科科斯群岛西南三级强热带气旋“詹纳”(11U/12S.Jenna) - JTWC:90KT

ygsj24

WTXS31 PGTW 062100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/TROPICAL CYCLONE 12S (JENNA) WARNING NR 005//
RMKS/
1. TROPICAL CYCLONE 12S (JENNA) WARNING NR 005   
   01 ACTIVE TROPICAL CYCLONE IN SOUTHIO
   MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE
   WIND RADII VALID OVER OPEN WATER ONLY
    ---
   WARNING POSITION:
   061800Z --- NEAR 16.7S 93.6E
     MOVEMENT PAST SIX HOURS - 235 DEGREES AT 07 KTS
     POSITION ACCURATE TO WITHIN 060 NM
     POSITION BASED ON CENTER LOCATED BY SATELLITE
   PRESENT WIND DISTRIBUTION:
   MAX SUSTAINED WINDS - 080 KT, GUSTS 100 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   RADIUS OF 064 KT WINDS - 020 NM NORTHEAST QUADRANT
                            020 NM SOUTHEAST QUADRANT
                            020 NM SOUTHWEST QUADRANT
                            000 NM NORTHWEST QUADRANT
   RADIUS OF 050 KT WINDS - 040 NM NORTHEAST QUADRANT
                            050 NM SOUTHEAST QUADRANT
                            035 NM SOUTHWEST QUADRANT
                            000 NM NORTHWEST QUADRANT
   RADIUS OF 034 KT WINDS - 090 NM NORTHEAST QUADRANT
                            140 NM SOUTHEAST QUADRANT
                            085 NM SOUTHWEST QUADRANT
                            060 NM NORTHWEST QUADRANT
   REPEAT POSIT: 16.7S 93.6E
    ---
   FORECASTS:
   12 HRS, VALID AT:
   070600Z --- 17.5S 92.3E
   MAX SUSTAINED WINDS - 065 KT, GUSTS 080 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   RADIUS OF 064 KT WINDS - 000 NM NORTHEAST QUADRANT
                            010 NM SOUTHEAST QUADRANT
                            010 NM SOUTHWEST QUADRANT
                            000 NM NORTHWEST QUADRANT
   RADIUS OF 050 KT WINDS - 010 NM NORTHEAST QUADRANT
                            020 NM SOUTHEAST QUADRANT
                            020 NM SOUTHWEST QUADRANT
                            010 NM NORTHWEST QUADRANT
   RADIUS OF 034 KT WINDS - 060 NM NORTHEAST QUADRANT
                            130 NM SOUTHEAST QUADRANT
                            090 NM SOUTHWEST QUADRANT
                            050 NM NORTHWEST QUADRANT
   VECTOR TO 24 HR POSIT: 245 DEG/ 06 KTS
    ---
   24 HRS, VALID AT:
   071800Z --- 18.0S 91.1E
   MAX SUSTAINED WINDS - 050 KT, GUSTS 065 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   RADIUS OF 050 KT WINDS - 000 NM NORTHEAST QUADRANT
                            030 NM SOUTHEAST QUADRANT
                            020 NM SOUTHWEST QUADRANT
                            000 NM NORTHWEST QUADRANT
   RADIUS OF 034 KT WINDS - 020 NM NORTHEAST QUADRANT
                            110 NM SOUTHEAST QUADRANT
                            080 NM SOUTHWEST QUADRANT
                            040 NM NORTHWEST QUADRANT
   VECTOR TO 36 HR POSIT: 265 DEG/ 07 KTS
    ---
   36 HRS, VALID AT:
   080600Z --- 18.1S 89.6E
   MAX SUSTAINED WINDS - 040 KT, GUSTS 050 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   RADIUS OF 034 KT WINDS - 010 NM NORTHEAST QUADRANT
                            100 NM SOUTHEAST QUADRANT
                            080 NM SOUTHWEST QUADRANT
                            020 NM NORTHWEST QUADRANT
   VECTOR TO 48 HR POSIT: 275 DEG/ 08 KTS
    ---
   EXTENDED OUTLOOK:
   48 HRS, VALID AT:
   081800Z --- 17.9S 87.9E
   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 - 010 NM NORTHEAST QUADRANT
                            100 NM SOUTHEAST QUADRANT
                            060 NM SOUTHWEST QUADRANT
                            010 NM NORTHWEST QUADRANT
   VECTOR TO 72 HR POSIT: 270 DEG/ 09 KTS
    ---
   72 HRS, VALID AT:
   091800Z --- 17.9S 84.0E
   MAX SUSTAINED WINDS - 030 KT, GUSTS 040 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   DISSIPATED AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER
    ---
REMARKS:
062100Z POSITION NEAR 16.9S 93.3E.
06JAN26. TROPICAL CYCLONE 12S (JENNA), LOCATED APPROXIMATELY 331
NM SOUTHWEST OF THE COCOS ISLANDS, HAS TRACKED SOUTHWESTWARD AT
07 KNOTS OVER THE PAST SIX HOURS.
MINIMUM CENTRAL PRESSURE AT 061800Z IS 976 MB. MAXIMUM
SIGNIFICANT WAVE HEIGHT AT 061800Z IS 30 FEET. NEXT WARNINGS AT
070900Z AND 072100Z.//
NNNN

