NESAT made landfall at northern Vietnam this afternoon. At 20 HKT, NESAT was centred about 50 km (25 NM) ESE of Hanoi. All tropical cyclone signals were cancelled at 06:25 HKT today.
NESAT is now at the Qiongzhou Strait. At 20 HKT, NESAT was centred about 490 km (270 NM) WSW of Hong Kong. The Strong Wind Signal was issued at 16:10 HKT, replacing the #8 Southeast Gale or Storm Signal.
A finger of the subtropical ridge is still seen in southern China. NESAT is expected to move W to WNW across the Gulf of Tonkin.
副熱帶高壓脊延伸部分仍然存在於華南地區。預料納沙將向西至西北偏西移動，橫過北部灣。
Intensity
Analysis 強度分析
Current T-number: T4.0/4.5/W0.5/03 HRS
NESAT has weakened slightly in the past 6 hours. The storm will continue to weaken due to land interaction. Rapid weakening will occur after NESAT makes landfall at Vietnam.
現時的 T 號碼: T4.0/4.5/W0.5/03 HRS
納沙過去 6 小時稍為減弱。納沙將因地形影響而繼續減弱，登陸越南後減弱速度加快。
Effects on
Hong Kong 對香港的影響
Strong SE winds are affecting parts of the territory. Winds will gradually subside, but there may still be squally showers overnight.
本港部分地區受東南強風影響。預料風勢將逐漸緩和，但今晚仍會有狂風驟雨。
Next Update
下次更新
23 HKT, 2011/09/30 (Fri 五) or earlier 或更早
Other Images
其他圖像
JTWC Track 聯合颱風警報中心路徑圖
JMA Track 日本氣象廳路徑圖
HKO Satellite 香港天文台衛星圖
HKO Track 香港天文台路徑圖
Probabilities
of TC Signals from HKO 香港天文台 (已) 發出 / 取消熱帶氣旋警告信號的機率
Signal 信號
t+12
t+24
t+36
t+48
t+60
t+72
Standby 戒備 #1 (Cnl. 取消)
Very High 極高
Very High 極高
Very High 極高
Very High 極高
Very High 極高
Very High 極高
Strong Wind 強風 #3 (Cnl. 取消)
Very High 極高
Very High 極高
Very High 極高
Very High 極高
Very High 極高
Very High 極高
Gale/Storm 烈或暴風 #8
G/S Incr. 烈或暴風增強 #9
Hurricane 颶風 #10
Notes 註:
1) For issuance, "Signal" column represents having issued that signal or above. 有關發出機率，首欄指已發出該信號或更高信號。
2) "Low" = Probability from 5 to 20 per cent; "Medium" = 20 to 50%; "High" = 50 to 80%; "V High" = 80% or above.
"低" = 5% - 20% 的機率; "中等" = 20 - 50%; "高" = 50 - 80%; "極高" = 80% 或以上。
NESAT is now moving away from Hong Kong. At 14 HKT, NESAT was centred about 420 km (230 NM) SW of Hong Kong. The #8 Gale or Storm Signal will be replaced by the #3 Strong Wind Signal shortly.
A finger of the subtropical ridge is still seen in southern China. NESAT is expected to move WNW across the Qiongzhou Strait, after which it will enter the Gulf of Tonkin.
副熱帶高壓脊延伸部分仍然存在於華南地區。預料納沙將向西北偏西移動，橫過瓊州海峽並進入北部灣。
Intensity
Analysis 強度分析
Current T-number: T4.5/4.5/S0.0/03 HRS
NESAT is expected to weaken due to land interaction. Rapid weakening will occur after NESAT makes landfall at Vietnam.
現時的 T 號碼: T4.5/4.5/S0.0/03 HRS
納沙將因地形影響而開始減弱，並於登陸越南後快速減弱。
Effects on
Hong Kong 對香港的影響
Strong to gale force SE winds are affecting Hong Kong with frequent squally showers. Winds are expected to subside gradually but occasional gusts could still be strong.
