從定位及掃描圖來看19S的中心已經至少半裸,MFR也於1912Z發出最後警告

WTIO30 FMEE 191236
RSMC / TROPICAL CYCLONE CENTER / LA REUNION
TROPICAL CYCLONE FORECAST WARNING (SOUTH-WEST INDIAN OCEAN)
0.A WARNING NUMBER: 8/12/20182019
1.A MODERATE TROPICAL STORM 12 (SAVANNAH)
2.A POSITION 2019/03/19 AT 1200 UTC:
WITHIN 20 NM RADIUS OF POINT 18.4 S / 85.2 E
(EIGHTEEN DECIMAL FOUR DEGREES SOUTH AND
EIGHTY FIVE DECIMAL TWO DEGREES EAST)
MOVEMENT: WEST 6 KT
3.A DVORAK ANALYSIS: NIL
4.A CENTRAL PRESSURE: 1002 HPA
5.A MAX AVERAGE WIND SPEED (10 MN): 35 KT
RADIUS OF MAXIMUM WINDS (RMW): 46 KM
6.A EXTENSION OF WIND BY QUADRANTS (KM):
28 KT NE: 170 SE: 190 SW: 190 NW: 90
34 KT NE: 90 SE: 130 SW: 90 NW:
7.A FIRST CLOSED ISOBAR (PRESSURE / AVERAGE DIAM): 1007 HPA / 600 KM
8.A VERTICAL EXTENSION OF CYCLONE CIRCULATION: SHALLOW
1.B FORECASTS:
12H: 2019/03/20 00 UTC: 18.9 S / 83.7 E, VENT MAX= 030 KT, REMNANT LOW
24H: 2019/03/20 12 UTC: 19.3 S / 82.4 E, VENT MAX= 030 KT, REMNANT LOW
36H: 2019/03/21 00 UTC: 19.5 S / 81.0 E, VENT MAX= 030 KT, REMNANT LOW
48H: 2019/03/21 12 UTC: 19.8 S / 79.6 E, VENT MAX= 030 KT, REMNANT LOW
60H: 2019/03/22 00 UTC: 20.2 S / 77.6 E, VENT MAX= 025 KT, FILLING UP
2.B LONGER-RANGE OUTLOOK:
NIL
2.C ADDITIONAL INFORMATION:
SAVANNAH CLOUD PATTERN DID NOT EVOLVE TODAY WITH NO CONVECTIVE
ACTIVITY ON THE TC CORE. A CONVECTIVE BURST JUST OCCURRED BEFORE 12Z IN
THE SOUTHEASTERN QUADRANT. GIVEN THIS SHEARED PATTERN, INTENSITY WAS
DECREASED TO 35KT.
WITH THE WEAKENING OF SAVANNAH, THE STEERING FLOW IS RAPIDLY COMING
DOWN IN THE LOW-LEVELS WHERE THE STRENGTHENING SUBTROPICAL RIDGE IN
THE SOUTH SHOULD CONTINUE TO STEER A GENERALLY WESTSOUTHWESTWARDS
TRACK OVER THE NEXT COUPLE OF DAYS. THE MODEL DISPERSION IS LOW.
OVER THE NEXT DAYS, THIS WEST SOUTH WESTERLY CONSTRAINT DOES NOT
WEAKEN, PREVENTING CONVECTIVE ACTIVITY FROM A SIGNIFICANT COMING
BACK. THE CURRENT WEAKENING IS THUS EXPECTED TO GO ON OVER THE NEXT
DAYS AND SYSTEM SHOULD BECOME A REMNANT LOW BY THURSDAY.
THIS IS THE LAST WARNING ON THIS SYSTEM.

