Tropical Storm Agnes (1978)

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Agnes was one of the few tropical cyclones that formed in the South China Sea and intensified into a severe tropical storm. According to the Royal Hong Kong Observatory's tropical cyclone annual report, a low-pressure area formed in the northern South China Sea on July 22. Two days later, in the afternoon, satellite imagery analysis by the Observatory indicated that this low-pressure area had developed into a tropical depression  [ zh ], located approximately 570 km south of Hong Kong, moving northward at about 16 km/h toward southern China. [1] The U.S. Joint Typhoon Warning Center assessed that the tropical depression strengthened into a tropical storm on the afternoon of July 25 southwest of the Pratas Islands, naming it Agnes. [2] The Royal Hong Kong Observatory followed suit on the same day, [1] and Taiwan's Central Weather Administration upgraded it to a minimal typhoon  [ zh ] on the same date. [3] [Note 1] [4]

Late on July 25, Agnes moved to the sea off Shanwei, continuing to intensify. Initially, the subtropical ridge in the western Pacific was positioned eastward, with its western ridge point around 120°E, allowing Agnes to move northward toward southern China. By July 26–27, the ridge extended westward to around 115°E, and Agnes, influenced by easterly airflow south of the ridge, turned westward, moving slowly along the southern Chinese coast toward the east of the Leizhou Peninsula. [5] As it moved west, Agnes's circulation continued to organize. On the morning of July 26, the Royal Hong Kong Observatory upgraded it to a severe tropical storm. During the day, it passed near the Pearl River Estuary, affecting the area. By evening, Agnes nearly stalled south of Hong Kong, then resumed a slow westward movement, gradually moving away from Hong Kong toward the south of Shangchuan Island and continuing toward the Leizhou Peninsula. [1]

As Typhoon Wendy entered the Pacific near the Ryukyu Islands later on July 27, Agnes was affected by Wendy's broad circulation, triggering the Fujiwhara effect. This caused Agnes to slow down and nearly stall again. [1] [6] Simultaneously, the subtropical ridge retreated eastward significantly within a short period, with its western ridge point moving to around 130°E by July 29. [5] Combined with these factors, Agnes began to alter its path on July 28, looping counterclockwise east of the Leizhou Peninsula before moving eastward at 8 km/h, approaching the Pearl River Estuary again. [7] On July 29, influenced by the ridge's retreat and southwest airflow related to Wendy, Agnes turned northeast, accelerating to 15 km/h toward areas east of Hong Kong. [5] The Pearl River Estuary experienced storm impacts again that day, with gales and heavy rain. Late that evening, radar observations from the Royal Hong Kong Observatory showed Agnes moving north-northeast, slightly weakening. [1] Agnes made landfall on the coast of Pinghai Town  [ zh ], Huidong County, on the morning of July 30, entering southern China. Due to terrain effects, its structure was severely disrupted, rapidly weakening. On the same day, the Joint Typhoon Warning Center, Hong Kong Observatory, and Central Weather Bureau downgraded it to a tropical depression, and it soon dissipated in eastern Guangdong. [2] [3] [1]

Impact

Hong Kong

China Hong Kong location map.svg
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Tai O
83 km/h
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Cheung Chau
89 km/h
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Green Island
111 km/h
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Kai Tak
67 km/h
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Waglan Island
111 km/h
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Tate's Cairn
109 km/h
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Cape D'Aguilar
78 km/h
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Star Ferry Pier
76 km/h
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Maximum hourly average wind speeds recorded by the Royal Hong Kong Observatory in various locations (data from the first impact). [1] Legend:
Red pog.svg indicates gale
Purple pog.svg indicates storm
China Hong Kong location map.svg
Red pog.svg
Tai O
65 km/h
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Cheung Chau
67 km/h
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Green Island
74 km/h
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Kai Tak
46 km/h
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Waglan Island
85 km/h
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Tate's Cairn
89 km/h
Yellow pog.svg
Cape D'Aguilar
56 km/h
Yellow pog.svg
Star Ferry Pier
57 km/h
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Maximum hourly average wind speeds recorded by the Royal Hong Kong Observatory in various locations (data from the second impact). [1] Legend:
Yellow pog.svg indicates strong wind
Red pog.svg indicates gale
Purple pog.svg indicates storm
  • Local peak intensity classification: Severe tropical storm (HKO)
  • Local maximum sustained wind speed: 110 km/h (31 m/s; 59 kn) (10-minute)
  • Highest local tropical cyclone warning signal: Signal No. 8  [ zh ] (all directions)
  • Closest approach to local area: 3:00 a.m., July 30, 1978 (second impact)
  • Closest position to local area: Approximately 60 km east of Observatory headquarters (second impact)

