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201722W - Profile 檔案

(First draft issued on October 7, 2017; final version issued on January 16, 2018)
(初稿於 2017 年 10 月 7 日發出,最後版本於 2018 年 1 月 16 日上載)

Brief profile of 22W | 22W 小檔案:

JTWC number 聯合颱風警報中心 (JTWC) 號碼 22W
International number 國際編號 ----
Period of existence 生存時期 (JTWC) 2017/09/24 02 HKT - 2017/09/25 14 HKT
Lifetime 壽命 (JTWC) 1.50 days 日
Maximum 1-minute wind (JTWC) JTWC 一分鐘平均最高中心風速 30 knots 節 (Tropical Depression 熱帶低氣壓)
Minimum pressure (JTWC) JTWC 最低氣壓 1000 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
1 (Standby Signal 戒備信號)
Closest point of approach by HKO
香港天文台所示之最接近距離
SSW 430 km (real-time warning 實時報告) / SSW 470 km (TC report 熱帶氣旋報告)
Time of closest approach by HKO
香港天文台所示之最接近時間
2017/09/24 09 HKT (real-time warning 實時報告) / 08 HKT (TC report 熱帶氣旋報告)
Lowest pressure recorded at HKO
香港天文台錄得的最低氣壓
1007.7 hPa 百帕 (2017/09/24 14:16 HKT)

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
預測移動趨勢
Max. 10-min winds
中心最高十分鐘平均風速
2017/09/23 (SAT) 23:10 HKT SSE 570 km WNW at 25 km/h 45 km/h (25 knots, TD)
2017/09/24 (SUN) 19:20 HKT SW 520 km WNW at 22 km/h 45 km/h (25 knots, TD)

Figure 圖:

(Track figure courtesy of Lorenzo. Data from HKO. 鳴謝 Lorenzo 提供路徑圖,資料取自天文台)

TC Track

Percentile Ranks 百分等級:

Percentile ranks are only available for cyclones that necessitated at least the No. 3 Strong Wind Signal. 百分等級只適用於曾令天文台發出三號強風信號 (或更高) 的熱帶氣旋。

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:

TC Track

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)

Tropical depression 22W becomes the sixth tropical cyclone to affect Hong Kong this year. A patch of convections developed in northern South China Sea on September 23. The JTWC issued a tropical cyclone formation alert at 8 pm, while the HKO upgraded the system into tropical depression status at 11 pm. A broad subtropical ridge was covering southern China at that time, and the system was forecast to move west-northwest towards Hainan Island or Leizhou Peninsula.

The JTWC upgraded the system at 2 am September 24, giving it the storm number 22W. The storm was under strong vertical wind shear and most of its convections were displaced to the southwest. 22W maintained a generally westward motion throughout the morning of September 24, with minimal change in intensity.

22W made landfall near Wanning, Hainan at 9 pm September 24. The storm turned west-northwest after landfall and crossed Hainan overnight. It entered the Gulf of Tonkin near 3 am September 25 and made a second landfall in northern Vietnam in the early afternoon, before weakening into an area of low pressure that night.

熱帶低氣壓 22W 成為本年第六個影響香港的熱帶氣旋。9 月 23 日,一團對流雲帶於南海北部發展,聯合颱風警報中心於當晚 8 時對其發出熱帶氣旋形成警報。香港天文台於晚上 11 時將該系統升格為熱帶低氣壓。當時,一道廣闊副熱帶高壓脊正覆蓋華南,預料該系統將向西北偏西移動,大致趨向海南島或雷州半島一帶。

聯合颱風警報中心於 24 日上午 2 時將該對流雲帶升格為熱帶低氣壓,並給予風暴編號 22W。受較強垂直風切變影響,22W 大部分對流被切離至其西南方。風暴於 24 日上午以偏西方向移動,而強度則沒大變化。

22W 於 24 日下午 9 時左右登陸海南萬寧,並於登陸後向西北偏西移動,於午夜時份橫過海南島。風暴於 25 日上午約 3 時進入北部灣,隨後於下午早段登陸越南北部,繼而於當晚減弱為低壓區。

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

Link to relevant HKO weather report bulletins: 23/9 24/9
香港天文台相關天氣報告連結23/9 24/9

The HKO issued the #1 Standby Signal at 11:10 pm September 23, the same time as the agency's upgrade of the system into a tropical depression. 22W was at that time 570 km south-southeast of Hong Kong and was not expected to come closer than 300 km from the territory. The HKO therefore mentioned that higher signals were likely not needed.

