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TC Watch / 熱帶氣旋 > Selected TC Review / 重要熱帶氣旋回顧 > 201510W (LINFA 蓮花) [Refresh 更新]

201510W (LINFA 蓮花) - Profile 檔案

(First draft issued on July 20, 2015; final version issued on July 27, 2015)
(初稿於 2015 年 7 月 20 日發出，最後版本於 2015 年 7 月 27 日上載)

Brief profile of LINFA 蓮花小檔案:

TC signals for Hong Kong & Track 香港曾經生效的熱帶氣旋警告和路徑圖:

Table 表:

Signal 信號	Date and time 日期和時間	Distance from HK 與香港的距離	Predicted movement 預測移動方向和速度	Max. 10-min winds 中心最高十分鐘平均風速
	2015/07/08 (WED) 07:40 HKT	ESE 490 km	N slowly → W	105 km/h (55 knots, STS)
	2015/07/09 (THU) 08:40 HKT	E 270 km	W at 16 km/h	130 km/h (70 knots, CAT. 1 / T)
	2015/07/09 (THU) 16:40 HKT	NE 110 km	W at 22 km/h	105 km/h (55 knots, STS)
	2015/07/09 (THU) 22:10 HKT	NNW 60 km	W/WSW at 22 km/h	65 km/h (35 knots, TS)
	2015/07/10 (FRI) 05:50 HKT	W 180 km	WSW at 22 km/h	40 km/h (20 knots, LPA)

Figure 圖:

Percentile Ranks 百分等級:

IR imagery animation 紅外線雲圖動畫:

TC track from HKWW 本站的熱帶氣旋路徑圖:

TC track from HKO 天文台的熱帶氣旋路徑圖:

Past HKWW Bulletins on LINFA 本站有關蓮花的發佈

Please click here for bulletins on LINFA. 請按這裡。

Storm Formation and Development 氣旋形成和發展

Unless otherwise stated, all times below are in Hong Kong Standard Time (UTC+8)
除非特別註明，下文時間均為香港標準時間 (協調世界時加 8 小時)

LINFA formed as tropical depression 10W in the morning of July 2. This came at an active period in the northwestern Pacific, following the formation of 09W (CHAN-HOM) two days ago and was followed by 11W (NANGKA) a day later. At the time of its formation, 10W was generally expected to track WNW along the southwestern periphery of the subtropical ridge towards northeastern Luzon. The storm was expected to move slowly as it was far away from the ridge and steering was rather weak. Numerical models predicted that the ridge would then retreat, allowing 10W to turn north as it neared Luzon. Thereafter, models showed great discrepancies in their predictions due to the possible interaction with CHAN-HOM, which would then be heading towards the Ryukyu Islands and close enough to interfere with 10W's track.

During the day of July 2, 10W gradually picked up convections but the moderate vertical wind shear in the region caused most of them to be displaced to the west. Nevertheless, it intensified into a tropical storm that night as the JMA assigned it the name LINFA. After an initial motion towards the NW, LINFA turned equatorward on July 3. Although still showing some effect of the shear, LINFA had become a compact spinning system and appeared to be developing a central dense overcast. The JMA upgraded LINFA into a severe tropical storm at 2 pm. The storm turned WNW later that day and accelerated on July 4. It made landfall at Luzon later that night, but various agencies disagreed on the timing. Fixes from the HKO, JMA and PAGASA of the Philippines showed that LINFA made landfall before or near 2 am July 5, but the CMA and JTWC put the storm's centre at a more northerly location and thus their 2 am fixes were still at some distance from shore.

