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202004W (SINLAKU 森拉克) - Profile 檔案

(First draft issued on August 8, 2020)
(初稿於 2020 年 8 月 8 日發出)

Brief profile of SINLAKU | 森拉克小檔案:

JTWC number 聯合颱風警報中心 (JTWC) 號碼 04W
International number 國際編號 2003
Period of existence 生存時期 (JTWC) 2020/07/31 08 HKT - 2020/08/03 08 HKT
Lifetime 壽命 (JTWC) 3.00 days 日
Maximum 1-minute wind (JTWC) JTWC 一分鐘平均最高中心風速

35 knots 節 (Tropical Storm 熱帶風暴)

Minimum pressure (JTWC) JTWC 最低氣壓 993 hPa 百帕
Highest TC signal by HKO
香港天文台發出最高熱帶氣旋警告信號
3 (Strong Wind Signal 強風信號)
Closest point of approach by HKO
香港天文台所示之最接近距離
SSW 520 km (real-time warning 實時報告)
Time of closest approach by HKO
香港天文台所示之最接近時間
2020/07/31 21 HKT (real-time warning 實時報告)
Lowest pressure recorded at HKO
香港天文台錄得的最低氣壓
TBA 稍後公佈

TC signals in Hong Kong* 香港曾經生效的熱帶氣旋警告*:

Signal
信號
Date and time
日期和時間
Distance from HK
與香港的距離
Predicted movement
預測移動趨勢
Max. 10-min winds
中心最高十分鐘平均風速
2020/07/31 (FRI) 20:40 HKT** SSW 520 km WNW at 18 km/h 45 km/h (25 knots, TD)
2020/08/01 (SAT) 21:10 HKT WSW 760 km WNW at 20 km/h 55 km/h (30 knots, TD)
2020/08/01 (SAT) 23:15 HKT WSW 770 km WNW at 18 km/h 55 km/h (30 knots, TD)

*Based on the information from real-time tropical cyclone warning bulletins.
*根據實時熱帶氣旋警報資料。

**The #3 Strong Wind Signal was issued to replace the Strong Monsoon Signal.
**強烈季候風信號被此三號強風信號取代。

Percentile Ranks 百分等級:

TBA 稍後公佈

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

TC tracks from HKO 天文台的熱帶氣旋路徑圖:

TBA 稍後公佈

Past HKWW Bulletins 本站發佈

Please click here for bulletins on this tropical cyclone. 請按這裡

Storm Development Overview 風暴發展概覽

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)

SINLAKU was the first sign of tropical cyclone activity in the northwest Pacific Ocean after the long period of subtropical ridge dominance in the area in most of July. As the ridge left the area, a broad area of low pressure appeared near the Philippines. Numerical model forecasts expected the system to enter the South China Sea and develop gradually.

On July 30, the low pressure area coded 91W entered central South China Sea and moved west-northwest along the periphery of the ridge. Being a monsoon depression, 91W's circulations were rather loose but the system covered a large area of the Sea. Its centre began to improve on July 31; the JMA issued a gale warning on the system at 8 am, while the NMC recognized the system as a tropical depression at 2 pm that day. The JTWC issued a tropical cyclone formation alert that night.

The HKO upgraded 91W into a tropical depression as well. The system maintained its movement towards the west-northwest on August 1 and crossed southern Hainan that morning. The JTWC recognized it as a tropical storm and issued the first warning bulletin in the afternoon, while the JMA upgraded it into tropical storm SINLAKU.

SINLAKU crossed the Gulf of Tonkin during the night of August 1 and morning of August 2. It made landfall in northern Vietnam in the early afternoon, and gradually weakened into an area of low pressure later that night.

經過 7 月大部分時間副熱帶高壓脊佔據西北太平洋,森拉克為此後首次有熱帶氣旋於該區形成。隨著副高移離,一個廣闊低壓區於菲律賓一帶出現。數值模式預報大多預料該系統將進入南海,並逐漸發展。

該低壓 (91W) 於 7 月 30 日進入南海中部,並沿副高周邊向西北偏西移動。由於 91W 是一個季風低壓,其對流較為鬆散,並覆蓋南海較大範圍。它的中心附近於 31 日有所改善,日本氣象廳於上午 8 時對其發出烈風警告,而中國中央氣象台於下午 2 時將其定為熱帶低氣壓。聯合颱風警報中心於當晚發出熱帶氣旋形成警報。

