罗德里格斯岛以东强热带风暴第13号“伊沃娜”(23U/24S.Ivone) - 西南移动

yhh

WTXS31 PGTW 100900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/TROPICAL CYCLONE 24S (IVONE) WARNING NR 005//
RMKS/
1. TROPICAL CYCLONE 24S (IVONE) WARNING NR 005   
   02 ACTIVE TROPICAL CYCLONES IN SOUTHIO
   MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE
   WIND RADII VALID OVER OPEN WATER ONLY
    ---
   WARNING POSITION:
   100600Z --- NEAR 19.2S 82.2E
     MOVEMENT PAST SIX HOURS - 210 DEGREES AT 10 KTS
     POSITION ACCURATE TO WITHIN 030 NM
     POSITION BASED ON CENTER LOCATED BY SATELLITE
   PRESENT WIND DISTRIBUTION:
   MAX SUSTAINED WINDS - 045 KT, GUSTS 055 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   RADIUS OF 034 KT WINDS - 200 NM NORTHEAST QUADRANT
                            230 NM SOUTHEAST QUADRANT
                            200 NM SOUTHWEST QUADRANT
                            075 NM NORTHWEST QUADRANT
   REPEAT POSIT: 19.2S 82.2E
    ---
   FORECASTS:
   12 HRS, VALID AT:
   101800Z --- 20.0S 80.8E
   MAX SUSTAINED WINDS - 045 KT, GUSTS 055 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   RADIUS OF 034 KT WINDS - 060 NM NORTHEAST QUADRANT
                            260 NM SOUTHEAST QUADRANT
                            210 NM SOUTHWEST QUADRANT
                            090 NM NORTHWEST QUADRANT
   VECTOR TO 24 HR POSIT: 270 DEG/ 09 KTS
    ---
   24 HRS, VALID AT:
   110600Z --- 20.0S 78.9E
   MAX SUSTAINED WINDS - 045 KT, GUSTS 055 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   RADIUS OF 034 KT WINDS - 020 NM NORTHEAST QUADRANT
                            220 NM SOUTHEAST QUADRANT
                            200 NM SOUTHWEST QUADRANT
                            070 NM NORTHWEST QUADRANT
   VECTOR TO 36 HR POSIT: 275 DEG/ 12 KTS
    ---
   36 HRS, VALID AT:
   111800Z --- 19.7S 76.3E
   MAX SUSTAINED WINDS - 040 KT, GUSTS 050 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   RADIUS OF 034 KT WINDS - 020 NM NORTHEAST QUADRANT
                            190 NM SOUTHEAST QUADRANT
                            170 NM SOUTHWEST QUADRANT
                            040 NM NORTHWEST QUADRANT
   VECTOR TO 48 HR POSIT: 265 DEG/ 14 KTS
    ---
   EXTENDED OUTLOOK:
   48 HRS, VALID AT:
   120600Z --- 19.8S 73.3E
   MAX SUSTAINED WINDS - 040 KT, GUSTS 050 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   RADIUS OF 034 KT WINDS - 050 NM NORTHEAST QUADRANT
                            190 NM SOUTHEAST QUADRANT
                            120 NM SOUTHWEST QUADRANT
                            000 NM NORTHWEST QUADRANT
   VECTOR TO 72 HR POSIT: 245 DEG/ 12 KTS
    ---
   72 HRS, VALID AT:
   130600Z --- 21.8S 68.6E
   MAX SUSTAINED WINDS - 035 KT, GUSTS 045 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   DISSIPATING AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER
   RADIUS OF 034 KT WINDS - 050 NM NORTHEAST QUADRANT
                            120 NM SOUTHEAST QUADRANT
                            060 NM SOUTHWEST QUADRANT
                            010 NM NORTHWEST QUADRANT
   VECTOR TO 96 HR POSIT: 210 DEG/ 12 KTS
    ---
   LONG RANGE OUTLOOK:
    ---
   96 HRS, VALID AT:
   140600Z --- 25.8S 65.9E
   MAX SUSTAINED WINDS - 030 KT, GUSTS 040 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   DISSIPATED AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER
    ---
REMARKS:
100900Z POSITION NEAR 19.4S 81.9E.
10MAR25. TROPICAL CYCLONE 24S (IVONE), LOCATED APPROXIMATELY 1407
NM EAST OF PORT LOUIS, MAURITIUS, HAS TRACKED SOUTH-SOUTHWESTWARD
AT 10 KNOTS OVER THE PAST SIX HOURS. MINIMUM CENTRAL PRESSURE AT
100600Z IS 993 MB. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 100600Z IS
30 FEET. NEXT WARNINGS AT 102100Z AND 110900Z. REFER TO TROPICAL
CYCLONE 25S (JUDE) FINAL WARNING (WTXS32 PGTW).//
NNNN

1. WDXS31 PGTW 100900
   
2. MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
   
3. SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 24S (IVONE)
   
4. WARNING NR 005//
   
5. RMKS/
   
6. 1. FOR METEOROLOGISTS.
   
7. 2. 6 HOUR SUMMARY AND ANALYSIS.
   
8. 
   
9. SUMMARY:
   
10.    INITIAL POSITION: 19.2S 82.2E
    
11.    INITIAL INTENSITY: 45 KTS
    
12.    GEOGRAPHIC REFERENCE: 1407 NM EAST OF PORT LOUIS, MAURITIUS
    
13.    MOVEMENT PAST 6 HOURS: SOUTH-SOUTHWESTWARD AT 10 KTS
    
14.    SIGNIFICANT WAVE HEIGHT: 30 FEET
    
15. 
    
16. SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
    
17. ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS AN EXPOSED,
    
18. BROAD LOW-LEVEL CIRCULATION CENTER (LLCC), WITH A SYMMETRIC REGION OF
    
19. DEEP CONVECTION SHEARED OVER THE SOUTHERN SEMICIRCLE. DESPITE MODERATE
    
20. TO STRONG NORTHWESTERLY VERTICAL WIND SHEAR (VWS), THE SYSTEM HAS
    
21. MAINTAINED A ROBUST POLEWARD OUTFLOW CHANNEL WITH SHORT-LIVED PULSES
    
22. OF WESTWARD AND NORTHWARD OUTFLOW. UNFORTUNATELY, EXTENSIVE DRY AIR
    
23. OVER THE WESTERN AND NORTHERN SEMICIRCLES HAS CONTINUED TO HINDER
    
24. SIGNIFICANT DEVELOPMENT. A 100417Z ASCAT-C IMAGE REVEALS AN ELONGATED
    
25. CENTER, WITH EXTENSIVE GALE-FORCE WINDS (35-45 KNOTS) OVER THE
    
26. SOUTHERN SEMICIRCLE. THE INITIAL POSITION IS PLACED WITH MEDIUM
    
27. CONFIDENCE BASED ON EXTRAPOLATION FROM THE ASCAT-C IMAGE. THE INITIAL
    
28. INTENSITY OF 45 KTS IS ASSESSED WITH HIGH CONFIDENCE BASED ON THE
    
29. ASCAT-C IMAGE AND AN EARLIER SMOS IMAGE. THE 34-KNOT WIND RADII HAVE
    
30. BEEN ADJUSTED TO REFLECT THE ASCAT-C DATA.
    
31. 
    
32. INITIAL WIND RADII BASIS: SCATTEROMETER DATA
    
33. 
    
34. CURRENT STEERING MECHANISM: DEEP-LAYER SUBTROPICAL RIDGE (STR)
    
35. POSITIONED TO THE SOUTHEAST AND SOUTH
    
36. 
    