As is frequently seen in other storms, LINFA sped past Luzon in a equatorward motion during the daytime of July 5. Initially almost all agencies predicted that LINFA would turn north as it crossed Luzon in response to the weakening of the subtropical ridge. However, such quick motion meant that LINFA was in the South China Sea by the end of July 5, forcing all agencies to adjust their forecast tracks westward. Together with numerical models' inability to predict accurately the atmospheric configuration as LINFA moved north and neared Taiwan, it meant that LINFA's future development remained highly variable. The HKO was the first agency to make a significant change to LINFA's forecast track; instead of skirting Taiwan's eastern shore, HKO's revised forecast on July 5 depicted an initial turn to the N/NNE, followed by an abrupt deflection to the west into the Taiwan Strait and then an anticlockwise turn to northern South China Sea, degenerating at a distance of around 200 km from Hong Kong. This was probably a response to ECMWF's change in forecast philosophy which depicted a similar scenario. For the majority of other forecast centres, however, LINFA's speed was kept low near the end of the forecast period, making it linger around coastal Taiwan by the end of their 5-day forecasts.

蓮花於 7 月 2 日開始發展，聯合颱風警報中心將其升格為熱帶低氣壓 10W。當時西北太平洋熱帶氣旋活動漸趨活躍，兩天前 09W (燦鴻) 剛形成，而翌日 11W (浪卡) 亦發展起來。10W 形成之時，一般預計它將沿副熱帶高壓脊西南部向西北偏西移動，大致趨向呂宋東北部。由於 10W 距離副高較遠，該處流場較弱，所以預測速度並不高。數值模式預計副高將東退，令 10W 於靠近呂宋時北轉。其後各模式對 10W 的路徑出現較大分歧，這是由於預料屆時燦鴻將靠近琉球群島，兩者的距離縮小令藤原效應出現的機會增加。

10W 於 2 日日間對流漸長，但由於該區垂直風切變不低，對流大多被切離至風暴西面。雖然如此，10W 於當晚增強為熱帶風暴，日本氣象廳將其命名為蓮花。蓮花初時向西北移動，但於 3 日開始以偏西方向前進。當天風暴仍受風切影響，但蓮花已發展為一緊密旋轉的系統，並似乎正在發展出一中心密集雲區。日本氣象廳於下午 2 時將蓮花升格為強烈熱帶風暴。蓮花於當天較後時間開始向西北偏西移動，並於 4 日加速。它於 4 日晚登陸呂宋，但各機構對其登陸時間有不同說法。香港天文台、日本氣象廳及菲律賓大氣地球物理和天文服務管理局的定位顯示風暴於 5 日上午 2 時左右或之前登陸，但中國中央氣象台及聯合颱風警報中心對其定位較北，因此它們於 2 時的定位顯示風暴與岸邊仍有一段距離。

與以往很多登陸呂宋的風暴一樣，蓮花於 5 日早上快速向西移動並橫過呂宋。各氣象台初時預計蓮花將因副高減弱而於橫過呂宋時轉北，但蓮花於 5 日晚間已經進入南海，氣象台不得不把預測路徑西調。由於數值模式未能準確預測蓮花北移並靠近台灣時的大氣配置，蓮花未來的發展因而出現極大變數。香港天文台是首間大幅調整蓮花預測路徑的機構，它們於 5 日把路徑由原先的掠過台灣東岸改為先向北或東北偏北移動，其後突轉西移進入台灣海峽，繼而以逆時針方向於南海北部前進，並於香港約 200 公里外消散。天文台的改動有可能是因為歐洲中期天氣預報中心的預測出現這一轉變而觸發。至於其他氣象台則預計蓮花於預測後期速度較慢，5 天後仍於台灣沿岸徘徊。

Figure 1 - Satellite image of LINFA at formation
圖 1 - 蓮花形成時的衛星雲圖

Figure 2 - ECMWF's ensemble forecast tracks for LINFA (left), CHAN-HOM (centre) and NANGKA (right). LINFA's potential tracks were rather spread out.
圖 2 - 歐洲中期預報中心對於蓮花 (左)、燦鴻 (中) 及浪卡 (右) 的集成預測路徑圖，可見蓮花的預報出現頗大分歧

Figure 3 - Forecast tracks from different official agencies on July 5
圖 3 - 7 月 5 日各官方氣象台之預測路徑圖

Crossing South China Sea and Westward Turn 橫過南海及西轉

After entering the South China Sea, LINFA decelerated and turned north on July 6. It was downgraded into a tropical storm by all agencies that use 10-minute average wind speeds as the effect of crossing Luzon became apparent: deep-layered convections retreated to the storm's western periphery, exposing its low-level circulation centre. At this point, LINFA was still expected to move NNE towards southern Taiwan, but model guidance had started to converge at the solution of a westerly deflection towards Fujian. This modification was the result of a change in the predicted strength of the subtropical ridge. The ridge was expected to strengthen again, pushing LINFA westward and reducing the degree of interaction between LINFA and CHAN-HOM.