MFR 18Z開始發報，判定為“強烈熱帶氣旋”強度進入責任區。

WTIO31 FMEE 171835
CMRS / CENTRE DES CYCLONES TROPICAUX DE LA REUNION
BULLETIN D'ANALYSE ET DE PREVISION CYCLONIQUE (SUD-OUEST OCEAN INDIEN)
0.A NUMERO DU BULLETIN : 1/12/20182019
1.A CYCLONE TROPICAL INTENSE 12 (SAVANNAH)
2.A POSITION A 1800 UTC LE 17/03/2019 :
DANS UN RAYON DE 20 MN AUTOUR DU POINT 16.5 S / 90.1 E
(SEIZE DEGRES CINQ SUD ET QUATRE-VINGT-DIX DEGRES UN EST)
DEPLACEMENT: OUEST 4 KT
3.A ANALYSE DE DVORAK: 5.0/5.5/W 0.5/6 H
4.A PRESSION AU CENTRE: 962 HPA
5.A VENT MAX (MOYEN/10 MN): 90 KT
RAYON DES VENTS MAXIMAUX (RVM): 28 KM
6.A EXTENSION DES VENTS PAR QUADRANTS (KM):
28 KT NE: 170 SE: 170 SO: 220 NO: 130
34 KT NE: 110 SE: 110 SO: 110 NO: 70
48 KT NE: 60 SE: 60 SO: 60 NO: 50
64 KT NE: 40 SE: 40 SO: 40 NO: 40
7.A COTE/DIAM PREMIERE ISOBARE FERMEE: 1008 HPA / 700 KM
8.A EXTENSION VERTICALE DE LA CIRCULATION CYCLONIQUE: PROFONDE
1.B PREVISIONS:
12H: 18/03/2019 06 UTC: 16.9 S / 89.0 E, VENT MAX= 085 KT, CYCLONE TROPICAL
24H: 18/03/2019 18 UTC: 17.4 S / 87.7 E, VENT MAX= 075 KT, CYCLONE TROPICAL
36H: 19/03/2019 06 UTC: 17.7 S / 86.3 E, VENT MAX= 060 KT, FORTE TEMPETE
TROPICALE
48H: 19/03/2019 18 UTC: 18.1 S / 85.3 E, VENT MAX= 050 KT, FORTE TEMPETE
TROPICALE
60H: 20/03/2019 06 UTC: 18.7 S / 84.1 E, VENT MAX= 040 KT, TEMPETE TROPICALE
MODEREE
72H: 20/03/2019 18 UTC: 19.1 S / 83.1 E, VENT MAX= 035 KT, TEMPETE TROPICALE
MODEREE
2.B TENDANCE ULTERIEURE:
96H: 21/03/2019 18 UTC: 19.6 S / 80.7 E, VENT MAX= 030 KT, DEPRESSION RESIDUELLE
120H: 22/03/2019 18 UTC: 19.9 S / 78.5 E, VENT MAX= 030 KT, DEPRESSION RESIDUELLE
2.C COMMENTAIRES:
T=5.0+ CI=5.5
LE CYCLONE TROPICAL INTENSE SAVANNAH ETAIT JUSQU'ALORS SUIVI PAR LE
CENTRE DE PERTH (BULLETINS IDW27600). A PARTIR DE CE DIMANCHE 17 MARS A
18UTC, LE CMRS DE LA REUNION REPREND LE SUIVI DU SYSTEME SUITE A SON
PASSAGE DU 90°E.
AU COURS DES DERNIERES 6 HEURES, LA CONFIGURATION EN CDO
PRECEDEMMENT ANALYSEE PAR LE CENTRE DE PERTH S'EST MAINTENUE AVEC
UNE CONVECTION QUI RESTE ENCORE BIEN FROIDE. LES IMAGES MICRO-ONDES DE
1246UTC LAISSENT SUPPOSER UNE INTRUSION D'AIR SEC QUI LIMITE UN PEU
L'INTENSITE DU CYCLONE. CEPENDANT, AU COURS DES DERNIERES HEURES, LE
CENTRE DU SYSTEME SE LOCALISE DE PLUS EN PLUS EN LIMITE OUEST DE LA
CONVECTION, POUVANT LAISSER SUPPOSER UNE INFLUENCE GRANDISSANTE DU
CISAILLEMENT DE VENT ENCORE EN LIMITE SUD.
SOUS L'INFLUENCE D'UNE DORSALE DE MOYENNE ALTITUDE AU SUD DU SYSTEME
QUI SE PROLONGE A L'EST, LA TRAJECTOIRE DE SAVANNAH VA PRENDRE UNE
ORIENTATION OUEST-SUD-OUEST. LES DIFFERENTS MODELES SONT EN BON
ACCORD SUR LA DIRECTION OUEST-SUD-OUEST QUI VA SE MAINTENIR AU COURS
DES PROCHAINS JOURS. CEPENDANT ILS PRESENTENT UNE FORTE VARIABILITE EN
TERME DE VITESSE. LES DERNIERES GUIDANCES MONTRENT UNE ACCELERATION
QUI EST PRISE EN COURS DANS LES PREVISIONS DU CMRS.
ACTUELLEMENT DANS UNE ZONE DE FAIBLE CISAILLEMENT DE VENT, SAVANNAH
VA PROGRESSIVEMENT ETRE SOUMIS A UN CISAILLEMENT D'OUEST QUI VA
RAPIDEMENT AUGMENTE PAR LE SUD. LE CONTENU ENERGETIQUE DE L'OCEAN NE
PRESENTANT PAS REELLEMENT DE GENE, C'EST L'ENVIRONNEMENT D'ALTITUDE
QUI VA LIMITER L'INTENSITE DU CYCLONE. TOUT D'ABORD PAR UNE DIMINUTION
TIMIDEMENT AU COURS DES PROCHAINES 24HEURES, UN NET AFFAIBLISSEMENT
EN JOURNEE DE MARDI VA SE FAIRE SENTIR. PAR LA SUITE, TOUJOURS SOUS
L'INFLUENCE D'UN FORT CISAILLEMENT AIDE PAR L'INTRUSION D'AIR SEC,
SAVANNAH VA POURSUIVRE SA ROUTE VERS L'OUEST-SUD-OUEST AU STADE DE
TEMPETE TROPICALE MODEREE AVANT DE COMMENCER SON COMBLEMENT A
PARTIR DE JEUDI.