37. AGENCY DVORAK AND AUTOMATED FIXES:
    
38.    PGTW: T3.0 - 45 KTS
    
39.    KNES: T3.5 - 55 KTS
    
40.    DEMS: T3.0 - 45 KTS
    
41.    FIMP: T3.0 - 45 KTS
    
42.    CIMSS SATCON: 43 KTS AT 100129Z
    
43.    CIMSS ADT: 49 KTS AT 100600Z
    
44.    CIMSS AIDT: 40 KTS AT 100500Z
    
45.    CIMSS D-PRINT: 49 KTS AT 100600Z
    
46. 
    
47. FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINAL
    
48.    VWS: 20-25 KTS
    
49.    SST: 27-28 CELSIUS
    
50.    OUTFLOW: STRONG POLEWARD
    
51.    OTHER FACTORS: DRY AIR ENTRAINMENT
    
52. 
    
53. ANALYSIS CONFIDENCE:
    
54.    INITIAL POSITION: MEDIUM
    
55.    INITIAL INTENSITY: HIGH
    
56.    INITIAL WIND RADII: MEDIUM
    
57. 
    
58. 3. FORECAST REASONING.
    
59. 
    
60. SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO
    
61. THE FORECAST FROM THE PREVIOUS WARNING.
    
62. 
    
63. FORECAST DISCUSSION: WITHIN THE NEXT 24 HOURS, TC 24S WILL TURN
    
64. SOUTHWESTWARD THEN WESTWARD AS IT TRACKS ALONG THE BUILDING STR TO
    
65. THE SOUTH. AFTER TAU 72, THE SYSTEM WILL RECURVE SOUTHWESTWARD
    
66. AROUND THE NORTHWEST PERIPHERY OF THE STR. TC 24S IS EXPECTED TO
    
67. WEAKEN STEADILY THROUGH THE FORECAST PERIOD AS ENVIRONMENTAL
    
68. CONDITIONS DETERIORATE. OVER THE NEXT 24 HOURS, THE ROBUST POLEWARD
    
69. CHANNEL INTO THE SUBTROPICAL JET WILL CEASE, WITH THE STJ WEAKENING
    
70. AND SHIFTING EASTWARD. THE SYSTEM WILL ALSO TRACK UNDER THE LEADING
    
71. EDGE OF AN UPPER-LEVEL TROUGH, WITH INCREASING VWS (30-35 KNOTS)
    
72. AND A VERY DRY ENVIRONMENT. CONSEQUENTLY, THE SYSTEM IS FORECAST TO
    
73. DISSIPATE BY TAU 96 AS IT BEGINS TO RECURVE.
    
74. 
    
75. MODEL DISCUSSION: NUMERICAL MODEL TRACK GUIDANCE IS IN FAIR
    
76. AGREEMENT, WITH A 160NM CROSS-TRACK SPREAD AT TAU 72 AND A 250NM
    
77. CROSS-TRACK SPREAD AT TAU 96. THE 100000Z GEFS AND EPS RUNS SHOW A
    
78. SIMILAR TRACK SPREAD, WITH THE BULK OF SOLUTIONS SUPPORTING THE
    
79. DISSIPATION SCENARIO. RELIABLE INTENSITY GUIDANCE ALSO SUPPORTS THE
    
80. STEADY WEAKENING TREND AND DISSIPATION SCENARIO.
    
81. 
    
82. FORECAST CONFIDENCE:
    
83.    TRACK 0 - 72 HR: MEDIUM
    
84.    TRACK 72-120 HR: MEDIUM
    
85.    INTENSITY 0 - 72 HR: MEDIUM
    
86.    INTENSITY 72-120 HR: MEDIUM//
    
87. NNNN

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pocketbox

全球热带气旋监测公报
预报：宋佳凝  签发：钱奇峰  2025 年 03 月 10 日 18 时
“伊沃娜”向西南方向移动

时       间：10日14时（北京时）

海       域：南印度洋

命       名：“伊沃娜”，IVONE

中心位置：南纬19.5度、东经82.3度

强度等级：热带风暴

最大风力：8级（20米/秒，相当于我国的热带风暴级）

中心气压：989百帕

参考位置：毛里求斯路易港偏东方向约2590公里的洋面上

变化过程：过去24小时，“伊沃娜”由9级减弱到8级

预报结论：“伊沃娜”将以每小时10-15公里的速度向西南方向移动，强度变化不大。


图3 卫星红外监测图像（北京时间2025年03月10日14时00分）

ygsj24

WTIO30 FMEE 101334
RSMC / TROPICAL CYCLONE CENTER / LA REUNION
TROPICAL CYCLONE FORECAST WARNING (SOUTH-WEST INDIAN OCEAN)

0.A WARNING NUMBER: 10/13/20242025
1.A SEVERE TROPICAL STORM 13 (IVONE)

2.A POSITION 2025/03/10 AT 1200 UTC:
WITHIN 30 NM RADIUS OF POINT 20.0 S / 81.8 E
(TWENTY    DECIMAL ZERO   DEGREES SOUTH AND
EIGHTY ONE    DECIMAL EIGHT   DEGREES EAST)
MOVEMENT: SOUTH-WEST 6 KT

3.A DVORAK ANALYSIS: 3.5/3.5/D 0.5/6 H

4.A CENTRAL PRESSURE: 981 HPA
5.A MAX AVERAGE WIND SPEED (10 MN): 50 KT
RADIUS OF MAXIMUM WINDS (RMW): NIL

6.A EXTENSION OF WIND BY QUADRANTS (KM):
28 KT NE: 455 SE: 675 SW: 535 NW: 220
34 KT NE: 65 SE: 325 SW: 295 NW: 65
48 KT NE: 0 SE: 220 SW: 0 NW: 0
64 KT NE: 0 SE: 0 SW: 0 NW: 0

7.A FIRST CLOSED ISOBAR (PRESSURE / AVERAGE DIAM): 1009 HPA / 900 KM
8.A VERTICAL EXTENSION OF CYCLONE CIRCULATION: DEEP

1.B FORECASTS (WINDS RADII IN KM):
12H: 2025/03/11 00 UTC: 20.5 S / 80.3 E, VENT MAX= 045 KT, MODERATE
TROPICAL STORM
28 KT NE: 230 SE: 545 SW: 455 NW: 185
34 KT NE: 85 SE: 305 SW: 240 NW: 100

24H: 2025/03/11 12 UTC: 20.3 S / 77.7 E, VENT MAX= 040 KT, REMNANT
LOW
28 KT NE: 150 SE: 575 SW: 510 NW: 85
34 KT NE: 0 SE: 315 SW: 205 NW: 0

36H: 2025/03/12 00 UTC: 20.2 S / 74.5 E, VENT MAX= 040 KT, REMNANT
LOW
28 KT NE: 150 SE: 415 SW: 345 NW: 0
34 KT NE: 0 SE: 220 SW: 140 NW: 0

48H: 2025/03/12 12 UTC: 20.6 S / 71.4 E, VENT MAX= 035 KT, REMNANT
LOW
28 KT NE: 155 SE: 370 SW: 250 NW: 0
34 KT NE: 0 SE: 195 SW: 95 NW: 0

60H: 2025/03/13 00 UTC: 21.5 S / 68.4 E, VENT MAX= 030 KT, REMNANT
LOW
28 KT NE: 155 SE: 425 SW: 325 NW: 0

72H: 2025/03/13 12 UTC: 23.7 S / 66.6 E, VENT MAX= 030 KT, REMNANT
LOW
28 KT NE: 165 SE: 350 SW: 185 NW: 85

2.B LONGER-RANGE OUTLOOK:
96H: 2025/03/14 12 UTC: 31.5 S / 67.4 E, VENT MAX= 030 KT,
DISSIPATING
28 KT NE: 205 SE: 285 SW: 185 NW: 100


2.C ADDITIONAL INFORMATION:
T=CI=3.5

LITTLE CHANGE OVER THE LAST 6 HOURS IN IVONE'S CONVECTIVE ACTIVITY.
HOWEVER, IT CAN BE SEEN FROM THE ANIMATION OF CONVENTIONAL SATELLITE
IMAGES THAT THE LOW-LEVEL CENTER HAS BEEN DETACHING FROM THE MAIN
CONVECTION FOR SEVERAL HOURS NOW, UNDER THE EFFECT OF PERSISTENT
NORTHWESTERLY SHEAR ESTIMATED AT 25KT IN THE 250-450 HPA LAYER
(ACCORDING TO THE HAFS-A FINE MODEL). THE EFFECT OF WINDSHEAR IS
CLEARLY DEMONSTRATED BY THE AMSR-2 MICROWAVE PASS AT 0838Z AND THE
SSMIS-F18 PASS AT 1118Z. SUBJECTIVE DVORAK ESTIMATES AND OBJECTIVE
DATA (ASCAT-C FROM 0416Z) STILL SUGGEST STORM-FORCE WINDS IN THE
SYSTEM'S SOUTHERN SEMICIRCLE.