As LINFA moved north, it steered away from the Luzon coast and intensify. It reached severe tropical storm strength again on July 7 and was losing longitude at times. The predicted track towards the NNE never materialized; forecast tracks were shifted westward again and a landfall in eastern Guangdong seemed likely. Most predictions then put LINFA on a westerly or even west-southwesterly course, crossing the Pearl River Estuary at reduced strengths. In Taiwan, both the sea and land typhoon warnings were issued; however the land warning remained in force for only 12 hours as the storm did not turn NNE and posed little danger to the Island.

LINFA's convections thinned out during the night of July 7, while its core remained intact. Due to LINFA's potential threat to Hong Kong, the HKO hinted at the possibility of tropical cyclone signals at 5 pm July 7, and later issued the #1 Standby Signal at 7:40 a.m. July 8 when LINFA was at 490 km ESE of the territory. A central dense overcast appeared that morning and a shallow eye appeared on satellite images during the afternoon. Taiwan's radar images also witnessed LINFA's intensification. The CMA upgraded LINFA into a typhoon at 8 pm, while the HKO is holding the cyclone at severe tropical storm strength. LINFA turned WNW during the night of July 8. Its eye became clear in the next couple of hours; the HKO made the upgrade at 6 am July 9. The Weibo channel of Shanwei meterorological unit posted a message at around 4 am that referred to a buoy near LINFA's eyewall which registered a sustained wind speed of 37.6 m/s (135 km/h), justifying LINFA's typhoon intensity.

LINFA was approaching eastern Guangdong steadily that morning; the HKO issued the #3 Strong Wind Signal at 8:40 am. Hardly any station registered strong force winds at that time even though LINFA was only 270 km from Hong Kong; this is typical of cyclones coming in from the east, where N/NW winds were partially shielded. However, the Observatory warned the public about the imminent danger due to LINFA's antipicated close approach. Initially, it mentioned that higher signals may be considered during the afternoon or nighttime of July 9, which was made earlier to the afternoon a few hours later as LINFA accelerated during the day.

進入南海後，蓮花減速並於 6 日轉向北移。橫過呂宋對蓮花的影響開始浮現，它的對流集中於其西部邊緣，令低層環流中心外露，因此各使用十分鐘平均風速標準的氣象台均將其降格為熱帶風暴。這時各機構仍預計蓮花會向東北偏北移動，靠近台灣南部，至於數值預報則開始出現共識，蓮花將西折並趨向福建。這轉變是由於它們上調副高的預測強度，蓮花受重新增強的高壓脊影響而西移，而蓮花與燦鴻間的相互影響亦變得較小。

隨著蓮花北移，它逐漸離開呂宋沿岸，開始重新增強。它於 7 日再次達到強烈熱帶風暴強度，移向間中西偏。先前預計的東北偏北之移向未有兌現，各氣象台再度將預測路徑西調，風暴較大可能會於廣東東部登陸，其後向西甚或西南偏西移動，以較低強度橫過珠江口。台灣當局對蓮花發出海上及陸上颱風警報，但由於蓮花沒有向東北偏北移動，它對台灣的威脅比預期小，陸上警告發出 12 小時後便被解除。