本港仍受強風至烈風程度東南風影響，且有頻密狂風驟雨。預料風勢將逐漸緩和，但陣風仍然猛烈。
Next Update
下次更新
23 HKT, 2011/09/29 (Thu 四) or earlier 或更早
Other Images
其他圖像
JTWC Track 聯合颱風警報中心路徑圖
JMA Track 日本氣象廳路徑圖
HKO Satellite 香港天文台衛星圖
HKO Track 香港天文台路徑圖
Probabilities
of TC Signals from HKO 香港天文台 (已) 發出 / 取消熱帶氣旋警告信號的機率
Signal 信號
t+12
t+24
t+36
t+48
t+60
t+72
Standby 戒備 #1 (Cnl. 取消)
High 高
Very High 極高
Very High 極高
Very High 極高
Very High 極高
Very High 極高
Strong Wind 強風 #3 (Cnl. 取消)
High 高
Very High 極高
Very High 極高
Very High 極高
Very High 極高
Very High 極高
Gale/Storm 烈或暴風 #8 (Cnl. 取消)
Very High 極高
Very High 極高
Very High 極高
Very High 極高
Very High 極高
Very High 極高
G/S Incr. 烈或暴風增強 #9
Hurricane 颶風 #10
Notes 註:
1) For issuance, "Signal" column represents having issued that signal or above. 有關發出機率，首欄指已發出該信號或更高信號。
2) "Low" = Probability from 5 to 20 per cent; "Medium" = 20 to 50%; "High" = 50 to 80%; "V High" = 80% or above.
"低" = 5% - 20% 的機率; "中等" = 20 - 50%; "高" = 50 - 80%; "極高" = 80% 或以上。
NESAT is now closest to Hong Kong. At 11 HKT, NESAT was centred about 360 km (200 NM) SW of Hong Kong. The Observatory issued the #8 Southeast Gale or Storm Signal at 04:40 HKT.
A finger of the subtropical ridge is still seen in southern China. NESAT is expected to move WNW towards Leizhou Peninsula and northern Hainan Island, after which it will enter the Gulf of Tonkin.
Current T-number: T4.5/4.5/S0.0/09 HRS
NESAT is expected to maintain its current intensity until landfall.
現時的 T 號碼: T4.5/4.5/S0.0/09 HRS
納沙將於登陸前大致維持強度。
Effects on
Hong Kong 對香港的影響
NESAT is now closest to Hong Kong. Widespread gale force E/SE winds are currently observed in Hong Kong, and winds will remain strong in the next few hours. The #8 Gale or Storm Signal is expected to remain in force at least until afternoon. Occasional heavy squally showers will continue to affect Hong Kong, and wind direction will gradually change to the southeast.
NESAT took a NW track in the past 6 hours. At 02 HKT, NESAT was centred about 380 km (210 NM) S of Hong Kong. The Observatory will consider higher tropical cyclone warning signals in the next couple of hours.
The subtropical ridge has extended to the east of NESAT, and is contributing to the increased northward track component. NESAT is expected to move WNW towards Leizhou Peninsula and northern Hainan Island, after which it will enter the Gulf of Tonkin.
Current T-number: T4.5/4.5/S0.0/06 HRS
NESAT's structure improved and cloud banding becomes increasingly symmetric. Divergence near NESAT is good while wind shear is at a moderate level. Slight intensification before landfall is still possible.
現時的 T 號碼: T4.5/4.5/S0.0/06 HRS
納沙結構有所改善，雲捲漸趨對稱。納沙附近輻散良好，但風切於中等水平。預料納沙或會在登陸前稍作增強。
Effects on
Hong Kong 對香港的影響
NESAT has travelled more northward than predicted. Due to its wide wind radii, gale force winds are expected in Hong Kong early today, with winds coming in from the east. Squally showers will also be observed. NESAT is expected to be closest to Hong Kong this morning.
Probabilities
of TC Signals from HKO 香港天文台 (已) 發出 / 取消熱帶氣旋警告信號的機率
The Observatory will consider higher signals in the next couple of hours. It is very likely that the #8 Gale or Storm Signal will be issued near dawn today.
天文台將於未來數小時考慮改發更高信號。預計天文台很可能於破曉時份發出八號烈風或暴風信號。
Signal 信號
t+12
t+24
t+36
t+48
t+60
t+72
Standby 戒備 #1 (Cnl. 取消)
Low 低
High 高
Very High 極高
Very High 極高
Very High 極高
Strong Wind 強風 #3 (Cnl. 取消)
Medium 中等
High 高
Very High 極高
Very High 極高
Very High 極高
Gale/Storm 烈或暴風 #8
High 高
Low 低
G/S Incr. 烈或暴風增強 #9
Hurricane 颶風 #10
Notes 註:
1) For issuance, "Signal" column represents having issued that signal or above. 有關發出機率，首欄指已發出該信號或更高信號。
2) "Low" = Probability from 5 to 20 per cent; "Medium" = 20 to 50%; "High" = 50 to 80%; "V High" = 80% or above.
"低" = 5% - 20% 的機率; "中等" = 20 - 50%; "高" = 50 - 80%; "極高" = 80% 或以上。
NESAT moved WNW in general in the past 24 hours, with increased northward track component in the past 6 hours. At 20 HKT, NESAT was centred about 460 km (250 NM) S of Hong Kong. The Observatory issued the Standby Signal at 22:40 HKT last night and replaced it by the Strong Wind Signal at 17:20 today.
