JTWC 06Z強度升一級颶風，也是印尼名首個C1，MFR 強度升強烈熱帶風暴，逐漸南下轉化。

WTIO31 FMEE 301825
CMRS / CENTRE DES CYCLONES TROPICAUX DE LA REUNION
BULLETIN D'ANALYSE ET DE PREVISION CYCLONIQUE (SUD-OUEST OCEAN INDIEN)
0.A NUMERO DU BULLETIN : 9/9/20172018
1.A FORTE TEMPETE TROPICALE 9 (FLAMBOYAN)
2.A POSITION A 1800 UTC LE 30/04/2018 :
DANS UN RAYON DE 25 MN AUTOUR DU POINT 16.4 S / 84.4 E
(SEIZE DEGRES QUATRE SUD ET QUATRE-VINGT QUATRE DEGRES QUATRE EST)
DEPLACEMENT: SUD 7 KT
3.A ANALYSE DE DVORAK : 3.5/4.0/W 0.5/6 H
4.A PRESSION AU CENTRE : 985 HPA
5.A VENT MAX (MOYEN/10 MN): 60 KT
RAYON DES VENTS MAXIMAUX (RVM) :46 KM
6.A EXTENSION DES VENTS PAR QUADRANTS (KM) :
28 KT NE: 240 SE: 430 SO: 430 NO: 200
34 KT NE: 160 SE: 260 SO: 260 NO: 120
48 KT NE: 70 SE: 90 SO: 90 NO: 70
7.A COTE/DIAM PREMIERE ISOBARE FERMEE: 1009 HPA / 700 KM
8.A EXTENSION VERTICALE DE LA CIRCULATION CYCLONIQUE : PROFONDE
1.B PREVISIONS :
12H: 01/05/2018 06 UTC: 18.2 S / 84.4 E, VENT MAX=055 KT, FORTE TEMPETE TROPICALE
24H: 01/05/2018 18 UTC: 19.9 S / 84.5 E, VENT MAX=050 KT, DEPRESSION POSTTROPICALE

36H: 02/05/2018 06 UTC: 21.1 S / 85.0 E, VENT MAX=045 KT, DEPRESSION POSTTROPICALE

48H: 02/05/2018 18 UTC: 23.0 S / 86.6 E, VENT MAX=040 KT, DEPRESSION POSTTROPICALE

60H: 03/05/2018 06 UTC: 25.5 S / 88.9 E, VENT MAX=035 KT, DEPRESSION POSTTROPICALE

72H: 03/05/2018 18 UTC: 27.9 S / 92.6 E, VENT MAX=040 KT, DEPRESSION
EXTRATROPICALE
2.B TENDANCE ULTERIEURE:
2.C COMMENTAIRES :
T=3.5 CI=4.0-
APRES UNE AMELIORATION EN DEBUT DE JOURNEE, LA CONFIGURATION
NUAGEUSE DE FLAMBOYAN SUGGERE DE PLUS EN PLUS, UN RENFORCEMENT DE
LA CONTRAINTE DE SECTEUR NORD-OUEST EN ALTITUDE (20 KT ANALYSE PAR LE
CIMSS A 15Z). CELA SEMBLE CONFIRME PAR LES DERNIERES MICRO-ONDES (SSMIS
1306Z ET AMSU 1543Z) AVEC UN POSSIBLE DECALAGE ENTRE LES CIRCULATIONS
D'ALTITUDE ET DE SURFACE. LA PHASE D'AFFAIBLISSEMENT A DONC TRES
PROBABLEMENT COMMENCE. CEPENDANT AU VU DES DONNEES ASCAT
PARTIELLES DE 1543Z ET DE LA PASSE SMAP DE 1220Z, LES VENTS MAXIMAUX SONT
MAINTENUES PAR INERTIE.
FLAMBOYAN NE BENEFICIE PLUS MAINTENANT DE CONDITIONS FAVORABLES A UN
CREUSEMENT TROPICAL AVEC LE RENFORCEMENT PROGRESSIF DU CISAILLEMENT
VERTICAL. DE PLUS, LE POTENTIEL ENERGETIQUE DEVIENT INSUFFISANT DEMAIN
SOIR AU SUD DE 18S. NEANMOINS, DEMAIN ET JEUDI, SUITE A L'INTERACTION AVEC
DES ANOMALIES D'ALTITUDES DES RENFORCEMENTS TEMPORAIRES SONT
POSSIBLES EN LIEN AVEC DES PROCESSUS BAROCLINES.
FLAMBOYAN CONTINUE DE CONTOURNER LA CELLULE DE HAUTS GEOPOTENTIELS
DE BASSE A MOYENNE TROPO PRESENTE A L'EST AVEC UN RECOURBEMENT
GRADUEL VERS LE SUD-EST ENVISAGE SUR LA PERIODE DE PREVISION. A PARTIR
DE MERCREDI, IL DEVRAIT ACCELERER A L'AVANT D'UN PUISSANT THALWEG DES
MOYENNES LATITUDES.

