Tropical Storm Usagi (2018)

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Severe Tropical Storm Usagi (Samuel)
Severe tropical storm (JMA scale)
Category 2 typhoon (SSHWS)
Usagi 2018-11-24 0332Z.jpg
Severe Tropical Storm Usagi at peak intensity on November 24
FormedNovember 13, 2018
DissipatedNovember 27, 2018
Highest winds10-minute sustained: 110 km/h (70 mph)
1-minute sustained: 165 km/h (105 mph)
Lowest pressure990 hPa (mbar); 29.23 inHg
Fatalities4 total
Damage$40.8 million (2018 USD)
Areas affectedMarshall Islands, Caroline Islands, Philippines, Vietnam
Part of the 2018 Pacific typhoon season

Severe Tropical Storm Usagi, known in the Philippines as Tropical Storm Samuel, was a tropical cyclone that made landfall on Southern Vietnam in late November 2018, causing severe damage around Ho Chi Minh City. The storm formed from a disturbance in the Central Pacific basin on November 3, but did not develop into a tropical storm until almost three weeks later, on November 13. While never considered as a typhoon by the Japan Meteorological Agency (JMA), Usagi underwent rapid intensification and peaked as a Category 2 typhoon on the Saffir–Simpson scale before making its final landfall on Vũng Tàu, Bà Rịa–Vũng Tàu province as a weakening tropical storm on November 25. Usagi caused one death and ₱52.2 million (US$992,000) in damages in the Philippines, most of which came from agriculture. Usagi caused 3 deaths and ₫925 billion (US$39.8 million) in damages in Vietnam.

Meteorological history[]

Map plotting the storm's track and intensity, according to the Saffir–Simpson scale
Map key
Saffir–Simpson scale
  Tropical depression (≤38 mph, ≤62 km/h)
  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
Storm type
▲ Extratropical cyclone / Remnant low / Tropical disturbance / Monsoon depression

On November 3, the Central Pacific Hurricane Center began monitoring a disturbance that had formed in the Central Pacific basin.[1] Without further development on November 6, the disturbance moved out of the basin and into the West Pacific,[2] where the system was first monitored by the Joint Typhoon Warning Center (JTWC) at 22:00 UTC, assessing its potential of developing into a tropical cyclone within the next 24 hours as low. The system was within favorable conditions for development, with low vertical wind shear and sea surface temperatures reaching 28–30 °C (82–86 °F).[3] The system's tropical cyclone development potential within 24 hours was further upgraded to medium by the JTWC as its broad low-level circulation began to consolidate; however, atmospheric convection was disorganized.[4] On November 9, at 01:30 UTC, the JTWC issued a Tropical Cyclone Formation Alert (TCFA) for the system and upgraded the system's tropical cyclone development potential within 24 hours to high.[5] By the next day, however, the low-level circulation became almost fully exposed as wind shear of 15–25 knots (28–46 km/h; 17–29 mph) displaced the system's convection towards the east, prompting the JTWC to cancel the TCFA and downgrade the system's tropical cyclone development potential within 24 hours to medium.[6] On November 11, the JTWC further lowered the system's tropical cyclone development potential within 24 hours to low as the system's low-level circulation became fully exposed and ill-defined.[7]