香港天文台亦將 91W 升格為熱帶低氣壓。該系統於 8 月 1 日繼續向西北偏西移動,於早上橫過海南南部。聯合颱風警報中心將其定為熱帶風暴,並於下午發出首次發佈,而日本氣象廳則將其升格為熱帶風暴森拉克。

森拉克於 1 日晚間及 2 日早上橫過北部灣,下午登陸越南北部,並於晚間逐漸減弱為低壓區。

Weather in Hong Kong During Approach 風暴影響時香港天氣狀況

Link to relevant HKO weather report bulletins: 31/71/8
香港天文台相關天氣報告連結31/71/8

After a record-breaking period of very hot weather in July, the weather turned unstable on July 31. Being a monsoon depression, SINLAKU's strong winds in its periphery started to affect Hong Kong that morning. Offshore and elevated locations such as Cheung Chau, Waglan Island and Tate's Cairn were among the first to feel the force. The HKO issued the Strong Monsoon Signal at 7:05 am and mentioned later in the morning that the signal would be replaced by a tropical cyclone signal if the monsoon depression developed into a tropical cyclone. Over the rest of the day, SINLAKU's outer rainbands produced squally showers in the territory, and strong force easterly winds continued to affect Hong Kong.

As SINLAKU was upgraded into a tropical depression at 8:40 pm, the HKO cancelled the Strong Monsoon Signal and replaced it with the #3 Strong Wind Signal. This marked the first time a #3 Signal was used to replace the Strong Monsoon Signal since Typhoon DOT in September 1993, and the first time the #1 Signal was skipped since the unnamed tropical depression in June 2000. At about 520 km south-southwest of the territory, SINLAKU had already travelled past its closest point of approach to Hong Kong, and was expected to recede gradually. As a result, the HKO mentioned that higher signals were unlikely.

Winds remained strong on August 1; Gales were briefly recorded at Cheung Chau shortly before 8 am (and a few times later in the day). There was a general decrease in wind speed in the late afternoon; the #3 Signal was replaced by the #1 Standby Signal at 9:10 pm, when SINLAKU was at about 760 km west-southwest of Hong Kong. Soon after, the #1 Signal was cancelled at 11:15 pm as SINLAKU was about to be beyond 800 km from the territory.

Nevertheless, SINLAKU's rainbands were still affecting Hong Kong, and strong force winds were still being recorded occasionally soon after the cancellation of tropical cyclone signals. Local weather did not improve significantly after SINLAKU's departure, as Hong Kong was under the influence of an active southerly airstream.

香港 7 月經歷破紀錄的連續酷熱天氣,至 31 日天氣轉為不穩定。由於森拉克是季風低壓,其周邊的強風於當天早上開始影響香港。離岸及高地如長洲、橫欄島及大老山等率先感受到;天文台於上午 7 時 05 分發出強烈季候風信號,並於上午稍後表示如該季風低壓發展為熱帶氣旋,天文台將改發熱帶氣旋警告信號。森拉克的外圍雨帶於 31 日餘下時間繼續影響本港,有狂風驟雨及吹強風程度東風。

隨著森拉克於下午 8 時 40 分被升格為熱帶低氣壓,天文台取消強烈季候風信號並改發三號強風信號。這是自 1993 年 9 月颱風黛蒂以來首次以三號強風信號替代強烈季候風信號,亦是自 2000 年 6 月無名熱帶低氣壓以來首次跳過一號戒備信號而直接發出三號強風信號。改發信號之時,森拉克於香港西南偏南約 520 公里處,風暴已過最接近香港的地方。由於預計風暴會逐漸遠離香港,天文台表示改發更高信號機會不大。

本港風勢於 8 月 1 日仍然偏強,長洲於上午 8 時前短暫錄得烈風,而當天稍後亦數次有烈風記錄。下午後段本港整體風勢減弱,天文台於下午 9 時 10 分改發一號戒備信號,當時森拉克位於香港西南偏西約 760 公里。不久後,隨著森拉克靠近本港 800 公里範圍邊緣,一號信號亦於下午 11 時 15 分取消。