The Royal Hong Kong Observatory hoisted Signal No. 1  [ zh ] at 7:30 a.m. on July 25. As Agnes strengthened into a tropical storm and approached Hong Kong that afternoon, the Observatory upgraded to Signal No. 3  [ zh ] at 10:50 p.m. [1] The following morning, as Agnes intensified into a severe tropical storm and moved toward the Guangdong coast, winds in Hong Kong strengthened, prompting the Observatory to issue Signal No. 8 Northeast at 9:00 a.m., followed by Signal No. 8 Southeast at 3:45 p.m., which remained in effect for nearly a day. [1] [8] As Agnes moved westward, the Observatory downgraded to Signal No. 3 at 1:30 p.m. on July 27. [1] [9] However, Agnes stalled and showed signs of turning back, posing a continued threat. Signal No. 3 remained in effect for over two days (approximately 52 hours), the second-longest duration on record. [10] [11] The Observatory warned of a possible second approach, urging residents not to let their guard down. [12]

As predicted, influenced by Typhoon Wendy, Agnes approached the Pearl River Estuary again. [13] The Observatory re-issued Signal No. 8 Northeast at 5:25 p.m. on July 29, followed by Signal No. 8 Northwest at 2:30 a.m. and Signal No. 8 Southwest at 4:40 a.m. on July 30. [1] [14] After Agnes made landfall in Huidong County, the Observatory downgraded to Signal No. 3 at 7:10 a.m. and removed all tropical cyclone warnings by 3:10 p.m. on July 30. [1] [15] Agnes's two impacts on the Pearl River Estuary led to warnings from July 25 to July 30, totaling five days—the longest duration since World War II. The Signal No. 8 Southeast was in effect for 21 hours and 45 minutes, a record for that signal until surpassed by Tropical Storm Lionrock's 22 hours in 2021. The issuance of Signal No. 8 for all directions was a unique event since World War II. [10]

Due to Agnes, Hong Kong's sea, land, and air transport were heavily disrupted. All ferries within the harbor and to Macau and Mainland China were suspended, as were the Peak Tram, Hong Kong Tramways, and most bus routes from 3:00 p.m. on July 26. [16] The Kowloon-Canton Railway operated normally. [1] Transport briefly resumed around noon on July 27 as Agnes moved away. [17] However, as Agnes returned to the Pearl River Estuary, transport was disrupted again from July 29. Ferries, buses, and flights were suspended, though the impact was minimal due to it being a weekend, with services gradually resuming the next day. [18] During the storm's two impacts, Kai Tak Airport saw 176 flights canceled, delayed, or diverted. [1]

Overall, Hong Kong's damage was moderate, but prolonged heavy rain persisted. The Observatory recorded 519 mm of rainfall, making Agnes the fifth-highest rainfall-producing tropical cyclone in Hong Kong since 1884, following Tropical Storm Agnes (1965). [19] The extended rainfall severely impacted farmers in the New Territories. The Agriculture, Fisheries and Conservation Department reported that 515 acres (approximately 2.08 km²) of farmland were flooded, particularly in Tai Po District, with vegetable and fruit production expected to drop by half, causing market prices to rise up to fivefold. [20] In San Tin, Ngau Tam Mei, 80% of fishponds overflowed, with tens of thousands of fish washed away, and vegetable fields required a month to recover, leaving no New Territories vegetables available during that period. [21] In urban areas, heavy rain damaged numerous old buildings, with 20 declared dangerous and sealed off, mostly in Central  [ zh ] and Western District  [ zh ]. [22] In Tsuen Wan, the Sha Tsui Road  [ zh ] area saw severe flooding on July 30, with water depths of 0.6 to 1.2 meters. In Chai Wan Kok village, a drainage channel collapsed, sending mud and floodwater into a squatter area, destroying three wooden houses and damaging nearly 40 others, with no injuries reported. [23] The storm caused three deaths and 134 injuries. Two victims, a vegetable vendor couple from Sha Tin, drowned on July 29 when their taxi lost control and fell into a water-filled ditch in Fo Tan. The driver escaped, but the couple did not. [24] Another victim, an elderly woman in Wong Tai Sin's Ma Chai Hang  [ zh ] squatter area, was buried by a landslide. [25]