On November 13, at 00:00 UTC, the Japan Meteorological Agency (JMA) assessed that the system had developed into a tropical depression near the Marshall Islands.[nb 1] Continuing westwards,[9] wind shear decreased, with the JTWC upgrading the system's tropical cyclone development potential within 24 hours to medium on November 14.[10] The PAGASA began monitoring the system,[11] and on November 17, at 12:00 UTC, the JTWC upgraded the system to a tropical depression, assigning it the designation 33W.[12] Despite dry air surrounding the system, convective activity continued alongside anticyclonic outflow.[13] On November 18, at 03:00 UTC, 33W entered the Philippine Area of Responsibility and was assigned the local name Samuel by the PAGASA.[11] Turning northwest, the system's low-level circulation was broad,[14] ill-defined, and elongated,[15] with wind shear at 25–30 knots (46–56 km/h; 29–35 mph) displacing convection over 100 nautical miles (190 km; 120 mi) to the west of the low-level circulation.[16] 33W made landfall on Hernani, Eastern Samar on November 20, at 17:00 UTC,[11] with the JTWC downgrading it to a disturbance an hour later[12] as the system's convection fragmented.[17] After turning west-southwestward, 33W made 4 more landfalls over Cebu, Negros Occidental, and Iloilo between 22:00 UTC and 02:00 UTC on the next day. Now in the Sulu Sea,[11] the system's low-level circulation moved closer to convection,[18] and on November 21, at 12:00 UTC, the JTWC upgraded 33W back to a tropical depression.[12] 33W made landfall on Araceli, Palawan at 13:00 UTC and moved into the South China Sea afterwards.[11]

On November 22, at 00:00 UTC, both the JMA and the JTWC upgraded 33W to a tropical storm as deep convection covered the system's low-level circulation, with the former assigning it the name Usagi.[9][12][19] Now in a favorable environment with low wind shear, the system's low-level circulation slowly consolidated and became better defined despite still being partially exposed.[20] Usagi exited the Philippine Area of Responsibility at 10:00 UTC;[11] it continued consolidating as rainbands wrapped into the system's center.[21] On November 23, an eye appeared on SSMIS microwave imagery,[22] and at 06:00 UTC, the JMA upgraded Usagi to a severe tropical storm.[9] The JTWC upgraded Usagi to a typhoon later that day.[12] On November 24, at 00:00 UTC, both the JMA and the JTWC estimated Usagi to have peaked, with the JMA estimating maximum 10-minute sustained winds of 110 kilometres per hour (70 mph) alongside a minimum central pressure of 990 hPa (29.23 inHg) and the JTWC estimating maximum 1-minute sustained winds of 165 kilometres per hour (105 mph).[9][12] An eye briefly appeared on satellite imagery before becoming filled with clouds.[23] Later in the day, a combination of land interaction and unfavorable environmental conditions caused Usagi to weaken[11] as its convective structure deteriorated.[24] Rainbands collapsed[25] as the system turned northwest,[11] and by November 25, both the JMA and the JTWC had downgraded Usagi to a tropical storm[9][12] as central convection weakened.[26] Usagi made landfall on Vũng Tàu at 07:00 UTC,[11] with the JTWC downgrading Usagi to a tropical depression later that day.[12] During November 26, the JMA also downgraded Usagi to a tropical depression[9] as the JTWC further downgraded Usagi to a disturbance.[12] Usagi dissipated over Cambodia at 00:00 UTC on November 27.[9]

Preparations and impacts[]

Cloudy skies in Cần Thơ on November 24

Philippines[]

In preparation for the storm, the PAGASA raised signal #1 warnings in Visayas and Mindanao.[27] People and fishermen were advised to not set sail due to rough waves originating from the storm.

Flooding was reported in Iloilo City, with over 7,800 passengers being stranded throughout various ports throughout the country.[28][29] 14 flights were also cancelled due to bad weather caused by the storm.[30] Usagi caused one death in the Philippines,[31] with agricultural damages being estimated at ₱52.2 million (US$992,000).[30] 124,226 people were affected, 21,224 people were displaced, and 2,746 houses were damaged.[32] Several landslides were reported during the storm's passage, all of which were in the island of Samar.[28][30] Basco recorded a gust of 18 metres per second (65 km/h; 40 mph), with Cuyo recording 291.4 millimetres (11.47 in) of rain in 24 hours and 314 millimetres (12.4 in) of rain in total.[11]

Highest Tropical Cyclone Wind Signal Raised[11]
Signal No. Places Raised
1 Agusan del Norte, Agusan del Sur, Aklan, Antique, Biliran, Bohol, Camiguin, Capiz, Cebu, Dinagat Islands, Eastern Samar, Iloilo, Guimaras, Leyte, Masbate, Misamis Oriental, Negros Occidental, Negros Oriental, Northern Samar, southern Occidental Mindoro, southern Oriental Mindoro, Palawan, Romblon, Samar, Siquijor, Southern Leyte, Surigao del Norte, Surigao del Sur