1. WDXS31 PGTW 062100
   
2. MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
   
3. SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 12S (JENNA) WARNING NR
   
4. 005//
   
5. RMKS/
   
6. 1. FOR METEOROLOGISTS.
   
7. 2. 6 HOUR SUMMARY AND ANALYSIS.
   
8. 
   
9. SUMMARY:
   
10.    INITIAL POSITION: 16.7S 93.6E
    
11.    INITIAL INTENSITY: 80 KTS
    
12.    GEOGRAPHIC REFERENCE: 331 NM SOUTHWEST OF THE COCOS ISLANDS
    
13.    MOVEMENT PAST 6 HOURS: SOUTHWESTWARD AT 07 KTS
    
14.    SIGNIFICANT WAVE HEIGHT: 30 FEET
    
15. 
    
16. SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
    
17. TROPICAL CYCLONE (TC) 12S (JENNA) PEAKED IN INTENSITY BETWEEN 0600Z
    
18. AND 1200Z LAST NIGHT OF APPROXIMATELY 90 KNOTS. SUBSEQUENTLY, THE
    
19. SYSTEM HAS BEGUN TO WEAKEN; THE CURRENT RATE OF WEAKENING IS GRADUAL,
    
20. ALTHOUGH A MORE RAPID DECLINE IN INTENSITY IS IMMINENT. ANIMATED
    
21. ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS A SYMMETRICAL
    
22. CENTRAL DENSE OVERCAST (CDO) OBSCURING A SUBSTANTIAL PORTION OF THE
    
23. UNDERLYING LOWER-LEVEL STRUCTURE. CLOUD TOP TEMPERATURES WITHIN THE
    
24. CDO HAVE WARMED SIGNIFICANTLY OVER THE PAST SIX HOURS AND AN EYE IS
    
25. NO LONGER DISCERNIBLE. ANALYSIS OF THE OUTERMOST BANDING FEATURES IN
    
26. ANIMATED SHORTWAVE INFRARED (SWIR) IMAGERY SUGGESTS INDICATES THE
    
27. ONSET OF VORTEX DECOUPLING, AS TRACING OF THE BANDING FEATURES
    
28. INDICATES THE LOW LEVEL CIRCULATION CENTER (LLCC) IS POSITIONED ON
    
29. THE NORTHERN EDGE OF THE CDO RATHER THAN BEING CENTRALLY EMBEDDED. A
    
30. 061559Z ASCAT-C PASS REVEALED AN INCREASINGLY ASYMMETRIC WIND FIELD,
    
31. WITH INCREASING NORTHERLY SHEAR BEGINNING TO IMPINGE ON THE SYSTEM,
    
32. AND DECREASING THE EXTENT OF THE WIND FIELD ON THE NORTHERN
    
33. PERIPHERY, WHILE EXPANDING IT TO THE SOUTH. THE INITIAL POSITION IS
    
34. ASSESSED WITH MEDIUM CONFIDENCE DUE TO THE OBSCURED LLCC AND A LACK OF
    
35. RECENT MICROWAVE IMAGERY. THE INITIAL INTENSITY IS ASSESSED WITH
    
36. MEDIUM CONFIDENCE BASED ON A BLEND OF THE SUBJECTIVE AND OBJECTIVE
    