蓮花的對流於 7 日晚間轉薄，但其中心仍然緊密。由於蓮花的預測路徑對香港構成威脅，天文台於 7 日下午 5 時表示將於翌日考慮發出一號戒備信號，而該信號亦如期於 8 日早上 7 時 40 分發出，當時蓮花位於香港東南偏東約 490 公里處。當天早上蓮花成功建立中心密集雲區，下午發展出一較淺風眼，於衛星雲圖上可見，而台灣的雷達圖亦清楚可見蓮花增強。中國中央氣象台於晚上 8 時將蓮花升格為颱風，而天文台則繼續維持強烈熱帶風暴的評級。蓮花於 8 日晚轉向西北偏西移動，其風眼漸轉清晰，天文台於 9 日上午 6 時將風暴升格為颱風。汕尾市氣象局官方微博曾於上午 4 時發文指蓮花眼壁附近的一個浮標站曾錄得每秒 37.6 米 (每小時 135 公里) 的持續風速，足證其達颱風強度。

蓮花於當天早上繼續穩定靠近廣東東部，天文台遂於早上 8 時 40 分改發三號強風信號。雖然當時蓮花距離香港只有 270 公里，但受地形屏蔽影響，幾乎完全沒有氣象站錄得西北至偏北強風，這於從東面靠近的熱帶氣旋中是很常見的。可是，由於預測蓮花會非常接近香港，天文台仍提醒市民蓮花對本港的威脅。初時天文台預料將於 9 日下午至晚間考慮改發更高信號，但由於蓮花於日間加速，天文台數小時後改為於下午考慮。

Figure 4 - Satellite image of LINFA after crossing Luzon
圖 4 - 蓮花橫過呂宋後的衛星雲圖

Figure 5 - Steering flow chart at 8 am July 7
圖 5 - 7 月 7 日早上 8 時之駛流圖

Figure 6 - Forecast tracks from different official agencies on July 8; a close approach to Hong Kong was expected
圖 6 - 7 月 8 日各官方氣象台之預測路徑圖，預期蓮花將非常接近香港

Figures 7a and 7b - Radar (left) and satellite (right) images at around 3 pm July 8
圖 7a 及 7b - 7 月 8 日約下午 3 時之雷達 (左) 及 衛星雲圖 (右)

Landfall and Rapid Weakening 登陸及急速減弱

According to the CMA, LINFA made landfall at Lufeng, Guangdong at around 12:15 pm July 9, packing winds of around 35 m/s (126 km/h). More than 1.6 million people were affected by the impact. LINFA's structure remained intact upon landfall although its eye filled quickly. Locally, handling of cargoes were suspended at 1 pm. Ferry services to outlying islands stopped gradually in the late morning and afternoon. Winds in the territory picked up near noon and early afternoon, blowing in from the northwest. However, most of the stations that registered strong force winds were at offshore locations or on high ground, such as Green Island and Tate's Cairn. As wind speeds continued to rise, the Observatory issued the Pre-No. 8 Special Announcement at 2:40 pm, informing the public that the #8 Signal would be issued by 5 pm the latest. As a result, most employees could leave their workplace earlier than usual, leading to waves of people hurrying to return home.

As LINFA continued to move west, its structure started to degrade especially in its southern semicircle. The HKO downgraded LINFA into a severe tropical storm at 4 pm. Meanwhile, the #8 Northwest Gale or Storm Signal was issued at 4:40 pm. The Observatory indicated that local weather will deteriorate rapidly during the night; also, due to LINFA's small circulation, Hong Kong will only experience gale force winds briefly and the storm would move away the next morning. Local bus services were suspended two hours after the issuance of the #8 Signal.

Paradoxically, winds gradually subsided a few hours into the issuance of the #8 Signal. By 7 pm, only Peng Chau and Chek Lap Kok managed to register strong force winds. Strong winds were essentially non-existent in the territory at around 8 pm. Despite its proximity to the coast, LINFA weakened much faster than expected; its southern rainbands almost dissipated in entirety and so even gusts were weak locally. Post-analysis indicated that this might be the result of dry air intrusion near LINFA's landfall as well as the restriction of moist air from the southwest monsoon due to the presence of the more intense CHAN-HOM near Okinawa. The Observatory downgraded LINFA into a tropical storm at 7 pm and mentioned the possibility of lowering the signal in its bulletin at 8 pm. Although LINFA was still approaching and had started losing latitude, it was quite clear by then that its threat to Hong Kong was limited.