BoM 06Z報已升格澳式C4！
即將進入MFR責任區

SITUATION
At 0600 UTC Severe Tropical Cyclone Savannah was centred within 20 nautical
miles of
latitude sixteen decimal zero south (16.0S)
longitude ninety one decimal one east (91.1E)
Recent movement : west southwest at 6 knots
Maximum winds   : 95 knots
Central pressure: 951 hPa

FORECAST DATA
Date/Time    : Location    : Loc. Accuracy: Max Wind   : Central Pressure
[UTC]        : degrees     :      nm  [km]: knots[km/h]: hPa
+06:  17/1200: 16.1S  90.6E:     030 [060]:  095  [175]:  951
+12:  17/1800: 16.3S  90.1E:     045 [080]:  095  [175]:  951
+18:  18/0000: 16.5S  89.7E:     055 [105]:  095  [175]:  951
+24:  18/0600: 16.8S  89.2E:     070 [130]:  090  [165]:  957
+36:  18/1800: 17.1S  88.0E:     090 [165]:  085  [155]:  961
+48:  19/0600: 17.4S  86.9E:     110 [200]:  070  [130]:  975
+60:  19/1800: 17.6S  85.9E:     130 [235]:  050  [095]:  989
+72:  20/0600: 18.2S  85.2E:     145 [270]:  045  [085]:  991
+96:  21/0600: 18.7S  83.3E:     190 [355]:  040  [075]:  994
+120: 22/0600: 19.0S  80.7E:     280 [515]:  030  [055]: 1002

