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TC Watch > Selected TC Review > 200821W (HIGOS) [Refresh]

200821W (HIGOS) - Profile

(First issued on October 30th, 2008, final version issued on November 6th, 2008)

Brief profile of HIGOS:

JTWC number 21W
International number 0817
Period of existence 29 September, 2008 14 HKT to 4 October, 2008 14 HKT*
Lifetime 5.00 days*
Maximum 1-minute wind (JTWC) 45 knots
Minimum pressure (JTWC) 989 hPa
Highest TC signal by HKO (if applicable) 1 (Standby Signal)
Closest point of approach by HKO (if applicable) W 330 km (real-time warning**) / N/A (TC report)
Time of closest approach by HKO (if applicable) 5 October, 2008 02 HKT (real-time warning**) / N/A (TC report)
Lowest pressure recorded at HKO (if applicable) 1007.7 hPa (4 October, 2008 17:00 to 17:01 HKT)

*Based on JTWC bulletins.
**Based on the final South China Coastal Waters bulletin before downgrading HIGOS into an area of low pressure.

TC signals for Hong Kong & Track:

Table:

Signal
Date and time
Distance from HK
Predicted movement
Max. 10-min winds
2008/10/02 (THU) 19:30 HKT
S 690 km
NW/WNW at 20 km/h
56 km/h (30 knots, TD)
2008/10/04 (SAT) 22:30 HKT
WSW 350 km
N/NNE at 8 km/h
56 km/h (30 knots, TD)

Figure: (Track courtesy of Lorenzo. Data from HKO.)

TC Track

IR imagery animation 紅外線雲圖動畫:

TC track from HKWW:

TC Track

TC tracks from HKO:

TC Track

TC Track

Past HKWW Bulletins on HIGOS

Please click here for bulletins on HIGOS.

Storm Formation and Development

A disturbance 99W developed off the eastern Philippine coast on September 29th. Initial forecasts called for a retreat of the subtropical ridge anchored northeast of the system, leading to gradual recurvature in the South China Sea towards northeastern South China Sea. However it turned out that the ridge was once again stronger than expected and this system moved much more west than forecast.

The JTWC upgraded this system into a tropical depression on September 29th, giving it the temporary number 21W. 21W intensified gradually into a tropical storm on September 30th, and the JMA upgraded it to tropical storm status at 08 HKT. The name HIGOS was assigned to this storm together with the upgrade.

HIGOS reached maximum intensity in the middle of September 30th while moving northwestward, after which it made landfall at eastern Philippines. It weakened considerably while crossing the islands, and at one point it was so disorganized that convective cloud bands were not discernible on satellite images. Low-level steering continued to guide HIGOS towards the west, and HIGOS' centre just skirted past Manila

Figure 1 - Initial track by various agencies

Figure 2 - Steering chart at 14 HKT, September 30th (HIGOS was about to make landfall at eastern Philippines at that time)

Figure 3 - Visible imagery of HIGOS at 14:30 HKT, October 1st

Figure 4 - IR image of HIGOS earlier at 02:00 HKT, October 1st. Note HIGOS' loose cloud bands.

Entering South China Sea

HIGOS entered South China Sea on late October 1st. Since it has been keeping a rather westward track, most major agencies shifted the forecast track west, predicting a landfall in the proxiimity of Hong Kong. A weakness started to develop to the north of the system, but the weakness did not amplify enough to induce poleward movement until October 3rd.

Convections improved slightly on the next day as the storm progressed west-northwestward on October 2nd. With the perception of possible adverse weather two to three days later, the Observatory issued the Number 1 Standby Signal [issuance document here] at 19:30 HKT that day, when HIGOS was about 690 kilometres south of Hong Kong.

Figure 5 - Steering chart at 14 HKT, October 2nd

Figure 6 - Forecast track by various agencies, predicting a landfall near Hong Kong

Figure 7 - Hong Kong Observatory's direct hit forecast

Higos' Landfalls

HIGOS continued its WNW track and was edging Hainan Island. The Hong Kong Observatory upgraded HIGOS into a tropical storm at 10 HKT on October 3rd as its structure improved. HIGOS finally started to decelerate in the latter part on October 3rd as the weakness in the subtropical ridge north of the storm deepened.

Just before reaching Hainan, HIGOS turned due north towards western Guangdong. The Observatory still predicted a pretty near closest point of approach (CPA), but has now shifted this CPA to north of Hong Kong with weakened intensity. HIGOS made landfall at the eastern tip of Hainan Island at 23 HKT that day.