NO CHANGE IN TERMS OF TRACK FORECAST: IVONE IS CURRENTLY MOVING IN A
SOUTH-WESTERLY DIRECTION UNDER THE INFLUENCE OF THE RIDGE TO THE EAST
OF THE SYSTEM. TODAY, THE ARRIVAL OF THE SUBTROPICAL RIDGE TO THE
SOUTH SHOULD FAVOR A CHANGE IN TRAJECTORY TOWARDS THE WEST UNTIL
MID-WEEK. FROM THURSDAY ONWARDS, THE SYSTEM SHOULD MOVE
SOUTH-WESTWARDS, BYPASSING THE RIDGE TO THE NORTH-WEST AND THEN
PLUNGING FURTHER SOUTH.

IN TERMS OF INTENSITY, IVONE WILL REMAIN CLOSE TO CURRENT LEVELS FOR
THE NEXT 12/18H. BEYOND THIS, WESTERLY WINDSHEAR AND INTRUSIONS OF
DRY AIR SHOULD LEAD TO A SLOW FILLING IN OF IVONE OVER THE NEXT 5
DAYS. IT COULD STILL MAINTAIN STRONG WINDS OVER THE NEXT 48 HOURS IN
ITS SOUTHERN PART DUE TO THE GRADIENT EFFECT.

NO SIGNIFICANT IMPACT IS EXPECTED ON INHABITED LAND.=

Leonardo

TPXS10 PGTW 101445

A. TROPICAL CYCLONE 24S (IVONE)

B. 10/1430Z

C. 19.32S

D. 80.96E

E. SIX/MET9

F. T2.5/3.0/W0.5/24HRS  STT: S0.0/03HRS

G. IR/EIR

H. REMARKS: 63A/PBO PRLY ORGNZD LLCC/ANMTN. DENSE OVERCAST SHEARED
61NM FROM LLCC YIELDS A DT OF 1.5. MET YIELDS 3.0. PT YIELDS 2.5. DBO
PT.

I. ADDITIONAL POSITIONS:
   10/1110Z  19.13S  81.80E  SSMS


   RAE

---

TXXS28 KNES 101157
TCSSIO

A.  24S (IVONE)

B.  10/1115Z

C.  19.3S

D.  81.8E

E.  THREE/MET-9

F.  T3.0/3.5

G.  IR/EIR/VIS

H.  REMARKS...LLCC LOCATED LESS THAN 3/4 DEGREES FROM DG RESULTS IN A DT
OF 2.5. THE MET AND PT ARE 3.0 BASED ON A SLOW DEVELOPMENT TREND OVER
THE PAST 24 HOURS. THE FT IS BASED ON THE MET DUE TO SOME UNCERTAINTY
IN THE PRECISE LLCC POSITION.

I.  ADDL POSITIONS

    NIL


...COVERDALE

=

ygsj24

WTIO30 FMEE 101849
RSMC / TROPICAL CYCLONE CENTER / LA REUNION
TROPICAL CYCLONE FORECAST WARNING (SOUTH-WEST INDIAN OCEAN)

0.A WARNING NUMBER: 11/13/20242025
1.A MODERATE TROPICAL STORM 13 (IVONE)

2.A POSITION 2025/03/10 AT 1800 UTC:
WITHIN 30 NM RADIUS OF POINT 20.1 S / 81.2 E
(TWENTY    DECIMAL ONE   DEGREES SOUTH AND
EIGHTY ONE    DECIMAL TWO   DEGREES EAST)
MOVEMENT: SOUTH-WEST 6 KT

3.A DVORAK ANALYSIS: 3.5/3.5/S 0.0/6 H

4.A CENTRAL PRESSURE: 985 HPA
5.A MAX AVERAGE WIND SPEED (10 MN): 45 KT
RADIUS OF MAXIMUM WINDS (RMW): NIL

6.A EXTENSION OF WIND BY QUADRANTS (KM):
28 KT NE: 250 SE: 685 SW: 435 NW: 215
34 KT NE: 130 SE: 435 SW: 285 NW: 120

7.A FIRST CLOSED ISOBAR (PRESSURE / AVERAGE DIAM): 1009 HPA / 900 KM
8.A VERTICAL EXTENSION OF CYCLONE CIRCULATION: DEEP

1.B FORECASTS (WINDS RADII IN KM):
12H: 2025/03/11 06 UTC: 20.4 S / 79.1 E, VENT MAX= 040 KT, MODERATE
TROPICAL STORM
28 KT NE: 120 SE: 600 SW: 530 NW: 85
34 KT NE: 0 SE: 360 SW: 270 NW: 0

24H: 2025/03/11 18 UTC: 20.2 S / 76.1 E, VENT MAX= 040 KT, REMNANT
LOW
28 KT NE: 110 SE: 595 SW: 455 NW: 120
34 KT NE: 0 SE: 350 SW: 230 NW: 65

36H: 2025/03/12 06 UTC: 20.4 S / 73.0 E, VENT MAX= 035 KT, REMNANT
LOW
28 KT NE: 100 SE: 535 SW: 380 NW: 0
34 KT NE: 0 SE: 315 SW: 175 NW: 0

48H: 2025/03/12 18 UTC: 21.1 S / 70.0 E, VENT MAX= 035 KT, REMNANT
LOW
28 KT NE: 120 SE: 490 SW: 215 NW: 0
34 KT NE: 0 SE: 295 SW: 165 NW: 0

60H: 2025/03/13 06 UTC: 22.6 S / 67.9 E, VENT MAX= 035 KT, REMNANT
LOW
28 KT NE: 140 SE: 305 SW: 155 NW: 85
34 KT NE: 0 SE: 165 SW: 100 NW: 0

72H: 2025/03/13 18 UTC: 25.0 S / 66.8 E, VENT MAX= 035 KT, REMNANT
LOW
28 KT NE: 270 SE: 465 SW: 315 NW: 100
34 KT NE: 140 SE: 295 SW: 205 NW: 0

2.B LONGER-RANGE OUTLOOK:
96H: 2025/03/14 18 UTC: 32.8 S / 67.5 E, VENT MAX= 030 KT, REMNANT
LOW
28 KT NE: 445 SE: 490 SW: 215 NW: 165


2.C ADDITIONAL INFORMATION:
T=CI=3.5

LITTLE CHANGE OVER THE LAST 6 HOURS IN IVONE'S CONVECTIVE ACTIVITY.
THE SYSTEM REMAINS IN A SHEAR CONFIGURATION, WITH A LOW-LEVEL CENTER
AWAY FROM THE MAIN CONVECTION, DUE TO PERSISTENT NORTHWESTERLY SHEAR
ESTIMATED AT 25KT IN THE 250-450 HPA LAYER (USING THE HAFS-A
FINE-MESH MODEL). THE F-17 MICROWAVE IMAGE CLEARLY SHOWS THE EFFECT
OF THE SHEAR. THE PARTIAL ASCAT FROM 1552Z DOES NOT ALLOW US TO
MEASURE THE WINDS AT THE HEART OF THE SYSTEM. BUT DVORAK'S SUBJECTIVE
ESTIMATES STILL SUGGEST STORM-FORCE WINDS IN THE SYSTEM'S SOUTHERN
SEMICIRCLE.