Winds in the territory were generally the strongest in the small hours and morning of September 24; strong easterly winds were recorded in offshore areas such as Cheung Chau, Green Island, Tai Mei Tuk, Tap Mun and Waglan Island, and on high ground such as Tate's Cairn. 22W was the closest to Hong Kong near 9 am when it passed about 430 km to the south-southwest. The weather was unstable, with showers at times.

Local winds declined in the afternoon as 22W's distance to Hong Kong increased gradually. The #1 Standby Signal was cancelled at 7:20 pm September 24 when the storm was 520 km southwest of Hong Kong. Nevertheless, winds in some areas remained strong at times. The HKO thus issued the Strong Monsoon Signal at 9:45 pm; it was in effect until 5:40 am the next day.

The weather in Hong Kong improved on September 25, with some sunny periods during the day.

香港天文台於 9 月 23 日下午 11 時 10 分升格 22W 為熱帶低氣壓,同時發出一號戒備信號。當時 22W 位於香港東南偏南約 570 公里,預計會於本港 300 公里外掠過,因此天文台表示發出更高信號機會較低。

本港風勢於 24 日凌晨及早上最為強烈,其中離岸地區如長洲、青洲、大美督、塔門及橫瀾島,以及高地如大老山吹強風。22W 於上午約 9 時最接近本港,並於香港西南偏南約 430 公里處。當天天氣不穩定,間中有驟雨。

隨著 22W 與本港的距離於下午增加,風勢逐漸放緩,天文台遂於 24 日下午 7 時 20 分取消一號戒備信號,當時 22W 於香港西南約 520 公里。雖然風暴遠離,但部分地區仍間中吹強風。天文台於下午 9 時 45 分發出強烈季候風信號,至翌日上午 5 時 40 分取消。

本港天氣於 25 日改善,當日日間部分時間有陽光。

Image Gallery 圖片庫

Figure 1 - Steering flow chart at 8 pm September 23
圖 1 - 9 月 23 日下午 8 時之駛流場圖

Figure 2 - Satellite image of 22W at formation
圖 2 - 22W 形成時之衛星雲圖

Figure 3 - HKO's forecast track in the small hours of September 24
圖 3 - 香港天文台於 9 月 24 日凌晨之預測路徑圖

Figure 4 - Wind field analysis at 9:37 am September 24
圖 4 - 9 月 24 日上午 9 時 37 分之風場掃描圖

Figure 5 - Satellite image of 22W at 10 am September 24
圖 5 - 22W 於 9 月 24 日上午 10 時之衛星雲圖

Figure 6 - Wind speed time series at Cheung Chau and Waglan Island (top to bottom) on September 24
圖 6 - 長洲及橫瀾島 (上至下) 於 9 月 24 日的風速時間序列圖

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

(Except for special cases, this section is not available for cyclones that only necessitated the Standby Signal 除非特別情況,否則此部只當氣旋令天文台發出三號或更高信號時提供)

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
17092312 179N1160E 025
17092318 182N1146E 025
17092400 184N1131E 030
17092406 186N1119E 030
17092412 189N1108E 030
17092418 195N1095E 030
17092500 201N1082E 030
17092506 209N1071E 030
17092512 217N1060E 025

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)