The subtropical ridge north of NESAT has weakened but is still exerting considerable influence on the storm. NESAT is expected to move WNW towards Leizhou Peninsula and Hainan Island, after which it will enter the Gulf of Tonkin.
Current T-number: T4.5/4.5/D0.5/24 HRS
NESAT's structure improved and cloud banding becomes increasingly symmetric. Divergence near NESAT is good while wind shear is at a moderate level. Slight intensification before landfall is still possible.
現時的 T 號碼: T4.5/4.5/D0.5/24 HRS
納沙結構有所改善，雲捲漸趨對稱。納沙附近輻散良好，但風切於中等水平。預料納沙或會在登陸前稍作增強。
Effects on
Hong Kong 對香港的影響
NESAT has wide wind radii. Winds in Hong Kong strengthened considerably after the issuance of the Strong Wind Signal. Currently gale force NE/ENE winds are blowing at some offshore areas like Cheung Chau and Waglan Island, and strong winds are observed at some other locations. Winds are expected to remain strong overnight with a gradual change in direction to the E/SE. There will also be heavy squally showers. NESAT is expected to be closest to Hong Kong tomorrow morning.
NESAT made landfall at Luzon early this morning and entered the South China Sea in the afternoon. At 20 HKT, NESAT was centred about 780 km (420 NM) SE of Hong Kong.
NESAT is in the southern periphery of the subtropical ridge. A steady WNW movement is predicted and NESAT is expected to make landfall at Hainan Island on Thursday. Track speed should remain at around 20 km/h prior to landfall.
Current T-number: T4.0/4.5/W0.5/24 HRS
NESAT's eye was destroyed as it travelled on land today, but tight convections are still indicative of its typhoon strength. With low to moderate shear and warm seas NESAT should be able to intensify before landfall.
現時的 T 號碼: T4.0/4.5/W0.5/24 HRS
納沙登陸呂宋，其風眼於雲圖上消失，但其螺旋雲帶仍較為緊密，顯示其達颱風強度。納沙將經過溫暖的海域，風切屬低至中等，預料它能在登陸前增強。
Effects on
Hong Kong 對香港的影響
Weather in Hong Kong will deteriorate later tomorrow with strengthening easterly winds and squally showers. NESAT will be closest to Hong Kong on Thursday, and winds offshore and on high grounds may reach gale force.
The subtropical ridge has further extended, and NESAT is moving WNW in its southern periphery. Model forecasts generally call for a steady WNW movement along the ridge's south to southwestern periphery and track the storm towards northern Hainan and Leizhou Peninsula, with GFS depicting a more northward movement. This bulletin favours a steady track towards WNW and expects the storm to make landfall somewhere near Leizhou Peninsula on Friday.
Current T-number: T4.5/4.5/D0.5/24 HRS
NESAT's eye becomes more prominent but is still cloud-filled. The storm is expected to strengthen slightly before making landfall, after which a temporary drop in intensity should be observed. NESAT should be able to regain strength in the warm South China Sea.
現時的 T 號碼: T4.5/4.5/D0.5/24 HRS
納沙的風眼變得更為明顯，但仍然被雲填滿。預料納沙將於登陸前稍為增強，隨後強度暫時下降。納沙應能在溫暖的南海中再度增強。
Effects on
Hong Kong 對香港的影響
As NESAT edges closer to Hong Kong towards the latter part of this week, weather is expected to deteriorate with strengthening easterly winds.
隨著納沙於本周較後時間逐步靠近本港，預料本港天氣將於周中開始轉壞，東風將會加強。
Next Update
下次更新
23 HKT, 2011/09/27 (Tue 二) or earlier 或更早
Other Images
其他圖像
JTWC Track 聯合颱風警報中心路徑圖
JMA Track 日本氣象廳路徑圖
HKO Satellite 香港天文台衛星圖
HKO Track 香港天文台路徑圖
Probabilities
of TC Signals from HKO 香港天文台 (已) 發出 / 取消熱帶氣旋警告信號的機率
Signal 信號
t+12
t+24
t+36
t+48
t+60
t+72
Standby 戒備 #1
Low 低
High 高
Very High 極高
Very High 極高
High 高
Strong Wind 強風 #3
Low 低
Medium 中等
High 高
High 高
Gale/Storm 烈或暴風 #8
Medium 中等
Low 低
G/S Incr. 烈或暴風增強 #9
Hurricane 颶風 #10
Notes 註:
1) For issuance, "Signal" column represents having issued that signal or above. 有關發出機率，首欄指已發出該信號或更高信號。
2) "Low" = Probability from 5 to 20 per cent; "Medium" = 20 to 50%; "High" = 50 to 80%; "V High" = 80% or above.