JTWC評價100節，發展已超乎預期。

SH, 19, 2019031706,   , BEST,   0, 163S,  910E, 100,  948, TY

BoM 15/18Z再升為澳式C3，近中心最大風速達70kts；JTWC則判定為55kts。

IDW27600
TROPICAL CYCLONE TECHNICAL BULLETIN: AUSTRALIA - WESTERN REGION
Issued by PERTH TROPICAL CYCLONE WARNING CENTRE
at: 1834 UTC 15/03/2019
Name: Severe Tropical Cyclone Savannah
Identifier: 17U
Data At: 1800 UTC
Latitude: 14.8S
Longitude: 94.2E
Location Accuracy: within 25 nm [45 km]
Movement Towards: southwest [216 deg]
Speed of Movement: 5 knots [10 km/h]
Maximum 10-Minute Wind: 70 knots [130 km/h]
Maximum 3-Second Wind Gust: 100 knots [185 km/h]
Central Pressure: 976 hPa
Radius of 34-knot winds NE quadrant: 70 nm [130 km]
Radius of 34-knot winds SE quadrant: 90 nm [165 km]
Radius of 34-knot winds SW quadrant: 90 nm [165 km]
Radius of 34-knot winds NW quadrant: 70 nm [130 km]
Radius of 48-knot winds NE quadrant: 30 nm [55 km]
Radius of 48-knot winds SE quadrant: 30 nm [55 km]
Radius of 48-knot winds SW quadrant: 30 nm [55 km]
Radius of 48-knot winds NW quadrant: 30 nm [55 km]
Radius of 64-knot winds:
Radius of Maximum Winds: 15 nm [30 km]
Dvorak Intensity Code: T4.5/4.5/D1.5/24HRS STT:D0.5/06HRS
Pressure of outermost isobar: 1008 hPa
Radius of outermost closed isobar: 130 nm [240 km]
FORECAST DATA
Date/Time    : Location    : Loc. Accuracy: Max Wind   : Central Pressure
[UTC]        : degrees     :      nm  [km]: knots[km/h]: hPa
+06:  16/0000: 15.2S  93.7E:     030 [060]:  075  [140]:  972
+12:  16/0600: 15.4S  93.3E:     045 [080]:  085  [155]:  968
+18:  16/1200: 15.6S  92.8E:     055 [105]:  085  [155]:  963
+24:  16/1800: 15.9S  92.2E:     070 [130]:  085  [155]:  963
+36:  17/0600: 16.1S  91.1E:     090 [165]:  085  [155]:  963
+48:  17/1800: 16.4S  90.1E:     110 [200]:  085  [155]:  963
+60:  18/0600: 16.6S  89.1E:     130 [235]:  085  [155]:  963
+72:  18/1800: 16.9S  88.1E:     145 [270]:  080  [150]:  968
+96:  19/1800: 17.5S  86.6E:     190 [355]:  055  [100]:  987
+120: 20/1800: 17.9S  85.2E:     280 [515]:  045  [085]:  994
REMARKS:
Severe Tropical Cyclone Savannah was located using microwave imagery. Deep
convection continues to consolidate about the centre responding to the low wind
shear environment.

Dvorak analysis: FT/CI=4.5. Intensity of 70 knots [10 min mean wind], ADT agrees
[CI=4.5].

The prevailing environmental influences are favourable for further
intensification: low wind shear; upper level outflow both equatorward and
particularly poleward in response to a mid-latitude trough to the south; and
SSTs around 28C. Further development is possible right through the weekend.
While dry air lurks on the periphery of the circulation, the fact that wind
shear should continue to be low for several days means the circulation could be
pouched in a moist environment and hence maintain intensity for several days.

The forecast intensity exceeds the range of model guidance possibly because of
the small circulation, but an even more intense system can't be ruled out at
this stage. Rapid intensity Index does not indicate RI is likely but this may be
unduly influenced by dry air on the periphery.

Savannah is continuing to move generally towards the southwest due to a mid
level ridge to the east and an upper trough to the south and will continue to
move away from the Cocos [Keeling] Islands.Over the weekend, the system is
forecast to move towards the west southwest as a mid level ridge builds to the
southwest and the upper level trough passes to the south.

Weakening may be rapid next week once the shear increases and dry air is
ingested however gales may persist long on the southern side owing to motion and
synoptic assistance from the ridge.  

Based on the current official forecast track, Savannah is forecast to cross 90E
[into La Reunion's Area of Responsibility] early on Monday 18 March.

Copyright Commonwealth of Australia
==
The next bulletin for this system will be issued by: 16/0130 UTC by Perth TCWC.