Station Maximum Gust Maximum Hourly Mean Wind
Direction Speed
(km/h)
Date/Month Time Direction Speed
(km/h)
Date/Month Time
Central Pier E 54 24/9 08:46 E 31 24/9 10:00
Cheung Chau ESE 85 24/9 05:30 ESE 47 24/9 16:00
ESE 47 24/9 17:00
Cheung Chau Beach E 77 24/9 05:31 ENE 49 24/9 09:00
Green Island E 62 24/9 10:26 ENE 40 24/9 03:00
Hong Kong International Airport ESE 52 24/9 14:39 ESE 34 24/9 15:00
Kai Tak NE 54 24/9 09:24 E 30 24/9 15:00
King's Park E 51 24/9 05:54 ESE 22 24/9 15:00
Lau Fau Shan E 47 24/9 15:27 E 22 24/9 10:00
E 22 24/9 11:00
Peng Chau E 51 24/9 10:29 E 36 24/9 10:00
Ping Chau ENE 36 24/9 08:17 E 7 24/9 08:00
E 7 24/9 09:00
Sai Kung ENE 56 24/9 06:19 ENE 30 24/9 10:00
Sha Chau SE 47 24/9 14:40 SE 31 24/9 18:00
Sha Lo Wan SE 51 24/9 17:36 E 23 24/9 10:00
Sha Tin SE 43 24/9 11:58 SE 14 24/9 14:00
Shek Kong E 47 24/9 09:53 E 22 24/9 10:00
Star Ferry (Kowloon) E 56 24/9 10:19 E 27 24/9 15:00
Ta Kwu Ling ENE 47 24/9 10:48 E 16 24/9 14:00
E 16 24/9 16:00
Tai Mei Tuk E 67 24/9 17:29 ENE 36 24/9 11:00
Tai Mo Shan ESE 88 24/9 11:07 ESE 58 24/9 11:00
Tai Po Kau ESE 49 24/9 17:33 E 31 24/9 09:00
E 31 24/9 10:00
Tap Mun* E 96 24/9 10:23 E 45 24/9 13:00
Tate's Cairn ESE 87 24/9 10:11 E 45 24/9 08:00
Tseung Kwan O ESE 41 24/9 12:56 NE 13 24/9 09:00
Tsing Yi Shell Oil Depot SE 52 24/9 13:37 SE 19 24/9 15:00
Tuen Mun Government Offices SE 51 24/9 15:54 SE 22 24/9 15:00
Waglan Island E 79 24/9 05:04 ENE 56 24/9 08:00
Wetland Park ENE 31 24/9 10:08 E 14 24/9 15:00
Wong Chuk Hang E 52 24/9 07:44 E 20 24/9 11:00
E 52 24/9 07:50  

*The old wind station on the rooftop of Tap Mun Police Post is replaced by the new Tap Mun station on July 6, 2017.
*新塔門測風站在 2017 年 7 月 6 日取代在塔門警崗屋頂的舊測風站。

Table 3: Rainfall (in millimetres) contributed by 22W 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)

Station 24-Sep Total rainfall (mm)
Hong Kong Observatory
5.6
5.6
Hong Kong International Airport (HKA)
7.8
7.8
Cheung Chau (CCH)
10.0
10.0
H23 Aberdeen
10.0
10.0
N05 Fanling
19.5
19.5
N13 High Island
21.5
21.5
K04 Jordan Valley
6.0
6.0
N06 Kwai Chung
3.5
3.5
H12 Mid Levels
10.0
10.0
N09 Sha Tin
7.0
7.0
H19 Shau Kei Wan
8.0
8.0
SEK Shek Kong
8.5
8.5
K06 So Uk Estate
6.0
6.0
R31 Tai Mei Tuk
25.0
25.0
R21 Tap Shek Kok
2.5
2.5
TMR Tuen Mun Reservoir
1.4
1.4
N17 Tung Chung
5.0
5.0

Last Accessed 最近訪問日期: Fri Nov 15 2019 05:35:32 HKT
Last Modified 最近修訂日期: Thu Nov 08 2018

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