Macau

In Macau, the Macau Meteorological and Geophysical Bureau hoisted Signal No. 8  [ zh ] at 10:45 a.m. on July 26. The storm led to the cancellation of greyhound racing at the Canidrome, the closure of the Governor Nobre de Carvalho Bridge, suspension of transport services, and halting of ferries between Hong Kong and Macau. [26] The Signal No. 8 was lowered at 5:45 p.m. the next day, with no reported casualties or significant damage, though the bridge remained closed. [27] [28] As the storm approached again, the bureau issued storm warnings and hoisted Signal No. 3  [ zh ] from 5:00 p.m. on July 29, suspending transport and cancelling greyhound racing again. Damage remained minimal, with only one vacant wooden building collapsing. [29] Signal No. 3 was lowered at 6:30 a.m. the next day, and normal activity resumed, though tourist numbers significantly decreased due to the storm. [30]

Mainland China

  • Local peak intensity classification: Typhoon (CMA)
  • Local maximum sustained wind speed: 40 m/s (140 km/h; 78 kn) (2-minute)
  • Local minimum central pressure: 960 hPa (28.35 inHg)

The Guangdong Provincial Meteorological Observatory issued an emergency alert on July 26 for "Typhoon No. 7" (Agnes), noting that it would loop near the Pearl River Estuary or make landfall in central Guangdong within 24 hours, with heavy rain expected in Huiyang, Foshan, and Shantou. [31] As Agnes looped at sea and approached Hong Kong again, the observatory noted on July 29 that the typhoon would likely land between Bao'an County and Huilai County. [32] The typhoon made landfall around 7:00 a.m. on July 30 in Pinghai Town  [ zh ], east of the Pearl River Estuary. Bao'an County recorded 226 mm of torrential rain on the day of landfall, with a total of 440 mm during the storm, the highest among Guangdong counties. [7] No severe damage was reported. [33] Earlier, Guangdong had experienced its worst heatwave and drought since 1834, and Xinhua News Agency reported that the typhoon's arrival temporarily alleviated these conditions. [34]

See also

Notes

  1. ↑ Most regional meteorological centers, including the Japan Meteorological Agency, use 10-minute sustained winds to measure tropical cyclone intensity, but the U.S. Joint Typhoon Warning Center uses 1-minute sustained winds, with a conversion ratio of approximately 1:1.14.