Vietnam[]

88,787 people were mobilized to aid in the storm response.[33] Classes in Ho Chi Minh City were suspended on November 26, with Cần Giờ District suspending classes until November 27.[34] A heavy rain warning was issued for the Central Highlands and the provinces between Bình Thuận and Thừa Thiên Huế. A flood warning was also issued for the Central Highlands, the Southeast, and the provinces between Quảng Trị and Bình Thuận.[35]

Tân Bình District recorded 407.6 millimetres (16.05 in) of rain, surpassing the district's record of most rainfall. 60 roads were flooded in Ho Chi Minh City;[36][37] three people were killed.[38] Flooding on some roads reached 1 metre (3.3 ft) deep. 14 fishermen were rescued; losses from damaged lobster, shrimp, and fish farms were estimated at ₫12 billion (US$516,000).[34] A 300 metres (980 ft) stretch of the North–South railway was washed away in  [vi].[39] 300 families on the island of were stranded after the bridge connecting the island to the mainland washed away.[40] 46 ships sunk as a result of the storm,[41] with 42 square kilometres (16 sq mi) of crops being flooded.[42] 51 houses were damaged,[43] with 160,000 thousand people being evacuated.[44] Losses in Vietnam were estimated at ₫925 billion (US$39.8 million).[45]

See also[]

Notes[]

  1. ^ The JMA is the official Regional Specialized Meteorological Centre for the northwestern Pacific Ocean.[8]

References[]

