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  五級強烈熱帶氣旋  
編號：21 F ( 18 P )
名稱：Donna

  基本資料  
擾動編號日期：2017 年 04 月 30 日 08 時
JTWC升格日期:2017 年 05 月 03 日 02 時
命名日期　　：2017 年 05 月 03 日 15 時
撤編日期　　：2017 年 05 月 11 日 13 時
登陸地點　　：暫無

  巔峰時期資料  
近中心最強風速
斐濟氣象局 (FMS) :  110 kt
聯合颱風警報中心(JTWC): 120 kt ( Cat.4 )
海平面最低氣壓    ：935 百帕

  過去路徑圖  

  擾動編號資料  
99P.INVEST.15kts.NAmb.11.2S 162.9E


以上資料來自：FMS、JTWC、颱風論壇整理製作

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JTWC:LOW

(1) AN AREA OF CONVECTION (INVEST 99P) HAS PERSISTED NEAR
11.8S 165.4E, APPROXIMATELY 785 NM WEST-NORTHWEST OF NADI, FIJI.
ANIMATED MULTISPECTRAL SATELLITE IMAGERY SHOWS AN ELONGATED
CIRCULATION WITH FLARING CONVECTION LOCATED OVER THE DISTURBANCE. A
302158Z AMSU-B METOP-B 89GHZ MICROWAVE IMAGE SHOWS FRAGMENTED
CONVECTION ASSOCIATED WITH A VERY ELONGATED LOW LEVEL CIRCULATION.
THE DISTURBANCE IS LOCATED IN A MARGINAL ENVIRONMENT DUE TO MODERATE
VERTICAL WIND SHEAR (15-20 KNOTS), BUT IS OFFSET BY GOOD UPPER LEVEL
OUTFLOW AND WARM SEA SURFACE TEMPERATURES (28-29 CELSIUS). GLOBAL
MODELS ARE IN AGREEMENT THAT THE DISTURBANCE WILL TRACK TO THE EAST
OVER THE NEXT FEW DAYS, BUT BECOME SPLIT AS TO THE TRACK AND
INTENSITY IN THE LATER TAUS. MAXIMUM SUSTAINED SURFACE WINDS ARE
ESTIMATED AT 10 TO 15 KNOTS. MINIMUM SEA LEVEL PRESSURE IS ESTIMATED
TO BE NEAR 1008 MB. THE POTENTIAL FOR THE DEVELOPMENT OF A
SIGNIFICANT TROPICAL CYCLONE WITHIN THE NEXT 24 HOURS IS LOW.
      (2) NO OTHER SUSPECT AREAS

s6815711

05Z評級提升至Medium

(1) THE AREA OF CONVECTION (INVEST 99P) PREVIOUSLY LOCATED
NEAR 11.8S 165.4E, IS NOW LOCATED NEAR 11.9S 167.6E, APPROXIMATELY
350 NM NORTH OF PORT VILA , VANUATU. ANIMATED MULTI-SPECTRAL
SATELLITE IMAGERY AND A 010256Z GMI 37GHZ MICROWAVE PASS SHOWED  
PERSISTENT DEEP FLARING CONVECTION AND FRAGMENTED BANDING ASSOCIATED
WITH AN ELONGATED LOW LEVEL CIRCULATION (LLC), WHICH WAS
EXTRAPOLATED FROM A 302159 25KM METOP-B DESCENDING ASCAT PASS, AND
ALSO SUGGESTED IN AN 850MB VORTICITY PRODUCT. PERIPHERAL WINDS ON
THE EQUATORWARD SIDE OF THE NORTHWEST TO SOUTHEAST ORIENTED LLC ARE
15-30 KNOTS AND 15-20 KNOTS ON THE POLEWARD SIDE. UPPER-LEVEL
ANALYSIS REVEALS A MARGINALLY FAVORABLE ENVIRONMENT WITH MODEST
RADIAL OUTFLOW ASSOCIATED WITH A POINT SOURCE OVERHEAD AND LIGHT TO
MODERATE (10-20 KNOTS) VERTICAL WIND SHEAR, IN ADDITION TO WARM SEA
SURFACE TEMPERATURES (28-29 CELSIUS). GLOBAL MODELS ARE IN AGREEMENT
THAT THE DISTURBANCE WILL TRACK EAST-SOUTHEASTWARD OVER THE NEXT
COUPLE OF DAYS BEFORE HOOKING BACK WESTWARD. MAXIMUM SUSTAINED
SURFACE WINDS ARE ESTIMATED AT 10 TO 15 KNOTS. MINIMUM SEA LEVEL
PRESSURE IS ESTIMATED TO BE NEAR 1008 MB. BASED ON DATA ANALYZED AND
IMPROVED STRUCTURE OF THIS DISTURBANCE, THE POTENTIAL FOR THE
DEVELOPMENT OF A SIGNIFICANT TROPICAL CYCLONE WITHIN THE NEXT 24
HOURS IS UPGRADED TO MEDIUM.