NO CHANGE IN TERMS OF TRACK FORECAST: IVONE IS CURRENTLY MOVING IN A
SOUTH-WESTERLY DIRECTION UNDER THE INFLUENCE OF THE RIDGE TO THE EAST
OF THE SYSTEM. TODAY, THE ARRIVAL OF THE SUBTROPICAL RIDGE TO THE
SOUTH SHOULD FAVOR A CHANGE IN TRAJECTORY TOWARDS THE WEST UNTIL
MID-WEEK. FROM THURSDAY ONWARDS, THE SYSTEM SHOULD MOVE
SOUTH-WESTWARDS, BYPASSING THE RIDGE TO THE NORTH-WEST AND THEN
PLUNGING FURTHER SOUTH.

IN TERMS OF INTENSITY, IVONE WILL REMAIN CLOSE TO CURRENT LEVELS FOR
THE NEXT 12/18H. BEYOND THIS, WESTERLY WINDSHEAR AND INTRUSIONS OF
DRY AIR SHOULD LEAD TO A SLOW FILLING IN OF IVONE OVER THE NEXT 5
DAYS. IT COULD STILL MAINTAIN STRONG WINDS OVER THE NEXT 48 HOURS IN
ITS SOUTHERN PART DUE TO THE GRADIENT EFFECT.

NO SIGNIFICANT IMPACT IS EXPECTED ON INHABITED LAND.=

ygsj24

WTXS31 PGTW 102100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/TROPICAL CYCLONE 24S (IVONE) WARNING NR 006//
RMKS/
1. TROPICAL CYCLONE 24S (IVONE) WARNING NR 006   
   02 ACTIVE TROPICAL CYCLONES IN SOUTHIO
   MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE
   WIND RADII VALID OVER OPEN WATER ONLY
    ---
   WARNING POSITION:
   101800Z --- NEAR 20.2S 81.0E
     MOVEMENT PAST SIX HOURS - 230 DEGREES AT 08 KTS
     POSITION ACCURATE TO WITHIN 045 NM
     POSITION BASED ON CENTER LOCATED BY SATELLITE
   PRESENT WIND DISTRIBUTION:
   MAX SUSTAINED WINDS - 045 KT, GUSTS 055 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   RADIUS OF 034 KT WINDS - 005 NM NORTHEAST QUADRANT
                            295 NM SOUTHEAST QUADRANT
                            200 NM SOUTHWEST QUADRANT
                            005 NM NORTHWEST QUADRANT
   REPEAT POSIT: 20.2S 81.0E
    ---
   FORECASTS:
   12 HRS, VALID AT:
   110600Z --- 20.1S 78.9E
   MAX SUSTAINED WINDS - 045 KT, GUSTS 055 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   RADIUS OF 034 KT WINDS - 030 NM NORTHEAST QUADRANT
                            250 NM SOUTHEAST QUADRANT
                            190 NM SOUTHWEST QUADRANT
                            020 NM NORTHWEST QUADRANT
   VECTOR TO 24 HR POSIT: 270 DEG/ 13 KTS
    ---
   24 HRS, VALID AT:
   111800Z --- 20.0S 76.2E
   MAX SUSTAINED WINDS - 045 KT, GUSTS 055 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   RADIUS OF 034 KT WINDS - 000 NM NORTHEAST QUADRANT
                            220 NM SOUTHEAST QUADRANT
                            170 NM SOUTHWEST QUADRANT
                            000 NM NORTHWEST QUADRANT
   VECTOR TO 36 HR POSIT: 265 DEG/ 15 KTS
    ---
   36 HRS, VALID AT:
   120600Z --- 20.3S 73.0E
   MAX SUSTAINED WINDS - 045 KT, GUSTS 055 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   RADIUS OF 034 KT WINDS - 050 NM NORTHEAST QUADRANT
                            180 NM SOUTHEAST QUADRANT
                            120 NM SOUTHWEST QUADRANT
                            000 NM NORTHWEST QUADRANT
   VECTOR TO 48 HR POSIT: 250 DEG/ 15 KTS
    ---
   EXTENDED OUTLOOK:
   48 HRS, VALID AT:
   121800Z --- 21.4S 70.0E
   MAX SUSTAINED WINDS - 040 KT, GUSTS 050 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   DISSIPATING AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER
   RADIUS OF 034 KT WINDS - 050 NM NORTHEAST QUADRANT
                            150 NM SOUTHEAST QUADRANT
                            100 NM SOUTHWEST QUADRANT
                            000 NM NORTHWEST QUADRANT
   VECTOR TO 72 HR POSIT: 215 DEG/ 13 KTS
    ---
   72 HRS, VALID AT:
   131800Z --- 25.4S 66.7E
   MAX SUSTAINED WINDS - 035 KT, GUSTS 045 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   DISSIPATING AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER
   RADIUS OF 034 KT WINDS - 120 NM NORTHEAST QUADRANT
                            140 NM SOUTHEAST QUADRANT
                            060 NM SOUTHWEST QUADRANT
                            000 NM NORTHWEST QUADRANT
   VECTOR TO 96 HR POSIT: 175 DEG/ 13 KTS
    ---
   LONG RANGE OUTLOOK:
    ---
   96 HRS, VALID AT:
   141800Z --- 30.4S 67.3E
   MAX SUSTAINED WINDS - 035 KT, GUSTS 045 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   DISSIPATED AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER
   RADIUS OF 034 KT WINDS - 110 NM NORTHEAST QUADRANT
                            100 NM SOUTHEAST QUADRANT
                            020 NM SOUTHWEST QUADRANT
                            000 NM NORTHWEST QUADRANT
    ---
REMARKS:
102100Z POSITION NEAR 20.2S 80.5E.
10MAR25. TROPICAL CYCLONE 24S (IVONE), LOCATED APPROXIMATELY
929 NM SOUTH-SOUTHEAST OF DIEGO GARCIA, HAS TRACKED SOUTHWESTWARD
AT 08 KNOTS OVER THE PAST SIX HOURS.
MINIMUM CENTRAL PRESSURE AT 101800Z IS 996 MB.
MAXIMUM SIGNIFICANT WAVE HEIGHT AT 101800Z IS 31 FEET.
NEXT WARNINGS AT 110900Z AND 112100Z.REFER TO TROPICAL CYCLONE 25S
(JUDE) FINAL WARNING (WTXS32 PGTW). //
NNNN

1. WDXS31 PGTW 102100
   
2. MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
   
3. SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 24S (IVONE) WARNING NR
   
4. 006//
   
5. RMKS/
   
6. 1. FOR METEOROLOGISTS.
   
7. 2. 6 HOUR SUMMARY AND ANALYSIS.
   
8. 
   
9. SUMMARY:
   
10.    INITIAL POSITION: 20.2S 81.0E
    
11.    INITIAL INTENSITY: 45 KTS
    
12.    GEOGRAPHIC REFERENCE: 929 NM SOUTH-SOUTHEAST OF DIEGO GARCIA
    
13.    MOVEMENT PAST 6 HOURS: SOUTHWESTWARD AT 08 KTS
    
14.    SIGNIFICANT WAVE HEIGHT: 31 FEET
    
15. 
    
16. SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
    
17. ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS TROPICAL
    
18. CYCLONE (TC) 24S WITH A COMPLETELY EXPOSED LOW-LEVEL CIRCULATION
    
19. CENTER (LLCC) AS DEEP AND PERSISTENT CONVECTION HAS BECOME
    
20. INCREASINGLY DISLOCATED TO THE SOUTHEAST QUADRANT DUE TO THE
    
21. PRESENCE OF STRONG VERTICAL WIND SHEAR (VWS). WITH REGARD TO
    
22. UPPER-LEVEL SUPPORT, STRONG POLEWARD EXHAUST HAS CONTINUED, WITH
    
23. VISIBLE TRANSVERSE BANDING WRAPPING INTO A MID-LATITUDE JET FINGER
    
24. TO THE SOUTH AND RADIAL OUTFLOW STRIATIONS PULSING OUTWARD AND AWAY
    
25. FROM THE OFFSET CONVECTION. ALTHOUGH STRONG POLEWARD OUTFLOW HAS
    
26. HELPED MAINTAIN THE SYSTEMS INTENSITY, DRY-AIR ENTRAINMENT AND
    
27. HOSTILE VWS HAS CAPPED INTENSIFICATION TO 45 KTS. A RECENT 101647Z
    
28. ASCAT-C SCATTEROMETRY IMAGE HAS REVEALED AN ASYMMETRIC WIND FIELD,
    
29. RESTRICTING THE STRONGEST INTENSITIES TO THE SOUTHERN SEMICIRCLE.
    
30. THE INITIAL POSITION AND INTENSITY ARE ASSESSED WITH HIGH CONFIDENCE
    
31. BASED ON THE AFOREMENTIONED ASCAT-C IMAGE AND THE FULLY EXPOSED
    
32. LLCC ON ANIMATED EIR SATELLITE IMAGERY.
    
33. 
    
34. INITIAL WIND RADII BASIS: SCATTEROMETER DATA
    
35. 
    
36. CURRENT STEERING MECHANISM: DEEP-LAYER SUBTROPICAL RIDGE (STR)
    
37. POSITIONED TO THE EAST AND SOUTH
    
38. 
    
39. AGENCY DVORAK AND AUTOMATED FIXES:
    
40.    PGTW: T2.5 - 35 KTS
    
41.    KNES: T2.5 - 35 KTS
    
42.    DEMS: T2.5 - 35 KTS
    
43.    FMEE: T3.5 - 55 KTS
    
44.    FIMP: T3.0 - 45 KTS
    
45.    CIMSS SATCON: 44 KTS AT 101600Z
    
46.    CIMSS ADT: 35 KTS AT 101830Z
    
47.    CIMSS AIDT: 37 KTS AT 101830Z
    
48.    CIMSS D-MINT: 40 KTS AT 101309Z
    
49.    CIMSS D-PRINT: 37 KTS AT 101830Z
    
50. 
    
51. FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINAL
    
52.    VWS: 25-30 KTS
    
53.    SST: 26-27 CELSIUS
    
54.    OUTFLOW: STRONG POLEWARD
    
55.    OTHER FACTORS: DRY AIR ENTRAINMENT AROUND THE NORTHERN
    
56. SEMICIRCLE
    
57. 
    
58. ANALYSIS CONFIDENCE:
    
59.    INITIAL POSITION: HIGH
    
60.    INITIAL INTENSITY: HIGH
    
61.    INITIAL WIND RADII: HIGH
    
62. 
    
63. 3. FORECAST REASONING.
    
64. 
    
65. SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO
    
66. THE FORECAST FROM THE PREVIOUS WARNING.
    
67. 
    
68. FORECAST DISCUSSION: TC 24S IS FORECASTED TO CONTINUE ON A WESTWARD
    
69. TRACK ALONG THE NORTHERN PERIPHERY OF A BUILDING STR TO THE SOUTH
    
70. INTO TAU 36. AFTER TAU 36, THE SYSTEM WILL BEGIN ITS SOUTHWESTWARD
    
71. APPROACH TOWARD THE STR AXIS UNTIL TAU 72. AT THE SAME TIME, TC 24S
    
72. WILL BEGIN ITS INITIAL WEAKENING PHASE AS ENVIRONMENTAL CONDITIONS
    
73. BECOME LARGELY UNFAVORABLE FOR FURTHER INTENSIFICATION OR SUPPORT.
    
74. WHILE TC IVONE NEARS THE STR AXIS, THE UPPER-LEVEL OUTFLOW
    
75. MECHANISM WILL WEAKEN AS THE JET FINGER REPOSITIONS AND SHIFTS
    
76. SOUTHEASTWARD. WHILE THE CYCLONE ROUNDS THE STR AXIS AND BEGINS ITS
    
77. SOUTH-SOUTHEASTWARD TRACK AFTER TAU 72, SEA SURFACE TEMPERATURES
    
78. DECREASING TO BELOW 26 C, VERTICAL WIND SHEAR INCREASING TO
    
79. ABOVE 25 KTS, AND DRY AIR ENTRAINMENT WILL FURTHER WEAKEN THE
    
80. SYSTEM UNTIL TAU 96, RESULTING IN THE CYCLONES GRADUAL DISSIPATION.
    
81. 
    
82. 
    
83. MODEL DISCUSSION: NUMERICAL MODEL TRACK GUIDANCE REMAINS IN TIGHT
    
84. AGREEMENT, WITH A 116 CROSS-TRACK SPREAD AS THE SYSTEM BEGINS ITS
    
85. SOUTHWEST APPROACH TOWARD THE STR AXIS AT TAU 72. AFTER TAU 72, THE
    
86. ALONG-TRACK INCREASES SUBSTANTIALLY BETWEEN JTWC CONSENSUS MEMBERS
    
87. AS THE SYSTEM STARTS TO BECOME COMPLETELY ENVELOPED INTO THE
    
88. MID-LATITUDE WESTERLIES. DUE TO THE UNCERTAINTY IN THE INTERACTION
    
89. BETWEEN TC 24S AND THE MID-LATITUDE WESTERLIES, THE JTWC TRACK
    
90. FORECAST IS ASSESSED WITH HIGH CONFIDENCE UNTIL TAU 72, AND
    
91. MODERATE CONFIDENCE THEREAFTER. WITH REGARD TO INTENSITY,
    
92. CONFIDENCE REMAINS HIGH THAT INTENSITIES WILL REMAIN NEAR 45 KTS
    
93. UNTIL TAU 36. FOLLOWING TAU 36, NUMERICAL MODEL INTENSITY GUIDANCE
    
94. REMAINS IN GOOD AGREEMENT THROUGH THE REMAINDER OF THE FORECAST,
    
95. WITH AN EXPECTED AND STEADY WEAKENING PHASE AFTER TAU 36 AND UNTIL
    
96. COMPLETE DISSIPATION AT TAU 96.
    
97. 
    