  1. ^ Foster, Matthew (November 2, 2018). "Two-Day Graphical Tropical Weather Outlook". Central Pacific Hurricane Center. Honolulu, Hawaii. Archived from the original on November 24, 2018. Retrieved November 24, 2018.
  2. ^ Kino, Genki (November 6, 2018). "Two-Day Graphical Tropical Weather Outlook". Central Pacific Hurricane Center. Honolulu, Hawaii. Archived from the original on November 24, 2018. Retrieved November 24, 2018.
  3. ^ "Significant Tropical Weather Advisory for the Western and South Pacific Oceans Reissued from 062200Z-070600Z November 2018". Joint Typhoon Warning Center. November 6, 2018. Archived from the original on November 6, 2018. Retrieved July 9, 2021.
  4. ^ "Significant Tropical Weather Advisory for the Western and South Pacific Oceans from 080600Z-090600Z November 2018". Joint Typhoon Warning Center. November 8, 2018. Archived from the original on November 8, 2018. Retrieved July 9, 2021.
  5. ^ "Tropical Cyclone Formation Alert 090130". Joint Typhoon Warning Center. November 9, 2018. Archived from the original on November 9, 2018. Retrieved July 9, 2021.
  6. ^ "Significant Tropical Weather Advisory for the Western and South Pacific Oceans from 100600Z-110600Z November 2018". Joint Typhoon Warning Center. November 10, 2018. Archived from the original on November 10, 2018. Retrieved July 9, 2021.
  7. ^ "Significant Tropical Weather Advisory for the Western and South Pacific Oceans from 110600Z-120600Z November 2018". Joint Typhoon Warning Center. November 11, 2018. Archived from the original on November 11, 2018. Retrieved July 9, 2021.
  8. ^ Annual Report on Activities of the RSMC Tokyo – Typhoon Center 2000 (PDF) (Report). Japan Meteorological Agency. July 2001. p. 3. Retrieved July 14, 2021.
  9. ^ a b c d e f g Annual Report on the Activities of the RSMC Tokyo - Typhoon Center 2018 (PDF) (Report). Japan Meteorological Agency. December 26, 2019. Archived (PDF) from the original on February 15, 2020. Retrieved July 9, 2021.
  10. ^ "Significant Tropical Weather Advisory for the Western and South Pacific Oceans Reissued from 142000Z-150600Z November 2018". Joint Typhoon Warning Center. November 14, 2018. Archived from the original on November 14, 2018. Retrieved July 9, 2021.
  11. ^ a b c d e f g h i j k Duran, Samuel F.; Galang, Juanito S.; Gile, Robb P.; Reyes, Sheilla Mae R.; Tolentino, Jerome T. (June 2020). DOST-PAGASA Annual Report on Philippine Tropical Cyclones (PDF) (Report). Quezon City, Philippines: PAGASA. ISSN 2672-3190. Retrieved July 9, 2021.
  12. ^ a b c d e f g h i "2018 Western North Pacific Best Track Data". Joint Typhoon Warning Center. Retrieved July 9, 2021.
  13. ^ "RSMC Tropical Cyclone Prognostic Reasoning No. 2 for TD Located at 6.6N 135.5E". Japan Meteorological Agency. November 18, 2018. Archived from the original on November 18, 2018. Retrieved July 9, 2021.
  14. ^ "Prognostic Reasoning for Tropical Depression 33W (Thirtythree) Warning NR 01". Joint Typhoon Warning Center. November 18, 2018. Archived from the original on November 18, 2018. Retrieved July 12, 2021.
  15. ^ "Prognostic Reasoning for Tropical Depression 33W (Thirtythree) Warning NR 02". Joint Typhoon Warning Center. November 18, 2018. Archived from the original on November 18, 2018. Retrieved July 12, 2021.
  16. ^ "Prognostic Reasoning for Tropical Depression 33W (Thirtythree) Warning NR 04". Joint Typhoon Warning Center. November 19, 2018. Archived from the original on November 19, 2018. Retrieved July 12, 2021.
  17. ^ "Prognostic Reasoning for Tropical Depression 33W (Thirtythree) Warning NR 11". Joint Typhoon Warning Center. November 20, 2018. Archived from the original on November 21, 2018. Retrieved July 12, 2021.
  18. ^ "Prognostic Reasoning for Tropical Depression 33W (Thirtythree) Warning NR 13". Joint Typhoon Warning Center. November 21, 2018. Archived from the original on November 21, 2018. Retrieved July 14, 2021.
  19. ^ "Prognostic Reasoning for Tropical Depression 33W (Thirtythree) Warning NR 16". Joint Typhoon Warning Center. November 22, 2018. Archived from the original on November 22, 2018. Retrieved July 14, 2021.
  20. ^ "Prognostic Reasoning for Tropical Depression 33W (Thirtythree) Warning NR 17". Joint Typhoon Warning Center. November 22, 2018. Archived from the original on November 22, 2018. Retrieved July 22, 2021.