References

  1. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 Meteorological Results: 1978 (PDF) (Report). Hong Kong Royal Observatory. 1979. Archived (PDF) from the original on 2020-09-06. Retrieved 2025-09-03.
  2. 1 2 Joint Typhoon Warning Center; Naval Pacific Meteorology and Oceanography Center (1979). Annual Tropical Cyclone Report: 1978 (PDF) (Report). United States Navy, United States Air Force. Archived (PDF) from the original on 2018-09-25. Retrieved 2025-09-03.
  3. 1 2 "Mínguó liùshíqī nián běi tàipíngyáng xībù táifēng gàishù" 民國六十七年北太平洋西部颱風概述 [Overview of Typhoons in the Western North Pacific in 1967](PDF). Central Weather Bureau (in Chinese). Archived (PDF) from the original on 2020-09-19. Retrieved 2025-09-03.
  4. ↑ Christopher W Landsea; Hurricane Research Division (2004-04-26). "Subject: D4) What does "maximum sustained wind" mean? How does it relate to gusts in tropical cyclones?". Frequently Asked Questions. National Oceanic and Atmospheric Administration's Atlantic Oceanographic and Meteorological Laboratory. Archived from the original on 2009-05-19. Retrieved 2020-07-25.
  5. 1 2 3 孔宁谦 (1980). "Lùjìng qūzhé duō biàn de 7807 hào qiáng táifēng" 路径曲折多变的7807号强台风[The Complex and Variable Path of Typhoon No. 7807]. Guangxi Meteorology (in Chinese) (4): 28–33.
  6. ↑ "Ài nà sī shòu lìng yī gǔ fēngbào yǐngxiǎng bèi xuánwō qìliú xīyǐn qiānzhì zhéfǎn" 愛娜斯受另一股風暴影響　被旋渦氣流吸引牽制折返[Agnes Affected by Another Storm, Drawn and Constrained by Vortex Airflow to Turn Back]. Kung Sheung Daily News (in Chinese). 1978-07-30. p. 1.
  7. 1 2 罗树森 (1982). "7807号台风的初步分析" 7807号台风的初步分析[Preliminary Analysis of Typhoon No. 7807]. Guangxi Meteorology (in Chinese) (3): 7–8.
  8. ↑ "八號風球高懸 愛娜斯今晚港南掠過" 八號風球高懸　愛娜斯今晚港南掠過[Signal No. 8 Hoisted, Agnes to Pass South of Hong Kong Tonight]. Kung Sheung Evening News (in Chinese). 1978-07-26. p. 1.
  9. ↑ "愛娜斯蓮步姍姍 潑辣狂風傷百人" 愛娜斯蓮步姍姍　潑辣狂風傷百人[Agnes Moves Slowly, Fierce Winds Injure Hundreds]. Kung Sheung Evening News (in Chinese). 1978-07-27. p. 1.
  10. 1 2 "Rèdài qìxuán jǐnggào xìnhào" 熱帶氣旋警告信號 [Tropical Cyclone Warning Signals]. Warning and Signals Database (in Chinese). Hong Kong Observatory. Archived from the original on 2019-12-16. Retrieved 2025-09-03.
  11. ↑ "Gǎng rén suī huà bàibài ài nà sī wú yuàn zǒu" 港人雖話拜拜　愛娜斯唔願走[Hong Kong Says Goodbye, but Agnes Refuses to Leave]. Kung Sheung Evening News (in Chinese). 1978-07-28. p. 1.
  12. ↑ "Háoyǔ chéng zāi hóng dēng liàng qǐ ài nà sī diàotóu pò fǎn gǎng" 豪雨成災紅燈亮起　愛娜斯掉頭迫返港[Heavy Rain Causes Disaster, Agnes Turns Back Toward Hong Kong]. Kung Sheung Evening News (in Chinese). 1978-07-29. p. 1.
  13. ↑ "Fēng jiě huítóu xiào yǒu yùzhào shàng shìjì rén jīngyàn zhī tán" 風姐回頭笑有預兆　上世紀人經驗之談[Storm's Return Foretold, Wisdom from Past Generations]. Wah Kiu Yat Po (in Chinese). 1978-07-30. p. 5.
  14. ↑ "Ài nà sī huítóu xiào wǔyè lüèguò gǎngnán" 愛娜斯回頭笑　午夜掠過港南[Agnes Turns Back, Passes South of Hong Kong at Midnight]. Wah Kiu Yat Po (in Chinese). 1978-07-30. p. 5.
  15. ↑ "Ài nà sī chuàng liǎng xiàng jìlù liǎng dù guà bā hào fēng qiú dé shuǐ yú bǎi yì jiālún" 愛娜斯創兩項紀錄　兩度掛八號風球　得水逾百億加侖[Agnes Sets Two Records: Signal No. 8 Hoisted Twice, Over 10 Billion Gallons of Water]. Kung Sheung Daily News (in Chinese). 1978-07-31. p. 1.
  16. ↑ "Shuǐshàng jiāotōng duànjué" 水上交通斷絕[Maritime Transport Halted]. Kung Sheung Evening News (in Chinese). 1978-07-26. p. 1.
  17. ↑ "Bā hào fēng qiú zuórì xiàwǔ xiè xià hǎilù kōng jiāotōng huīfù" 八號風球昨日下午卸下　海陸空交通恢復[Signal No. 8 Lowered Yesterday Afternoon, Sea, Land, and Air Transport Resumed]. Ta Kung Pao (in Chinese). 1978-07-27. p. 4.