98. FORECAST CONFIDENCE:
    
99.    TRACK 0 - 72 HR: HIGH
    
100.    TRACK 72-120 HR: MEDIUM
     
101.    INTENSITY 0 - 72 HR: HIGH
     
102.    INTENSITY 72-120 HR: MEDIUM//
     
103. NNNN

复制代码

yhh

WTIO30 FMEE 110031
RSMC / TROPICAL CYCLONE CENTER / LA REUNION
TROPICAL CYCLONE FORECAST WARNING (SOUTH-WEST INDIAN OCEAN)

0.A WARNING NUMBER: 12/13/20242025
1.A MODERATE TROPICAL STORM 13 (IVONE)

2.A POSITION 2025/03/11 AT 0000 UTC:
WITHIN 30 NM RADIUS OF POINT 20.1 S / 80.5 E
(TWENTY DECIMAL ONE DEGREES SOUTH AND
EIGHTY DECIMAL FIVE DEGREES EAST)
MOVEMENT: WEST-SOUTH-WEST 5 KT

3.A DVORAK ANALYSIS: 3.0/3.5/D 0.5/0 H

4.A CENTRAL PRESSURE: 995 HPA
5.A MAX AVERAGE WIND SPEED (10 MN): 40 KT
RADIUS OF MAXIMUM WINDS (RMW): NIL

6.A EXTENSION OF WIND BY QUADRANTS (KM):
28 KT NE: 280 SE: 750 SW: 715 NW: 280
34 KT NE: 0 SE: 555 SW: 380 NW: 0

7.A FIRST CLOSED ISOBAR (PRESSURE / AVERAGE DIAM): 1009 HPA / 900 KM
8.A VERTICAL EXTENSION OF CYCLONE CIRCULATION: DEEP

1.B FORECASTS (WINDS RADII IN KM):
12H: 2025/03/11 12 UTC: 20.4 S / 77.7 E, VENT MAX= 040 KT, REMNANT LOW
28 KT NE: 110 SE: 650 SW: 595 NW: 85
34 KT NE: 0 SE: 405 SW: 270 NW: 0

24H: 2025/03/12 00 UTC: 20.5 S / 74.8 E, VENT MAX= 040 KT, REMNANT LOW
28 KT NE: 110 SE: 640 SW: 530 NW: 120
34 KT NE: 0 SE: 390 SW: 260 NW: 55

36H: 2025/03/12 12 UTC: 20.8 S / 71.6 E, VENT MAX= 035 KT, REMNANT LOW
28 KT NE: 120 SE: 510 SW: 455 NW: 95
34 KT NE: 0 SE: 305 SW: 185 NW: 0

48H: 2025/03/13 00 UTC: 21.8 S / 69.0 E, VENT MAX= 035 KT, REMNANT LOW
28 KT NE: 175 SE: 455 SW: 280 NW: 95
34 KT NE: 0 SE: 280 SW: 165 NW: 0

60H: 2025/03/13 12 UTC: 24.0 S / 67.4 E, VENT MAX= 035 KT, REMNANT LOW
28 KT NE: 185 SE: 370 SW: 175 NW: 95
34 KT NE: 0 SE: 230 SW: 150 NW: 0

72H: 2025/03/14 00 UTC: 27.4 S / 66.7 E, VENT MAX= 035 KT, REMNANT LOW
28 KT NE: 295 SE: 370 SW: 230 NW: 110
34 KT NE: 120 SE: 240 SW: 165 NW: 0

2.B LONGER-RANGE OUTLOOK:
NIL

2.C ADDITIONAL INFORMATION:
T=3.0 CI=3.5

OVER THE PAST 6 HOURS, IVONE'S CONVECTIVE ACTIVITY HAS REMAINED STRONG,
WITH VERY COLD CLOUD TOPS. HOWEVER, THE SYSTEM IS IN AN INCREASINGLY
SHEARED CLOUD CONFIGURATION, WITH A LOW-LEVEL CENTER FAR REMOVED
FROM THE MAIN CONVECTION. THE RATHER OLD ASCAT IMAGE OF 1644Z STILL
MEASURED MAXIMUM WINDS OF ALMOST 50 KT IN THE CONVECTION IN THE
SOUTHEAST QUADRANT, BUT DVORAK'S SUBJECTIVE ESTIMATE HAS SINCE
DIMINISHED. THE T-NUMBER IS ESTIMATED AT 3.0 WITH MAXIMUM WINDS OF 40 KT.

NO CHANGE IN TERMS OF FORECAST TRACK: WITH THE ARRIVAL OF THE
SUBTROPICAL RIDGE TO THE SOUTH, IVONE WILL BE HEADING WEST UNTIL
MID-WEEK. FROM THURSDAY ONWARDS, THE SYSTEM IS SET TO MOVE
SOUTH-WESTWARDS, SKIRTING THE RIDGE FROM THE NORTH-WEST, BEFORE
PLUNGING FURTHER SOUTH.

IN TERMS OF INTENSITY, IVONE WILL REMAIN CLOSE TO CURRENT LEVELS FOR
THE NEXT HOURS. BEYOND THIS, WESTERLY WINDSHEAR AND INTRUSIONS OF DRY
AIR SHOULD LEAD TO A SLOW FILLING IN OF IVONE OVER THE NEXT 5 DAYS. IT
COULD STILL MAINTAIN STRONG WINDS OVER THE NEXT 48 HOURS IN ITS
SOUTHERN PART DUE TO THE GRADIENT EFFECT.

NO SIGNIFICANT IMPACT IS EXPECTED ON INHABITED LAND.

pocketbox

全球热带气旋监测公报
预报：柳龙生  签发：钱奇峰  2025 年 03 月 11 日 10 时
“伊沃娜”向偏西方向移动

时       间：11日08时（北京时）

海       域：南印度洋

命       名：“伊沃娜”，IVONE

中心位置：南纬20.1度、东经80.5度

强度等级：热带风暴

最大风力：8级（20米/秒，相当于我国的热带风暴级）

中心气压：995百帕

参考位置：毛里求斯路易港偏东方向约2400公里的洋面上

变化过程：过去24小时，“伊沃娜”由9级减弱到8级

预报结论：“伊沃娜”将以每小时20-25公里的速度向偏西方向移动，强度变化不大。


图1 卫星红外监测图像（北京时间2025年03月11日08时00分）

pocketbox

WTIO30 FMEE 110719
RSMC / TROPICAL CYCLONE CENTER / LA REUNION
TROPICAL CYCLONE FORECAST WARNING (SOUTH-WEST INDIAN OCEAN)

0.A WARNING NUMBER: 13/13/20242025
1.A MODERATE TROPICAL STORM 13 (IVONE)

2.A POSITION 2025/03/11 AT 0600 UTC:
WITHIN 40 NM RADIUS OF POINT 20.4 S / 79.2 E
(TWENTY    DECIMAL FOUR   DEGREES SOUTH AND
SEVENTY NINE    DECIMAL TWO   DEGREES EAST)
MOVEMENT: WEST-SOUTH-WEST 8 KT

3.A DVORAK ANALYSIS: 3.0/3.0/S 0.0/0 H

4.A CENTRAL PRESSURE: 1000 HPA
5.A MAX AVERAGE WIND SPEED (10 MN): 35 KT
RADIUS OF MAXIMUM WINDS (RMW): NIL

6.A EXTENSION OF WIND BY QUADRANTS (KM):
28 KT NE: 0 SE: 750 SW: 750 NW: 0
34 KT NE: 0 SE: 490 SW: 335 NW: 0

7.A FIRST CLOSED ISOBAR (PRESSURE / AVERAGE DIAM): 1009 HPA / 1100 KM
8.A VERTICAL EXTENSION OF CYCLONE CIRCULATION: DEEP

1.B FORECASTS (WINDS RADII IN KM):
12H: 2025/03/11 18 UTC: 20.4 S / 76.4 E, VENT MAX= 035 KT, REMNANT
LOW
28 KT NE: 0 SE: 600 SW: 480 NW: 0
34 KT NE: 0 SE: 370 SW: 215 NW: 0

24H: 2025/03/12 06 UTC: 20.6 S / 73.2 E, VENT MAX= 035 KT, REMNANT
LOW
28 KT NE: 0 SE: 595 SW: 390 NW: 0
34 KT NE: 0 SE: 350 SW: 250 NW: 0