  21. ^ "Prognostic Reasoning for Tropical Storm 33W (Usagi) Warning NR 19". Joint Typhoon Warning Center. November 22, 2018. Archived from the original on November 22, 2018. Retrieved July 22, 2021.
  22. ^ "RSMC Tropical Cyclone Prognostic Reasoning No.22 for STS 1829 Usagi (1829)". Japan Meteorological Agency. November 23, 2018. Archived from the original on November 23, 2018. Retrieved July 22, 2021.
  23. ^ "Prognostic Reasoning for Typhoon 33W (Usagi) Warning NR 25". Joint Typhoon Warning Center. November 24, 2018. Archived from the original on November 24, 2018. Retrieved July 26, 2021.
  24. ^ "Prognostic Reasoning for Typhoon 33W (Usagi) Warning NR 26". Joint Typhoon Warning Center. November 24, 2018. Archived from the original on November 24, 2018. Retrieved July 26, 2021.
  25. ^ "Prognostic Reasoning for Typhoon 33W (Usagi) Warning NR 27". Joint Typhoon Warning Center. November 24, 2018. Archived from the original on November 24, 2018. Retrieved July 26, 2021.
  26. ^ "Prognostic Reasoning for Tropical Storm 33W (Usagi) Warning NR 28". Joint Typhoon Warning Center. November 25, 2018. Archived from the original on November 25, 2018. Retrieved July 26, 2021.
  27. ^ "Samuel, napanatili ang lakas bago ang inaasahang landfall". ABS-CBN News and Current Affairs (in Tagalog). November 20, 2018. Retrieved February 22, 2021.
  28. ^ a b "Bagyong Samuel, nagdulot ng pagbaha sa Visayas". ABS-CBN News and Current Affairs (in Tagalog). November 21, 2018. Retrieved February 22, 2021.
  29. ^ "Over 7,800 stranded at seaports due to Tropical Depression Samuel". Rappler. Retrieved February 22, 2021.
  30. ^ a b c "Situational Report No.11 for Preparedness Measures and Effects of TD SAMUEL" (PDF). National Disaster Risk Reduction and Management Council. November 24, 2018. Retrieved November 25, 2018.
  31. ^ Amazona, Roel (November 22, 2018). "1 dead, thousands displaced as 'Samuel' cuts through Samar". Philippine News Agency. Retrieved November 22, 2018.
  32. ^ DSWD DROMIC Terminal Report on Tropical Depression "Samuel" (Report). Department of Social Welfare and Development Disaster Response Operations Monitoring and Information Center. January 22, 2019. Retrieved July 27, 2021.
  33. ^ "Lực lượng Hải quân tập trung giúp dân ứng phó bão số 9". Báo Tài nguyên và Môi trường (in Vietnamese). Ministry of Natural Resources and Environment. November 25, 2018. Retrieved July 27, 2021.
  34. ^ a b "Bão số 9 đổ bộ đất liền Nam Bộ, suy yếu thành áp thấp nhiệt ��ới".  [vi] (in Vietnamese). November 26, 2018. Retrieved July 27, 2021.
  35. ^ "Bão số 9 tiếp tục mạnh lên giật cấp 12, biển động mạnh sóng cao 6 mét".  [vi] (in Vietnamese). November 23, 2018. Retrieved July 27, 2021.
  36. ^ "Vì sao bão số 9 gây mưa lớn kỷ lục khiến Sài Gòn ngập khắp nơi?". VietNamNet (in Vietnamese). November 26, 2018. Retrieved July 27, 2021.
  37. ^ Nguyen, Huu (November 26, 2018). "Storm Usagi disrupts air traffic in Saigon". VnExpress. Retrieved July 31, 2021.
  38. ^ "TP HCM 3 người chết do ảnh hưởng bão số 9".  [vi]. November 27, 2018. Retrieved July 9, 2021.
  39. ^ "Thông tuyến đường sắt Bắc - Nam sau tàn phá của bão số 9". Voice of Vietnam (in Vietnamese). November 26, 2018. Retrieved July 27, 2021.
  40. ^ Nghia, Cong; Nguyen, Tri (November 27, 2018). "Usagi flooding wipes bridge out, trapping residents on island". VnExpress. Retrieved July 31, 2021.
  41. ^ "Hậu quả bão số 9 - Usagi". Radio Free Asia (in Vietnamese). November 26, 2018. Retrieved July 27, 2021.
  42. ^ "Ngập lụt đe dọa các tỉnh miền Trung".  [vi] (in Vietnamese). November 27, 2018. Retrieved July 27, 2021.
  43. ^ "ECHO Daily Flash of 26 November 2018". Directorate-General for European Civil Protection and Humanitarian Aid Operations Emergency Response Coordination Centre. November 26, 2018. Retrieved July 27, 2021.
  44. ^ "Asia and the Pacific: Weekly Regional Humanitarian Snapshot (20 - 26 November 2018)". United Nations Office for the Coordination of Humanitarian Affairs. November 26, 2018. Retrieved July 27, 2021 – via ReliefWeb.
  45. ^ "Tóm tắt các cơn bão trong năm 2018" (in Vietnamese). Government of Tuyen Quang province. January 5, 2019. Archived from the original on July 8, 2021. Retrieved January 20, 2019.
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