Land interaction caused HIGOS to weaken and its cloud bands became less organized. In response, the Observatory downgraded HIGOS into a tropical depression at 10 HKT on October 4th. HIGOS moved slowly on that day and finally made its second landfall at Wuchuan City (吳川市) at 17 HKT the same day. Since HIGOS did not show signs of recurving to the east and has already landed, the Observatory cancelled the Standby Signal at 22:30 HKT that night.

Figure 8 - RADAR image at 21:32 HKT on October 3rd. At that time HIGOS was about to make landfall at Hainan.

Subsequent Track and Effects on Hong Kong after Landfall

However, instead of moving into land and dissipate, HIGOS turned ENE and moved along the coast on October 5th. From RADAR images by China, HIGOS' rainbands tightened and its structure improved a bit. Affected by the rainbands, occasional heavy rain was observed in Hong Kong early that day and the Amber Rainstorm Warning was in force from 08:50 to 11:30 HKT. Later in the afternoon, force 7 winds and a minimum pressure of 1000.5 hPa was recorded at Shangchuan Dao. As HIGOS (or HIGOS' remnants) moved further eastward, southerly winds in Hong Kong started to pick up just before dusk. The Hong Kong Observatory issued the Strong Monsoon Signal [issuance document here] at 17:45 HKT (although the winds were hardly contributed by monsoon) as HIGOS' rainbands swept past Hong Kong. The Observatory also mentioned in their Thunderstorm Warning bulletin that gusts of 100 km/h or more would affect the territory. The Amber Rainstorm Warning was issued for the second time on that day at 18:15 HKT as Hong Kong was hit by another major rainband; the signal was in force until 20:40 HKT.

The cyclonic system turned NE as it reached Macau, and was just tens of kilometres away from Hong Kong that night. Winds turned clockwise to southwesterlies at that time. It finally moved further inland in the early hours of October 6th and tranformed completely into an extratropical cyclone later that day.

Mr. Lam Chiu-ying, the Director of the Observatory, mentioned in his blog that HIGOS' remnants developed frontal characteristics which accounted for the temperature difference between the two sides of the cyclonic system (and also explained why Hong Kong experienced a drop in temperature in early October 6th). As a temperate cyclone, the potential energy from the temperature difference of air parcels converted into kinetic energy that fuelled the storm and led to its temporary intensification on October 5th. He mentioned that since the situation was "a temperate depression coming about in the background of the monsoon", the Strong Monsoon Signal was the only rational way to represent this event, and this set a precedent for similar episodes in the future. (However, it remained arguable whether or not the Strong Monsoon Signal was really appropriate for the situation, as winds from a genuine monsoon and that from a cyclonic system could have different characteristics and most importantly, imply different precautionary measures to be performed.)

Figure 9 - Visible imagery of HIGOS at 14:30 HKT, October 5th

Figure 10 - RADAR image at 11:55 HKT on October 5th. HIGOS appeared to be gaining strength at that time.

Figure 11 - Pressure time series at Shangchuan Dao between 14 HKT, October 4th and 20 HKT, October 5th

Figure 12 - Weather elements around Hong Kong, 18:30 HKT on October 5th

Figure 13 - Wind direction in various parts within Dongguan City. Note that the centre of the cyclonic system was near the top left corner of the plot.

Figure 14 - The Observatory's claim on HIGOS' frontal features

Figure 15 - The Observatory's preliminary track of HIGOS near Hong Kong

Winds Recorded at Reference Stations

(Except for special cases, this section is not available for cyclones that only necessitated the Standby Signal)

Charts and Figures

Table 1: Track data from HKWW:

YYMMDDZZ Lat Long Wind
08092906 092N1313E 025
08092912 089N1296E 035
08092918 099N1277E 040
08093000 110N1268E 045
08093006 120N1260E 045
08093012 131N1237E 040
08093018 135N1233E 035
08100100 139N1230E 035
08100106 141N1220E 035
08100112 145N1208E 035
08100118 147N1190E 035
08100200 150N1178E 035
08100206 160N1163E 035
08100212 162N1145E 035
08100218 164N1134E 035
08100300 174N1120E 035
08100306 184N1110E 035
08100312 190N1110E 035
08100318 199N1110E 030
08100400 202N1109E 030
08100406 212N1109E 030
08100412 215N1109E 030
08100418 216N1110E 025
08100500 218N1119E 025
08100506 219N1124E 025
08100509 221N1133E 030
08100512 228N1137E 030
08100515 230N1137E 025

Table 2: Maximum gust and 60-minute average wind speed recorded in Hong Kong from HKO:

Maximum Gust Maximum Hourly Wind
Station Direction Speed (km/h) Date/Month Time Direction Speed (km/h) Date/Month Time
Bluff Head (Stanley) NNE 56 3/10 23:57 NE 34 3/10 20:00
Central Pier ENE 45 3/10 13:45 E 31 3/10 06:00
          E 31 4/10 01:00
Cheung Chau E 62 4/10 03:10 E 38 4/10 08:00
Cheung Sha Wan  NE 34 3/10 12:17 ENE 13 3/10 09:00
Green Island ENE 65 3/10 08:23 ENE 51 3/10 13:00
  ENE 65 3/10 12:29        
Hong Kong International Airport S 54 4/10 18:05 SE 31 4/10 14:00
Kai Tak ENE 54 3/10 13:36 E 30 3/10 20:00
King's Park  E 41 3/10 15:07 E 20 3/10 13:00
Lau Fau Shan E 49 3/10 12:17 SSE 31 4/10 15:00
Ngong Ping SW 110  4/10 22:11 E 59 4/10 01:00
North Point E 47 4/10 01:24 E 25 3/10 17:00
          E 25 4/10 01:00
Peng Chau ENE 52  3/10 14:04 ENE 36 4/10 01:00
  ENE 52  3/10 14:08        
Ping Chau E 43  3/10 13:57 E 16 3/10 14:00
Sai Kung  ENE 45 3/10 19:55 ENE 31 3/10 20:00
Sha Chau SSE 54  4/10 16:22 SSE 34 4/10 17:00
Sha Lo Wan SE 49 4/10 22:12 E 27 3/10 15:00
Sha Tin ESE 31 4/10 09:43 SE 16 4/10 14:00
          SE 16 4/10 16:00
Shek Kong E 49 3/10 12:58 E 23 3/10 15:00
Star Ferry (Kowloon) ESE 43 3/10 18:44 E 25 3/10 13:00
          ESE 25 3/10 15:00
Ta Kwu Ling  SE 36 4/10 14:35 SE 14 4/10 15:00
Tai Mei Tuk E 52 3/10 20:08 E 34 3/10 19:00
Tai Mo Shan E 81 4/10 03:06 E 54 4/10 03:00
Tate's Cairn  - 70 4/10 01:08 - 41 3/10 15:00
Tsak Yue Wu E 36 3/10 13:20 ENE 13 3/10 11:00
          ENE 13 4/10 00:00
Tseung Kwan O E 38 3/10 12:04 NNE 14 3/10 09:00
Tsing Yi Shell Oil Depot SE 40 4/10 13:48 ESE 23 4/10 19:00
  SE 40 4/10 13:49        
Tuen Mun Government Offices ESE 47 4/10 07:13 SE 22 4/10 22:00
Waglan Island E 56 3/10 14:35 E 49 3/10 23:00
  E 56 3/10 18:18        
  E 56 3/10 18:31        
Wetland Park SSE 40  4/10 15:42 SSE 20 4/10 16:00
Wong Chuk Hang E 58 4/10 00:44 E 25 3/10 13:00
          E 25 4/10 01:00

Table 3: Rainfall contributed by HIGOS from HKO (figures in brackets are based on incomplete hourly data):

Station 2-Oct 3-Oct 4-Oct 5-Oct Total
Hong Kong  Observatory 3.0 2.4 14.0 122.6 142.0
Cheung Chau (CCH) 4.5 0.0 8.5 114.5 127.5
Hong Kong International Airport (HKA) Trace 0.2 4.5 83.1 87.8
H12 Mid Levels [2.0] [3.0] [21.0] [101.5] [127.5]
H19 Shau Kei Wan 2.5 3.5 [7.0] 101.0 [114.0]
H21 Repulse Bay 3.0 3.5 [6.0] [84.0] [96.5]
K04 Jordan Valley [0.5] [0.0] [22.0] [29.5] [52.0]
N05 Fanling 0.0 0.0 [5.5] 113.5 [119.0]
N06 Kwai Chung 1.5 1.5 [21.5] 131.5 [156.0]
N09 Sha Tin 0.0 1.5 [11.5] 107.5 [120.5]
N12 Yuen Long 0.0 0.0 [11.0] 121.5 [132.5]
N13 High Island 0.0 1.5 [8.0] 66.5 [76.0]
N17 Tung Chung 0.0 3.5 [9.0] 138.5 [151.0]
R21 Tap Shek Kok 0.0 0.0 4.5 68.5 73.0
R26 Shek Kong 0.0 1.0 11.0 [94.0] [106.0]
R31 Tai Mei Tuk 0.0 0.0 33.0 97.5 130.5

Last Accessed: Mon Aug 26 2019 02:42:46 HKT
Last Modified: Sun Oct 02 2016

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