36H: 2025/03/12 18 UTC: 21.4 S / 70.0 E, VENT MAX= 030 KT, FILLING UP
28 KT NE: 0 SE: 490 SW: 465 NW: 0

48H: 2025/03/13 06 UTC: 23.2 S / 68.1 E, VENT MAX= 030 KT, FILLING UP
28 KT NE: 100 SE: 390 SW: 195 NW: 0

60H: 2025/03/13 18 UTC: 25.8 S / 67.0 E, VENT MAX= 030 KT, FILLING UP
28 KT NE: 0 SE: 480 SW: 315 NW: 0

72H: 2025/03/14 06 UTC: 29.1 S / 67.2 E, VENT MAX= 025 KT, FILLING UP

2.B LONGER-RANGE OUTLOOK:
NIL

2.C ADDITIONAL INFORMATION:
T=3.0 CI=3.0

OVER THE PAST 6 HOURS, THE CONVECTIVE ACTIVITY ASSOCIATED WITH IVONE
HAS BEEN MAINTAINED BUT CONTINUES TO MOVE AWAY FROM THE CENTER UNDER
THE INFLUENCE OF A NORTHWESTERLY WIND SHEAR ANALYZED AT 20KT BY
CIMSS. THE 0315Z ASCAT PASS SHOWS THAT STRONG WINDS ARE EXCLUSIVELY
IN THE SOUTHERN SEMICIRCLE, WITH MAX WINDS OF 40KT. THE BEST TRACK
WILL BE MODIFIED IN THIS DIRECTION AT 12Z. IVONE IS THEREFORE
MAINTAINED AS A MODERATE TROPICAL STORM WITH WINDS OF 40KT.

IN TERMS OF TRACK, FEW CHANGES. UNDER THE INFLUENCE OF THE
SUBTROPICAL RIDGE TO THE SOUTH OF THE SYSTEM, IVONE WILL CONTINUE TO
MOVE WESTWARDS UNTIL TOMORROW. IVONE SHOULD THEN TURN SOUTHWARDS
WITHIN 48 HOURS, BYPASSING THE RIDGE AND MOVING AWAY TOWARDS SOUTHERN
LATITUDES.

IN TERMS OF INTENSITY, IVONE WILL REMAIN CLOSE TO CURRENT LEVELS FOR
THE NEXT HOURS. BEYOND THIS, WESTERLY WINDSHEAR AND INTRUSIONS OF DRY
AIR SHOULD LEAD TO A SLOW FILLING IN OF IVONE OVER THE NEXT 5 DAYS.
IT COULD STILL MAINTAIN STRONG WINDS OVER THE NEXT 48 HOURS IN ITS
SOUTHERN PART DUE TO THE GRADIENT EFFECT.

NO SIGNIFICANT IMPACT IS EXPECTED ON INHABITED LAND.

pocketbox

WTXS31 PGTW 110900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/TROPICAL CYCLONE 24S (IVONE) WARNING NR 007//
RMKS/
1. TROPICAL CYCLONE 24S (IVONE) WARNING NR 007   
   01 ACTIVE TROPICAL CYCLONE IN SOUTHIO
   MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE
   WIND RADII VALID OVER OPEN WATER ONLY
    ---
   WARNING POSITION:
   110600Z --- NEAR 20.3S 79.1E
     MOVEMENT PAST SIX HOURS - 265 DEGREES AT 11 KTS
     POSITION ACCURATE TO WITHIN 060 NM
     POSITION BASED ON CENTER LOCATED BY SATELLITE
   PRESENT WIND DISTRIBUTION:
   MAX SUSTAINED WINDS - 045 KT, GUSTS 055 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   RADIUS OF 034 KT WINDS - 000 NM NORTHEAST QUADRANT
                            275 NM SOUTHEAST QUADRANT
                            180 NM SOUTHWEST QUADRANT
                            000 NM NORTHWEST QUADRANT
   REPEAT POSIT: 20.3S 79.1E
    ---
   FORECASTS:
   12 HRS, VALID AT:
   111800Z --- 20.2S 76.5E
   MAX SUSTAINED WINDS - 045 KT, GUSTS 055 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   RADIUS OF 034 KT WINDS - 010 NM NORTHEAST QUADRANT
                            260 NM SOUTHEAST QUADRANT
                            170 NM SOUTHWEST QUADRANT
                            000 NM NORTHWEST QUADRANT
   VECTOR TO 24 HR POSIT: 265 DEG/ 15 KTS
    ---
   24 HRS, VALID AT:
   120600Z --- 20.5S 73.4E
   MAX SUSTAINED WINDS - 045 KT, GUSTS 055 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   RADIUS OF 034 KT WINDS - 020 NM NORTHEAST QUADRANT
                            190 NM SOUTHEAST QUADRANT
                            100 NM SOUTHWEST QUADRANT
                            000 NM NORTHWEST QUADRANT
   VECTOR TO 36 HR POSIT: 250 DEG/ 14 KTS
    ---
   36 HRS, VALID AT:
   121800Z --- 21.3S 70.6E
   MAX SUSTAINED WINDS - 045 KT, GUSTS 055 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   RADIUS OF 034 KT WINDS - 050 NM NORTHEAST QUADRANT
                            190 NM SOUTHEAST QUADRANT
                            070 NM SOUTHWEST QUADRANT
                            000 NM NORTHWEST QUADRANT
   VECTOR TO 48 HR POSIT: 230 DEG/ 16 KTS
    ---
   EXTENDED OUTLOOK:
   48 HRS, VALID AT:
   130600Z --- 23.3S 68.0E
   MAX SUSTAINED WINDS - 045 KT, GUSTS 055 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   RADIUS OF 034 KT WINDS - 070 NM NORTHEAST QUADRANT
                            160 NM SOUTHEAST QUADRANT
                            040 NM SOUTHWEST QUADRANT
                            000 NM NORTHWEST QUADRANT
   VECTOR TO 72 HR POSIT: 195 DEG/ 15 KTS
    ---
   72 HRS, VALID AT:
   140600Z --- 29.0S 66.3E
   MAX SUSTAINED WINDS - 040 KT, GUSTS 050 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   DISSIPATING AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER
   RADIUS OF 034 KT WINDS - 130 NM NORTHEAST QUADRANT
                            180 NM SOUTHEAST QUADRANT
                            030 NM SOUTHWEST QUADRANT
                            000 NM NORTHWEST QUADRANT
   VECTOR TO 96 HR POSIT: 155 DEG/ 22 KTS
    ---
   LONG RANGE OUTLOOK:
    ---
   96 HRS, VALID AT:
   150600Z --- 36.7S 70.9E
   MAX SUSTAINED WINDS - 030 KT, GUSTS 040 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   DISSIPATED AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER
    ---
REMARKS:
110900Z POSITION NEAR 20.3S 78.5E.
11MAR25. TROPICAL CYCLONE 24S (IVONE), LOCATED APPROXIMATELY 880
NM SOUTH-SOUTHEAST OF DIEGO GARCIA, HAS TRACKED WESTWARD AT 11
KNOTS OVER THE PAST SIX HOURS.
MINIMUM CENTRAL PRESSURE AT 110600Z IS 992 MB. MAXIMUM
SIGNIFICANT WAVE HEIGHT AT 110600Z IS 31 FEET. NEXT WARNINGS AT
112100Z AND 120900Z.
//
NNNN

1. WDXS31 PGTW 110900
   
2. MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
   
3. SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 24S (IVONE) WARNING NR
   
4. 007//
   
5. RMKS/
   
6. 1. FOR METEOROLOGISTS.
   
7. 2. 6 HOUR SUMMARY AND ANALYSIS.
   
8. 
   