"低" = 5% - 20% 的機率; "中等" = 20 - 50%; "高" = 50 - 80%; "極高" = 80% 或以上。
The subtropical ridge is firmly established north of NESAT, causing the latter to speed towards the west today. NESAT has decelerated slightly in the past 6 hours. It is expected that NESAT will move west in the southern periphery of the ridge, and turn to WNW as it reaches its southwestern periphery. The ridge appears to be stronger than predicted, and thus the forecast track is shifted westward.
Current T-number: T4.0/4.0/D1.0/24 HRS
NESAT intensified further today. In decent environment NESAT is expected to intensify in the next 36 hours, after which severe weakening will take place as NESAT traverses Luzon. NESAT should be able to re-intensify in South China Sea.
現時的 T 號碼: T4.0/4.0/D1.0/24 HRS
納沙今天進一步增強。在良好環境下，預料納沙將於未來 36 小時繼續增強，隨後因登陸呂宋而明顯減弱。納沙應能於南海裡再次增強。
Effects on
Hong Kong 對香港的影響
As NESAT edges closer to Hong Kong towards the latter part of this week, weather is expected to deteriorate with an increase in wind speed.
隨著納沙於本周較後時間逐步靠近本港，預料本港天氣將於周中開始轉壞，風勢加強。
Next Update
下次更新
23 HKT, 2011/09/26 (Mon 一) or earlier 或更早
Other Images
其他圖像
JTWC Track 聯合颱風警報中心路徑圖
JMA Track 日本氣象廳路徑圖
HKO Satellite 香港天文台衛星圖
HKO Track 香港天文台路徑圖
Probabilities
of TC Signals from HKO 香港天文台 (已) 發出 / 取消熱帶氣旋警告信號的機率
Signal 信號
t+12
t+24
t+36
t+48
t+60
t+72
Standby 戒備 #1
Medium 中等
Very High 極高
Strong Wind 強風 #3
Low 低
Gale/Storm 烈或暴風 #8
G/S Incr. 烈或暴風增強 #9
Hurricane 颶風 #10
Notes 註:
1) For issuance, "Signal" column represents having issued that signal or above. 有關發出機率，首欄指已發出該信號或更高信號。
2) "Low" = Probability from 5 to 20 per cent; "Medium" = 20 to 50%; "High" = 50 to 80%; "V High" = 80% or above.
"低" = 5% - 20% 的機率; "中等" = 20 - 50%; "高" = 50 - 80%; "極高" = 80% 或以上。
The subtropical ridge northeast of NESAT is now extending westward and covering areas north of the storm. This will allow NESAT to move west in the next 36 hours. By 48 hours NESAT will have reached the extended ridge's southwestern periphery and WNW movement will resume. Numerical model outputs from ECMWF, NGP and GFS are currently showing landfall between central and eastern Guangdong. A recurvature or abrupt turn to the north prior to landfall is deemed unlikely at this moment as the subtropical ridge axis is expected to remain rather north with no indication of the ridge extending at low latitudes.
Current T-number: T3.0/3.0/D1.0/24 HRS
NESAT's spiraling cloud bands become more compact today. Good divergence, high sea temperatures and low shear will all contribute to a steady strengthening of the system. The storm will suffer a loss of intensity near t+72 as it skirts or makes landfall over northern Luzon, but conditions in the South China Sea should be favourable for re-strengthening.
現時的 T 號碼: T3.0/3.0/D1.0/24 HRS
納沙之螺旋雲帶今天變得緊密。在良好輻散、高海溫和低垂直風切變的環境下，預料納沙將穩定增強。72 小時後，納沙掠過或登陸呂宋北部，強度將有所減低，但南海的環境應有利納沙再度增強。
Effects on
Hong Kong 對香港的影響
No threat to Hong Kong is expected within the next 72 hours.
納沙於未來的 72 小時將不會對香港構成任何影響。
Next Update
下次更新
23 HKT, 2011/09/25 (Sun 日) or earlier 或更早
Other Images
其他圖像
JTWC Track 聯合颱風警報中心路徑圖
JMA Track 日本氣象廳路徑圖
HKO Satellite 香港天文台衛星圖
HKO Track 香港天文台路徑圖
Probabilities
of TC Signals from HKO 香港天文台 (已) 發出 / 取消熱帶氣旋警告信號的機率
20W is currently situated in the southwestern tip of the subtropical ridge, and is moving NW. The ridge is expected to extend westward, placing 20W to its south. 20W will thus move WNW turning to W in the next 72 hours.
Current T-number: T2.0/2.0/INT OBS
20W is in a region with low vertical wind shear and decent outflow. As the storm moves west, it will track across seas with temperatures in excess of 30 degrees. Intensification at or above climatological rate is expected within the next 72 hours.
Active Tropical Cyclone(s) 正活躍之熱帶氣旋