At a distance of around 50 km from the Observatory, LINFA was closest to Hong Kong near 9 pm and it later crossed the Pearl River Estuary. The #3 Strong Wind Signal was issued at 10:10 pm. Winds turned west while the strength was probably similar to a normal day, if not weaker. It was downgraded into a tropical depression at 11 pm. At Macau, the highest signal issued was the #3 Strong Wind Signal; winds were equally light over there.

Soon after the signal change, local wind direction backed to the southeast. Several stations saw a surge in wind speed; for example, Ngong Ping registered strong force winds at around 12:30 am July 10, the first such occurrence during LINFA's passage. A rainband associated with LINFA's outer circulation swept across Hong Kong between 4 am and 6 am, leading to generally stronger winds over the territories; strong force winds were observed at Cheung Chau, Green Island, Ngong Ping, Tai Mei Tuk, Tate's Cairn and Waglan Island, with winds at some stations reaching gale force at times.

As LINFA moved further away, the Observatory cancelled the #3 Strong Wind Signal at 5:50 am July 10. The storm was also downgraded into an area of low pressure. The weather improved during the day with sunny periods, and winds gradually turned light following the passage of LINFA's final rainband.

LINFA's approach resulted in relatively little damage in the territory. The government received 2 cases of fallen trees while there were no reports of floods. Soon after the cancellation of the #8 Signal, the Observatory issued a statement about its decision to issue the #8 Signal. It was revealed that an aircraft was despatched in the morning of July 9 to undertake meterological observations near LINFA's centre, and confirmed that LINFA was indeed packing winds of hurricane force and possessed a gale radius of around 100 km. The #8 Signal was issued for the sake of public safety. However, LINFA weakened quicker than expected and gale force winds just missed the territory.

根據中國氣象台資料，蓮花於 9 日下午約 12 時 15 分登陸廣東陸豐，登陸時風速達每秒 35 米 (每小時 126 公里)，受災人數達 160 萬。雖然蓮花的風眼很快便被填塞，但其結構於登陸後仍然維持完整。本地方面，貨櫃交收於下午 1 時停止，而來往離島的渡輪服務則於早上後段及下午陸續暫停。本地風勢於正午及下午初段增強，風向為西北，但大多錄得強風的氣象站均位處高地或離岸地區，如青洲及大老山。隨著風力漸增，天文台於下午 2 時 40 分發出預警，表示將最遲於下午 5 時改發八號信號；這令多數僱員提早下班，各處出現趕著回家的人潮。

蓮花登陸後繼續西移，風暴尤其是南半圓開始崩潰。天文台於下午 4 時將蓮花降格為強烈熱帶風暴，並於下午 4 時 40 分發出八號西北烈風或暴風信號。同時，天文台表示香港天氣將於晚間急速轉壞，且由於蓮花環流細小，香港受烈風影響的時間將較短，風暴會於翌日早上移離。本地巴士服務於八號信號發出兩小時後陸續暫停。

令人意想不到的是八號信號發出後本港風勢不升反跌。至下午 7 時，只有坪洲及赤鱲角錄得強風；而到下午 8 時，本港更幾乎沒有地方吹強風。雖然蓮花一直距離岸邊不遠，但其減弱速度比預期快得多。由於其南面雨帶已差不多完全消散，陣風風力亦弱。事後分析顯示這可能是由於蓮花登陸前後受乾空氣入侵，而且由於燦鴻當時已達沖繩島，它阻礙了西南季候風水氣的輸送。天文台於下午 7 時將蓮花降格為熱帶風暴，並於下午 8 時開始提及將信號下調的可能性。蓮花繼續靠近香港並開始南移，但明顯地它對香港的影響將十分有限。