雖然信號已經取消,但森拉克的雨帶仍然影響本港,初期部分地區仍間中吹強風。森拉克移離後,香港轉受一股偏南氣流的影響,天氣並沒有明顯改善。

Image Gallery 圖片庫

Figure 1 - Steering flow chart at 8 am July 31
圖 1 - 7 月 31 日上午 8 時之駛流場圖

Figure 2 - Satellite image of SINLAKU at its formation
圖 2 - 森拉克初形成時之衛星雲圖

Figure 3 - Wind field analyses at 9:26 pm July 31 (left) and 9:57 am August 1 (right); winds near SINLAKU's centre had strengthened in these 12 hours.
圖 3 - 7 月 31 日下午 9 時 26 分 (左) 及 8 月 1 日上午 9 時 57 分 (右) 之風場掃描圖,可見森拉克近中心風力於 12 小時間有所增強

Figure 4 - Local wind distribution map at 7:50 am August 1
圖 4 - 8 月 1 日上午 7 時 50 分之本港風勢分布圖

Figure 5 - Radar image at 9 am August 1
圖 5 - 8 月 1 日上午 9 時之雷達圖

Figure 6 - Wind speed time series at Chek Lap Kok, Cheung Chau, Sai Kung and Kowloon Star Ferry Pier (top to bottom) on August 1
圖 6 - 赤鱲角、長洲、西貢及九龍天星碼頭 (上至下) 於 8 月 1 日之風速時間序列圖

Figure 7 - Satellite image of SINLAKU moving across the Gulf of Tonkin
圖 7 - 森拉克橫過北部灣時之衛星雲圖

Figure 8 - JMA's forecast track at 2 pm August 1; note the large estimated coverage of 30-kt wind area
圖 8 - 8 月 1 日下午 2 時日本氣象廳之預測圖,留意估計 30 節風速區覆蓋範圍甚廣

Figure 9 - Forecast tracks from various official agencies at 2 pm August 1
圖 9 - 8 月 1 日下午 2 時各官方氣象台之預測路徑

Figure 10 - Daily rainfall map for July 31 (left) and August 1 (right)
圖 10 - 7 月 31 日 (左) 及 8 月 1 日 (右) 之總雨量圖

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

Station
風速站
Max. 10-min avg. wind speed
最高十分鐘平均風速
Beaufort classification
蒲福氏風級分類
Chek Lap Kok 赤鱲角 57 km/h STRONG 強風
Cheung Chau 長洲 77 km/h GALE 烈風
Kai Tak 啟德 45 km/h STRONG 強風
Lau Fau Shan 流浮山 36 km/h* Fresh 清勁
Sai Kung 西貢 51 km/h STRONG 強風
Sha Tin 沙田 24 km/h Moderate 和緩
Ta Kwu Ling 打鼓嶺 28 km/h Moderate 和緩
Tsing Yi (SHL) 青衣蜆殼油庫 33 km/h Fresh 清勁

*A sustained wind speed of 42 km/h (strong force) was recorded at Lau Fau Shan near 3 pm July 31, before the issuance of the #3 Signal.
*三號信號發出前,流浮山曾於 7 月 31 日下午約 3 時錄得持續風速每小時 42 公里,達強風程度。

Number of stations recording at least STRONG force (force 6 - 7) winds: 4
Number of stations recording at least GALE force (force 8 - 9) winds: 1
Number of stations recording at least STORM force (force 10 - 11) winds: 0
Number of stations recording HURRICANE force (force 12) winds: 0

錄得 強風 (6 - 7 級) 或更高風速的站數: 4
錄得 烈風 (8 - 9 級) 或更高風速的站數: 1
錄得 暴風 (10 - 11 級) 或更高風速的站數: 0
錄得 颶風 (12 級) 風速的站數: 0

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

YYMMDDZZ Lat Long Wind
20073112 178N1129E 030
20073118 178N1117E 030
20080100 180N1110E 030
20080106 182N1098E 035
20080112 186N1080E 035
20080118 191N1072E 035
20080200 194N1064E 035
20080206 195N1056E 035
20080212 197N1049E 030

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 (英文)

TBA 稍後公佈

Table 3: Rainfall (in millimetres) contributed by SINLAKU 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 (英文) (方括號內之數據由不完整之每小時資料擷取)

TBA 稍後公佈

Last Accessed 最近訪問日期: Mon Sep 28 2020 18:52:08 HKT
Last Modified 最近修訂日期: Fri Aug 21 2020

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