BoM 15/00Z升格為澳式C2，近中心最大風速達50kts。預測巔峰強度上望澳式C3。

IDW27600
TROPICAL CYCLONE TECHNICAL BULLETIN: AUSTRALIA - WESTERN REGION
Issued by PERTH TROPICAL CYCLONE WARNING CENTRE
at: 0115 UTC 15/03/2019
Name: Tropical Cyclone Savannah
Identifier: 17U
Data At: 0000 UTC
Latitude: 13.5S
Longitude: 95.2E
Location Accuracy: within 30 nm [55 km]
Movement Towards: south southwest [203 deg]
Speed of Movement: 5 knots [9 km/h]
Maximum 10-Minute Wind: 50 knots [95 km/h]
Maximum 3-Second Wind Gust: 70 knots [130 km/h]
Central Pressure: 990 hPa
Radius of 34-knot winds NE quadrant: 60 nm [110 km]
Radius of 34-knot winds SE quadrant: 90 nm [165 km]
Radius of 34-knot winds SW quadrant: 90 nm [165 km]
Radius of 34-knot winds NW quadrant: 75 nm [140 km]
Radius of 48-knot winds NE quadrant: 20 nm [35 km]
Radius of 48-knot winds SE quadrant: 20 nm [35 km]
Radius of 48-knot winds SW quadrant: 20 nm [35 km]
Radius of 48-knot winds NW quadrant: 20 nm [35 km]
Radius of 64-knot winds:
Radius of Maximum Winds: 15 nm [30 km]
Dvorak Intensity Code: T3.5/3.5/D0.5/24HRS STT:D0.5/06HRS
Pressure of outermost isobar: 1008 hPa
Radius of outermost closed isobar: 150 nm [280 km]
FORECAST DATA
Date/Time    : Location    : Loc. Accuracy: Max Wind   : Central Pressure
[UTC]        : degrees     :      nm  [km]: knots[km/h]: hPa
+06:  15/0600: 14.0S  95.1E:     040 [080]:  050  [095]:  990
+12:  15/1200: 14.5S  94.9E:     055 [100]:  055  [100]:  988
+18:  15/1800: 14.9S  94.5E:     065 [125]:  055  [100]:  988
+24:  16/0000: 15.1S  94.0E:     080 [145]:  060  [110]:  984
+36:  16/1200: 15.4S  93.0E:     100 [180]:  060  [110]:  984
+48:  17/0000: 15.7S  91.8E:     120 [220]:  065  [120]:  980
+60:  17/1200: 15.8S  90.6E:     140 [255]:  065  [120]:  980
+72:  18/0000: 15.9S  89.7E:     155 [290]:  065  [120]:  980
+96:  19/0000: 16.2S  88.1E:     200 [370]:  050  [095]:  991
+120: 20/0000: 16.6S  86.7E:     290 [535]:  045  [085]:  994
REMARKS:
Tropical Cyclone Savannah was located using EIR imagery and recent microwave
imagery [AMSR2 1903 UTC, SSMI 2027 UTC, TC_SSMIS 2246 UTC].

Deep convection has started to wrap around the centre. Microwave imagery showed
a pin hole eye with deep convection to the north and east of the centre.

Dvorak analysis: Curved band wrap of 0.8 on EIR imagery yielded a DT of 3.5.
Trend is D with PAT of 3.5. FT/CI set to 3.5 with intensity of 50 knots [10 min
mean wind]. CIMMS ADT was 3.5 and NESDIS ADT was 3.7 around 00 UTC. SATCON at
1927 UTC was 48 knots [1 min mean wind].

CIMMS wind shear at 21 UTC was E'ly around 5 to 10 knots. Upper winds showed
moderate outflow equatorward. SSTs are between 28 and 30C.

Savannah is continuing to move generally towards the southwest due to a mid
level ridge to the east and an upper trough to the south and will continue to
move away from the Cocos [Keeling] Islands.Over the weekend, the system is
forecast to move towards the west southwest as a mid level ridge builds to the
southwest and an upper level trough passes to the south. ECMWF has more of a
southwest track with the majority of other guidance favouring a more westerly
track. This is likely due to the influence of the upper level trough.

Savannah is intensifying and with shear expected to remain low, is forecast to
reach category 3 intensity on Sunday or as early as Saturday. There is potential
for dry air to wrap around the periphery over the weekend and into next week.
Shear is also forecast to increase and with cooler SSTs, Savannah is expected to
weaken early next week.


Copyright Commonwealth of Australia
==
The next bulletin for this system will be issued by: 15/0730 UTC by Perth TCWC.