蓮花於晚上 9 時最為接近香港，於天文台以北 50 公里外掠過，其後橫過珠江口。天文台於晚上 10 時 10 分改發三號強風信號。風向轉為偏西，風力則與正常日子相若。一小時後，天文台進一步將蓮花降格為熱帶低氣壓。澳門方面，當地最高熱帶氣旋警告信號為三號風球，風勢同樣不大。

改發三號信號後不久，本港風向開始轉為東南，部分地區風勢轉強，如昂坪於 10 日凌晨 12 時 30 分首次吹強風。蓮花的一條外圍雨帶於上午 4 至 6 時橫過本港，令本地風勢普遍增強。長洲、青洲、昂坪、大美督、大老山及橫瀾島吹強風，部分地區更間中吹烈風。

隨著蓮花移離，天文台於 10 日上午 5 時 50 分取消三號信號，並將蓮花降格為低壓區。當天香港天氣逐漸好轉，部分時間有陽光，風勢亦隨著蓮花最後一道雨帶通過後而轉弱。

蓮花來襲對香港構成的損害相對輕微。政府共接獲兩宗塌樹報告，但並未接獲水浸報告。八號信號取消後不久，天文台發出新聞稿，解釋其發出八號信號的因由。政府曾於 9 日早上派飛機前往蓮花中心附近讀取氣象數據，證實當時近中心確吹颶風，而其烈風圈達 100 公里。天文台基於市民安全考慮而發出八號信號，但由於蓮花減弱速度較預期快，其烈風圈收細而令本港與烈風擦身而過。

Figures 8a and 8b - Radar (left) and satellite (right) images of LINFA just before its landfall
圖 8a 及 8b - 蓮花即將登陸前之雷達 (左) 及 衛星雲圖 (右)

Figures 9a and 9b - Wind field analysis on July 8 (left) and 9 (right). Winds in Hong Kong coastal waters were weak at LINFA's approach.
圖 9a 及 9b - 7 月 8 (左) 及 9 日 (右) 之風場分析，可見蓮花靠近時香港鄰近海域的風勢較弱

Figure 10 - Estimated wind field at 8 pm July 9
圖 10 - 7 月 9 日下午 8 時之估算風場圖

Figure 11 - Satellite image of LINFA at closest approach to Hong Kong
圖 11 - 蓮花最接近香港時之衛星雲圖

Figures 12a to 12f - Local wind disitribution maps at 4-hour intervals from noon July 9 to 8 am the next day
圖 12a 至 12f - 7 月 9 日正午至翌日上午 8 時每四小時的本港風勢分布圖

Figures 13a to 13f - Radar images at 4-hour intervals from noon July 9 to 8 am the next day
圖 13a 至 13f - 7 月 9 日正午至翌日上午 8 時每四小時的雷達圖

Figures 14a to 14d - Wind speed time series at Chek Lap Kok, Kai Tak, Lau Fau Shan and Waglan Island during LINFA's approach
圖 14a 至 14d - 赤鱲角、啟德、流浮山及橫瀾島於蓮花襲港時的風速時間序列圖

Figure 15 - Sea level pressure time series at the Hong Kong Observatory
圖 15 - 香港天文台的海平面氣壓時間序列圖

Winds Recorded at Reference Stations 參考站所錄得的風速

*Recorded after the cancellation of the #3 Strong Wind Signal. 於三號強風信號解除後錄得。

Charts and Figures 各項數據

Table 1: Track data from HKWW:
表一 : 香港天氣觀測站之路徑資料

Table 2: Maximum gust and hourly average wind speed recorded in Hong Kong from HKO:
表二 : 香港天文台公佈的各站最高每小時平均風力和陣風數據

Table 3: Rainfall (in millimetres) contributed by LINFA from HKO (figures in brackets are based on incomplete hourly data):
表三 : 香港天文台公佈的各站雨量資料 (方括號內之數據由不完整之每小時資料擷取)

Last Accessed 最近訪問日期: Sat Mar 22 2025 15:10:39 HKT
Last Modified 最近修訂日期: Mon Jul 24 2023