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TCFA

WTPS21 PGTW 012100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/TROPICAL CYCLONE FORMATION ALERT//
RMKS/
1. FORMATION OF A SIGNIFICANT TROPICAL CYCLONE IS POSSIBLE WITHIN
120 NM EITHER SIDE OF A LINE FROM 12.5S 169.9E TO 14.6S 173.6E
WITHIN THE NEXT 12 TO 24 HOURS. AVAILABLE DATA DOES NOT JUSTIFY
ISSUANCE OF NUMBERED TROPICAL CYCLONE WARNINGS AT THIS TIME.
WINDS IN THE AREA ARE ESTIMATED TO BE 25 TO 30 KNOTS. METSAT
IMAGERY AT 011800Z INDICATES THAT A CIRCULATION CENTER IS LOCATED
NEAR 12.7S 170.2E. THE SYSTEM IS MOVING EAST-SOUTHEASTWARD AT 06
KNOTS.
2. REMARKS: ANIMATED INFRARED/MULTI-SPECTRAL SATELLITE IMAGERY AND A
011909Z SSMIS 91 GHZ MICROWAVE PASS SHOWED DEEP, PERSISTENT AND
FLARING CONVECTION WITH FRAGMENTED BANDING WRAPPING INTO A
LOW-LEVEL CIRCULATION CENTER (LLCC). A 011032Z 25KM (METOP-B)
PARTIAL ASCAT PASS REVEALS PRIMARILY 20-25 KNOT WINDS WITH A FEW
30 KNOT WIND BARBS AROUND THE EASTERN PERIPHERY OF AN EXTRAPOLATED
LLCC. UPPER-LEVEL ANALYSIS INDICATES A FAVORABLE ENVIRONMENT WITH A
MODERATE POLEWARD OUTFLOW CHANNEL ASSOCIATED WITH A POINT
SOURCE OVERHEAD AND LIGHT TO MODERATE (10-15 KNOTS) VERTICAL WIND
SHEAR, IN ADDITION TO WARM SEA SURFACE TEMPERATURES (28-29 CELSIUS).
GLOBAL MODELS ARE IN AGREEMENT THAT THE DISTURBANCE WILL TRACK EAST-
SOUTHEASTWARD OVER THE NEXT COUPLE OF DAYS BEFORE HOOKING BACK
TOWARD A SOUTHWESTWARD DIRECTION. MAXIMUM SUSTAINED SURFACE WINDS
ARE ESTIMATED AT 25 TO 30 KNOTS. MINIMUM SEA LEVEL PRESSURE IS
ESTIMATED TO BE NEAR 1000 MB. THE POTENTIAL FOR THE DEVELOPMENT OF A
SIGNIFICANT TROPICAL CYCLONE WITHIN THE NEXT 24 HOURS IS HIGH.
3. THIS ALERT WILL BE REISSUED, UPGRADED TO WARNING OR CANCELLED BY
022100Z.
//
NNNN

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Tropical Disturbance Summary For area Equator to 25S, 160E to 120W
ISSUED FROM RSMC NADI May 020930 UTC.

TROPICAL DISTURBANCE TD21F CENTER [1004HPA] WAS ANALYSED NEAR 12.1S
171.2E AT 020900UTC MOVING EASTWARDS AT ABOUT 05 KNOTS. POSITION POOR
BASED ON HIMAWARI-8 EIR IMAGERY WITH ANIMATIONS AND PERIPHERAL
SURFACE OBSERVATIONS.

ORGANISATION IS POOR WITH DEEP CONVECTION DISPLACED TO THE EAST OF
THE SUPPOSED LLCC. CYCLONIC CIRCULATION EXTENDS UPTO 500HPA. SYSTEM
LIES JUST SOUTH OF AN UPPER RIDGE IN A MODERATE SHEARED ENVIRONMENT.
SST AROUND 30 DEGREES CELSIUS.

GLOBAL MODELS SLOWLY MOVE TD21F WEST-SOUTHWESTWARDS WITH FURTHER
INTENSIFICATION.

POTENTIAL FOR THIS SYSTEM TO DEVELOP INTO A TROPICAL CYCLONE IN THE
NEXT 24 TO 48 HOURS IS LOW.

*********************************************************************
***************

NO OTHER SIGNIFICANT TROPICAL DISTURBANCE ANALYSED OR FORECAST IN THE
AREA.

FMS: LOW

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系統的對流頗深厚，主要集中在中心密集雲區的東面，雲頂溫度受日際變化影響稍有回升。