  18. ↑ "Ài nà sī qù ér fù fǎn bā hào fēng qiú zàidù xuánguà" 愛娜斯去而復返　八號風球再度懸掛[Agnes Returns, Signal No. 8 Hoisted Again]. Ta Kung Pao (in Chinese). 1978-07-30. p. 4.
  19. ↑ "Section 4: Tropical Cyclone Statistics". Èr líng yījiǔ nián rèdài qìxuán [二〇一九年熱帶氣旋]二〇一九年熱帶氣旋 [Tropical Cyclones in 2019](PDF) (Report) (in Chinese). Hong Kong Observatory. 2020. Archived (PDF) from the original on 2020-09-06. Retrieved 2025-09-03.
  20. ↑ "Shòu táifēng liǎng dù chuī xí xīnjiè cài huǐ yú shī" 受颱風兩度吹襲　新界菜毀魚失[New Territories Crops and Fish Devastated by Typhoon's Double Strike]. Ta Kung Pao (in Chinese). 1978-08-01. p. 4.
  21. ↑ "Wǔ rì fēngyǔ nóng yú sǔnshī dà wǔbǎi mǔ nóngtián yānmò guǒshū yuē jiǎnchǎn yībàn" 五日風雨農漁損失大　五百畝農田淹沒　果蔬約減產一半[Five Days of Storms Cause Heavy Agricultural Losses, 500 Acres Flooded, Fruit and Vegetable Production Halved]. Kung Sheung Evening News (in Chinese). 1978-07-31. p. 2.
  22. ↑ "Lián chǎng fēngyǔ qīnxí yǔn pòjiù lóu zāoyāng" 連場風雨侵襲　殞破舊樓遭殃[Relentless Storms Damage Old Buildings]. Kung Sheung Daily News (in Chinese). 1978-08-01. p. 8.
  23. ↑ "Chái wān jiǎo cūn yǐn shuǐdào bēngtā shānhóng huǐ wū sìshí" 柴灣角村引水道崩塌　山洪毀屋四十[Chai Wan Kok Drainage Channel Collapses, Flood Destroys 40 Houses]. Ta Kung Pao (in Chinese). 1978-07-31. p. 4.
  24. ↑ "Dí shì duò shuǐ dàng liǎng sǐzhě yǐ chá míng wèi shātián cài fàn" 的士墮水氹兩死者　已查明為沙田菜販[Two Taxi Passengers Confirmed as Sha Tin Vegetable Vendors]. Ta Kung Pao (in Chinese). 1978-07-31. p. 4.
  25. ↑ "Mǎ zǐ kēng tā ní yā huǐ mùwū mǔ huómái zǐ fùshāng" 馬仔坑塌泥壓毀木屋　母活埋子負傷[Ma Chai Hang Mudslide Destroys Wooden House, Mother Buried, Son Injured]. Ta Kung Pao (in Chinese). 1978-07-30. p. 4.
  26. ↑ "Yì yuán sài gǒu qǔxiāo" 逸園賽狗取消[Canidrome Greyhound Racing Canceled]. Kung Sheung Daily News (in Chinese). 1978-07-26. p. 1.
  27. ↑ "Fēngbào xià de àomén xìng wú shāngwáng shìjiàn" 風暴下的澳門幸無傷亡事件[No Casualties Reported in Macau During Storm]. Kung Sheung Daily News (in Chinese). 1978-07-27. p. 1.
  28. ↑ "Ài nà sī lüè guòhòu àomén sǔnshī qīngwéi" 愛娜斯掠過後　澳門損失輕微[Minor Damage in Macau After Agnes Passes]. Ta Kung Pao (in Chinese). 1978-07-27. p. 4.
  29. ↑ "Àomén yǐngxiǎng bù dà jǐn yī mù lóu dǎotā" 澳門影響不大　僅一木樓倒塌[Macau Largely Unaffected, Only One Wooden Building Collapses]. Kung Sheung Daily News (in Chinese). 1978-07-30. p. 7.
  30. ↑ "Àomén fēng qiú qīngchén chú xià" 澳門風球清晨除下[Macau Storm Signal Lowered in Early Morning]. Wah Kiu Yat Po (in Chinese). 1978-07-31. p. 6.
  31. ↑ "Ài nà sī pín gǎi fēngxiàng bù lái yòu lái bā hào fēng qiú zhī xià xiānggǎng dà luàn" 愛娜斯頻改風向不來又來　八號風球之下香港大亂[Agnes Frequently Changes Direction, Hong Kong in Chaos Under Signal No. 8]. Ta Kung Pao (in Chinese). 1978-07-27. p. 4.
  32. ↑ "Ài nà sī zhí qū huánán" 愛娜斯直趨華南[Agnes Heads Directly for Southern China]. Ta Kung Pao (in Chinese). 1978-07-30. p. 4.
  33. ↑ 江彥文 (2006). Zhōngguó qìxiàng zāihài dàdiǎn. Guǎngdōng juǎn中國氣象災害大典．廣東卷[Encyclopedia of Meteorological Disasters in China: Guangdong Volume] (in Simplified Chinese). Beijing, China: Meteorological Press. ISBN   750294155X.
  34. ↑ "Shù shí niánlái zuì yánzhòng lièrì kùrè yàzhōu qū shù bǎi rén sàngshēng dàlù shí shěng nóngtián jūn liè" 數十年來最嚴重烈日酷熱　亞洲區數百人喪生大陸十省農田龜裂[Decades' Worst Heatwave, Hundreds Dead in Asia, Farmland Cracked in Ten Chinese Provinces]. Kung Sheung Evening News (in Chinese). 1978-07-29. p. 8.
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Severe Tropical Storm Agnes
Agnes 1978.png
Agnes on July 26, as it first approached Hong Kong