BoM 00Z命名Savannah

IDW27600
TROPICAL CYCLONE TECHNICAL BULLETIN: AUSTRALIA - WESTERN REGION
Issued by PERTH TROPICAL CYCLONE WARNING CENTRE
at: 0130 UTC 14/03/2019
Name: Tropical Cyclone Savannah
Identifier: 17U
Data At: 0000 UTC
Latitude: 11.6S
Longitude: 96.5E
Location Accuracy: within 30 nm [55 km]
Movement Towards: south southwest [206 deg]
Speed of Movement: 7 knots [12 km/h]
Maximum 10-Minute Wind: 40 knots [75 km/h]
Maximum 3-Second Wind Gust: 55 knots [100 km/h]
Central Pressure: 998 hPa
Radius of 34-knot winds NE quadrant: 30 nm [55 km]
Radius of 34-knot winds SE quadrant: 30 nm [55 km]
Radius of 34-knot winds SW quadrant: 45 nm [85 km]
Radius of 34-knot winds NW quadrant: 45 nm [85 km]
Radius of 48-knot winds NE quadrant:   
Radius of 48-knot winds SE quadrant:   
Radius of 48-knot winds SW quadrant:   
Radius of 48-knot winds NW quadrant:   
Radius of 64-knot winds:
Radius of Maximum Winds: 20 nm [35 km]
Dvorak Intensity Code: T3.0/3.0/D0.5/24HRS STT: D0.5/06HRS
Pressure of outermost isobar: 1008 hPa
Radius of outermost closed isobar: 130 nm [240 km]
FORECAST DATA
Date/Time    : Location    : Loc. Accuracy: Max Wind   : Central Pressure
[UTC]        : degrees     :      nm  [km]: knots[km/h]: hPa
+06:  14/0600: 12.3S  96.3E:     040 [080]:  040  [075]:  998
+12:  14/1200: 12.9S  96.3E:     055 [100]:  040  [075]:  998
+18:  14/1800: 13.6S  96.3E:     065 [125]:  045  [085]:  994
+24:  15/0000: 14.1S  96.2E:     080 [145]:  045  [085]:  994
+36:  15/1200: 15.1S  96.0E:     100 [180]:  045  [085]:  994
+48:  16/0000: 15.7S  95.4E:     120 [220]:  050  [095]:  991
+60:  16/1200: 16.2S  94.6E:     140 [255]:  055  [100]:  987
+72:  17/0000: 16.4S  93.6E:     155 [290]:  060  [110]:  984
+96:  18/0000: 16.8S  91.8E:     200 [370]:  060  [110]:  983
+120: 19/0000: 17.2S  90.0E:     290 [535]:  050  [095]:  991
REMARKS:
Tropical Cyclone Savannah was named at 21UTC and was located using EIR and
microwave imagery [SSMIS 13/2257UTC].

Deep convection continues to persist on the western flank. Partial scatterometry
passes around 1430 UTC showed 30 to 40 knot winds to the west of the centre.

Dvorak analysis: Shear pattern, <0.5 degree from strong T gradient yields a DT
of 3.0. Trend is D-, MET/PAT is 3.0. FT/CI set to 3.0 with intensity of 40 knots
[10 minute mean wind].

CIMSS wind shear at 21 UTC was E'ly between 20 and 25 knots, and upper winds
showed moderate outflow equatorward. SSTs are between 28 and 30C.

Savannah is continuing to move generally towards the south-southwest due to a
mid level ridge to the east. Shear is forecast to decrease during Thursday as an
upper trough passes to the south. The system will pass to the west of the Cocos
[Keeling] Islands during Thursday with a period of gales possible. Peak gust
recorded to date was 43 knots at 2135 UTC.

Over the weekend, the system is forecast to move towards the west southwest as a
mid level ridge builds to the southwest and an upper level trough passes to the
south. Savannah is forecast to reach category 2 intensity on Saturday as shear
is forecast to remain low, though this could occur as early as Friday evening.
There is potential for Savannah to reach category 3 intensity on Sunday or
Monday with improved poleward outflow. There is potential for dry air to wrap
around the periphery over the weekend and into next week. It is unclear whether
this will impact the intensity as there is uncertainty surrounding the
likelihood of this dry air being ingested into the system.

Copyright Commonwealth of Australia
==
The next bulletin for this system will be issued by: 14/0730 UTC by Perth TCWC.