortex: A Quarter-Century and Beyond" (PDF). American Meteorological Society. Retrieved 2008-03-09.
- ^ a b Dr. Mahathir Told (2002-01-08). "Recent Floods Claimed Five Lives and Caused Substantial Damage". Bernama: The Malaysian National News Agency.
{{cite news}}:|access-date=requires|url=(help) - ^ T.Y. Koh and H. Lim (2005). "Verification of a Mesoscale Simulation of Tropical Cyclone Vamei" (PDF). European Geosciences Union. Retrieved 2008-03-09.
- ^ Jack Williams (2004). "Why don't certain areas in Asia, like Singapore, have typhoons, tornadoes or other disastrous weather?". USAToday.com. Retrieved 2008-03-09.
- ^ Tieh-Yong Koh (2005). "What Makes A Typhoon Spin?" (DOC). School of Physical & Mathematical Sciences, Nanyang Technological University. Retrieved 2008-03-09.
- ^ Tropical Cyclone Programme (2008). "Typhoon Committee Operational Manual - Meteorological Component" (PDF). World Meteorological Organization. Retrieved 2008-03-04.