法國氣象局定在9.9S 90.1E，但JTWC定在10.2S 89.6E。

前面強度沿用BMKG，預報上看強烈熱帶風暴。Flamboyan是西南印度洋史上首個由印尼命名的中等熱帶風暴。

印尼命名Flamboyan，為本風季第三個印尼命名、歷史上第六個。即將離開責任區。

EGC:2:1:24:09S091E900:11:00
THIS WARNING IS PROVIDED BY TROPICAL CYCLONE WARNING CENTRE JAKARTA
AND ISSUED FOR THE CIRCULAR AREA OF METAREA XIXIXIPORBY JMA

INDONESIAN AGENCY FOR METEOROLOGY CLIMATOLOGY AND GEOPHYSICS
Tropical Cyclone Warning Centre (TCWC) Jakarta

SECURITE

            OCEAN GALE AND STORM WARNING

OCEAN GALE AND STORM WARNING FOR AREA 0 - 10 S, 90 - 125 E
Issued by JAKARTA TROPICAL CYCLONE WARNING CENTRE
At: 14:08 UTC 28 April 2018

SITUATION
At 12:00 UTC Tropical Cyclone FLAMBOYAN 996 hPa at 8,6 S 90,5 E moving west northwest at 5 knots.


FORECAST
Clockwise winds reaching 35 knots expected to increase to 45 knots in the next 24 hours.
High seas may exceed Rough to Very Rough scale and rising swell.

00:00 UTC 29 April:  Within 60 nautical miles of 9,9 S 88,3 E
                        Central pressure 991 hPa.
                        Wind speed reaching 40 knots near centre.
12:00 UTC 29 April: Within 90 nautical miles of 11,2 S 86,3 E
                        Central pressure 990 hPa.
                        Wind speed reaching 45 knots near centre.

REMARKS
Ships please transmit 3-hourly weather reports.
Next warning will be issued by 19:00 UTC 28 April 2018.


Tropical Cyclone Warning Centre JAKARTA

BoM 目前認為中等機會會發展...

Tropical Cyclone Outlook for the Western Region
Issued at 2:00 pm WST on Saturday 28 April 2018
for the period until midnight WST Tuesday 1 May 2018.

Existing Cyclones in the Western Region:
Nil.

Potential Cyclones:

A tropical low is situated to the north of the region, near 08.3S 093.2E. The low is tracking southwest and may move into the far northwest of the region later tonight or during early Sunday morning. The system is slowly intensifying and there is a risk that the system will reach tropical cyclone intensity while in the Western Region. On Sunday, the system will continue to track further west or southwest and will move outside the region.


Likelihood of a tropical cyclone in the Western Region on:
Sunday:Moderate
Monday:Very Low
Tuesday:Very Low

BMKG 升格熱帶低壓，預計會在90E附近命名，或是進入MFR責任區，由MFR命名。

JTWC 06Z率先格熱帶氣旋，編號21S，發展快速，巔峰上望一級颶風。

JTWC 00Z發佈"TCFA"，分析到T2.0。

TXXS26 KNES 280016
TCSSIO

A.  TROPICAL DISTURBANCE (98S)

B.  27/2330Z

C.  7.6S

D.  94.4E

E.  FIVE/HIMAWARI-8

F.  T2.0/2.0/D1.0/24HRS

G.  IR/EIR/SWIR

H.  REMARKS...THIS INTENSITY ESTIMATE WAS DERIVED USING 4 KM IR
DATA. 3.5/10 BANDING RESULTS IN A DT OF 2.0. MET IS 1.5. PT IS 2.0. FT
IS BASED ON DT.

I.  ADDL POSITIONS

    NIL
...ZHU

JTWC 12Z評級Low

(1) AN AREA OF CONVECTION (INVEST 98S) HAS PERSISTED NEAR 7.5S
97.0E, APPROXIMATELY 276 NM NORTH OF COCOS ISLAND, AUSTRALIA.
ANIMATED ENHANCED INFRARED SATELLITE IMAGERY SHOWS A CONSOLIDATING
BROAD LOW LEVEL CIRCULATION AND FLARING CONVECTION. A 270839Z SSMI
85GHZ MICROWAVE IMAGE REVEALS FORMATIVE LOW LEVEL BANDING AND
ORGANIZING DEEP CONVECTION. ENVIRONMENTAL ANALYSIS INDICATES THAT
INVEST 98S IS LOCATED IN AN AREA OF LOW (10-15 KNOT) VERTICAL WIND
SHEAR AND BURGEONING DIVERGENCE ALOFT. WARM (28-29C) SEA SURFACE
TEMPERATURES ARE CONDUCIVE TO DEVELOPMENT. GLOBAL MODELS PREDICT
THAT INVEST 98S WILL DEVELOP WITHIN THE NEXT SEVERAL DAYS AS IT
TRACKS TOWARDS THE SOUTHWEST, BUT VARY ON THE TIMEFRAME OF
DEVELOPMENT. MAXIMUM SUSTAINED SURFACE WINDS ARE ESTIMATED AT 20 TO
25 KNOTS. MINIMUM SEA LEVEL PRESSURE IS ESTIMATED TO BE NEAR 1004
MB. THE POTENTIAL FOR THE DEVELOPMENT OF A SIGNIFICANT TROPICAL
CYCLONE WITHIN THE NEXT 24 HOURS IS LOW.