9. SUMMARY:
   
10.    INITIAL POSITION: 20.3S 79.1E
    
11.    INITIAL INTENSITY: 45 KTS
    
12.    GEOGRAPHIC REFERENCE: 880 NM SOUTH-SOUTHEAST OF DIEGO GARCIA
    
13.    MOVEMENT PAST 6 HOURS: WESTWARD AT 11 KTS
    
14.    SIGNIFICANT WAVE HEIGHT: 31 FEET
    
15. 
    
16. SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
    
17. ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A SLIGHTLY
    
18. ELONGATED LOW-LEVEL CIRCULATION CENTER (LLCC) OF TROPICAL CYCLONE (TC)
    
19. 24S (IVONE). STRONG (30+ KTS) NORTHWESTERLY VERTICAL WIND SHEAR (VWS)
    
20. IS CAUSING THE DEEP CONVECTION TO TILT TOWARD THE SOUTHEAST QUADRANT
    
21. OF THE SYSTEM. THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE
    
22. BASED ON NEARLY FULLY EXPOSED LLCC TO THE NORTHWEST OF THE DEEP
    
23. CONVECTION. DRY AIR ORIGINATING OVER THE NORTHWESTERN SEMICIRCLE IS
    
24. MIXING INTO THE STRATOCUMULUS CLOUD LAYER, DETERIORATING THE CORE OF
    
25. THE TC. POLEWARD OUTFLOW REMAINS STRONG, WITH THE TAIL END OF THE JET
    
26. TO THE SOUTH.  THE INITIAL INTENSITY OF 45 KTS IS ASSESSED WITH HIGH
    
27. CONFIDENCE BASED ON THE DVORAK AGENCY FIXES, AS WELL AS THE 110305Z
    
28. METOP-B ASCAT IMAGE SHOWING A BAND OF 40 KTS WINDS THROUGHOUT THE
    
29. SOUTHERN PORTION OF THE WIND FIELD.
    
30. 
    
31. INITIAL WIND RADII BASIS: SCATTEROMETER DATA
    
32. 
    
33. CURRENT STEERING MECHANISM: DEEP-LAYER SUBTROPICAL RIDGE (STR) TO
    
34. THE SOUTH
    
35. 
    
36. AGENCY DVORAK AND AUTOMATED FIXES:
    
37.    PGTW: T3.0 - 45 KTS
    
38.    KNES: T2.5 - 35 KTS
    
39.    FMEE: T3.0 - 45 KTS
    
40.    FIMP: T3.0 - 45 KTS
    
41.    CIMSS SATCON: 48 KTS AT 110354Z
    
42.    CIMSS ADT: 32 KTS AT 110600Z
    
43.    CIMSS AIDT: 31 KTS AT 110500Z
    
44.    CIMSS D-MINT: 31 KTS AT 110116Z
    
45.    CIMSS D-PRINT: 31 KTS AT 110600Z
    
46. 
    
47. FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINAL
    
48.    VWS: 30+ KTS
    
49.    SST: 26-27 CELSIUS
    
50.    OUTFLOW: STRONG POLEWARD
    
51.    OTHER FACTORS: DRY AIR ENTRAINMENT FROM THE NORTHWEST
    
52. 
    
53. ANALYSIS CONFIDENCE:
    
54.    INITIAL POSITION: HIGH
    
55.    INITIAL INTENSITY: HIGH
    
56.    INITIAL WIND RADII: HIGH
    
57. 
    
58. 3. FORECAST REASONING.
    
59. 
    
60. SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO
    
61. THE FORECAST FROM THE PREVIOUS WARNING.
    
62. 
    
63. FORECAST DISCUSSION: TC 24S IS FORECAST TO CONTINUE TRACKING
    
64. WESTWARD, UNDER THE INFLUENCE OF THE STEERING STR TO THE SOUTH. AS
    
65. THE RIDGE BUILDS AND MOVES EASTWARD, THE SYSTEM IS EXPECTED TO
    
66. FOLLOW ITS WESTERN PERIPHERY AND BEGIN TURNING SOUTHWESTWARD AROUND
    
67. TAU 24. THE SYSTEM WILL THEN ROUND THE AXIS OF THE STR BY TAU
    
68. 72 AND BECOME POSITIONED UNDERNEATH THE UPPER-LEVEL WESTERLIES.
    
69. AFTER THAT, TC 24S WILL TURN SOUTHEASTWARD AND IS FORECAST TO
    
70. DISSIPATE BY TAU 96, JUST AHEAD OF AN UPPER LEVEL JET MAXIMUM. TC
    
71. IVONE IS FORECAST TO MAINTAIN INTENSITY OVER THE NEXT 48 HOURS
    
72. UNDER THE IMPACTS OF MARGINAL ENVIRONMENTAL CONDITIONS. SEA
    
73. SURFACE TEMPERATURES (SST) WILL REMAIN WARM (26-27 C), OFFSET BY THE
    
74. WEAKENING UPPER-LEVEL OUTFLOW, STRONG VWS AND CONTINUOUS DRY AIR
    
75. ENTRAINMENT. AFTER TAU 48, TC 24S WILL ENTER AN AREA OF WEAKER VWS,
    
76. OFFSET HOWEVER BY COOLING SST, LEADING TO SLIGHT WEAKENING OF THE
    
77. SYSTEM. AFTER TAU 72, THE VWS WILL START TO INCREASE AGAIN, WHICH
    
78. COMBINED WITH SST DROPPING BELOW 25 C WILL LEAD TO THE DISSIPATION OF
    
79. TC 24S, AS IT ALSO APPROACHES THE BAROCLINIC ZONE TO THE SOUTH.
    
80. 
    
81. MODEL DISCUSSION: NUMERICAL MODEL TRACK GUIDANCE IS IN FAIR
    
82. AGREEMENT WITH ALL MODELS MATCHING IN REGARD TO THE STEERING MECHANISM
    
83. AND THE RECURVING MOTION OF THE SYSTEM. CROSS-TRACK SPREAD AT TAU 72
    
84. HOWEVER, IS OVER 230 NM, LEADING TO A MEDIUM CONFIDENCE OF THE TRACK
    
85. ASSESSMENT. TWO MAJOR OUTLIERS ARE ECMWF AND NAVGEM ON EACH SIDE OF
    
86. THE LONGITUDINAL SPECTRUM. EXCLUDING THE TWO MODELS FROM TRACK
    
87. GUIDANCE NARROWS DOWN THE CROSS-TRACK SPREAD TO 130 NM AND JTWC
    
88. FORECAST IS LAID CLOSE TO THE MULTI-MODEL CONSENSUS WITHIN THAT
    
89. SPREAD. LONG TERM TRACK IS ALSO ASSESSED WITH MEDIUM CONFIDENCE, AS
    
90. THE CROSS-TRACK SPREAD REMAINS JUST ABOVE 100 NM AT TAU 96. INTENSITY
    
91. FORECAST IS ASSESSED WITH MEDIUM CONFIDENCE THROUGHOUT THE FORECAST
    
92. PERIOD, DRIVEN BY A DIFFERING TIMELINE OF DISSIPATION, AMONG THE
    
93. CONSENSUS MODEL MEMBERS. COAMPS-TC AND HAFS MAINTAIN 45-55
    
94. INTENSITY THROUGHOUT TAU 84 AND DISSIPATE THE SYSTEM AROUND TAU
    
95. 120, WHILE GFS INDICATES WEAKENING TO 35 KTS AS SOON AS TAU
    
96. 36.
    
97. 
    
98. FORECAST CONFIDENCE:
    
99.    TRACK 0 - 72 HR: MEDIUM
    
100.    TRACK 72-120 HR: MEDIUM
     
101.    INTENSITY 0 - 72 HR: MEDIUM
     
102.    INTENSITY 72-120 HR: MEDIUM//
     
103. NNNN

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