37. INTENSITY ESTIMATES NOTED BELOW. ENVIRONMENTAL CONDITIONS ARE
    
38. MARGINALLY FAVORABLE, CHARACTERIZED BY MARGINAL (26-27C) SSTS,
    
39. STRONG POLEWARD OUTFLOW ALOFT AND LOW VWS, OFFSET BY HIGH MID-LEVEL
    
40. SHEAR AND MID-LEVEL DRY AIR ENTRAINMENT.
    
41. 
    
42. INITIAL WIND RADII BASIS: SCATTEROMETER DATA
    
43. 
    
44. CURRENT STEERING MECHANISM: WESTERN PERIPHERY OF A DEEP-LAYER
    
45. SUBTROPICAL RIDGE (STR) TO THE EAST.
    
46. 
    
47. AGENCY DVORAK AND AUTOMATED FIXES:
    
48.    PGTW: T5.0 - 90 KTS
    
49.    DEMS: T5.0 - 90 KTS
    
50.    APRF: T4.5 - 77 KTS
    
51.    CIMSS SATCON: 71 KTS AT 061827Z
    
52.    CIMSS ADT: 87 KTS AT 061730Z
    
53.    CIMSS AIDT: 77 KTS AT 061730Z
    
54.    CIMSS D-PRINT: 85 KTS AT 061830Z
    
55. 
    
56. FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE
    
57.    VWS: 10-15 KTS
    
58.    SST: 26-27 CELSIUS
    
59.    OUTFLOW: STRONG POLEWARD
    
60.    OTHER FACTORS: STRONG MID-LEVEL SHEAR, DRY MID-LEVEL AIR TO THE
    
61. NORTHEAST.
    
62. 
    
63. ANALYSIS CONFIDENCE:
    
64.    INITIAL POSITION: MEDIUM
    
65.    INITIAL INTENSITY: MEDIUM
    
66.    INITIAL WIND RADII: HIGH
    
67. 
    
68. 3. FORECAST REASONING.
    
69. 
    
70. SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO
    
71. THE FORECAST FROM THE PREVIOUS WARNING.
    
72. 
    
73. FORECAST DISCUSSION: TC 12S HAS TRACKED SOUTHWESTWARD OVER THE PAST
    
74. 12 HOURS, ALONG THE WESTERN FLANK OF A DEEP-LAYER STR CENTERED TO THE
    
75. EAST. THIS RIDGE IS SLOWLY RECEDING TOWARD THE SOUTHEAST, WEAKENING
    
76. THE STEERING GRADIENT AND RESULTING IN A SLIGHT DECELERATION, THOUGH
    
77. NO SIGNIFICANT CHANGE IN THE TRACK DIRECTION IS EXPECTED FOR THE NEXT
    
78. 12 TO 24 HOURS. AS NOTED ABOVE, THE SYSTEM HAS ALREADY BEGUN TO
    
79. WEAKEN AS INCREASING SHEAR AND DRY AIR ENTRAINMENT BEGIN TO EXERT
    
80. THEIR EFFECTS. OVER THE NEXT 12 TO 24 HOURS, BOTH OF THESE ADVERSE
    
81. PARAMETERS ARE EXPECTED TO INCREASE SHARPLY, WITH SHEAR FORECAST TO
    
82. EXCEED 35 KNOTS BY TAU 24, WHILE DRY AIR WILL COMPLETELY ENGULF THE
    
83. SYSTEM FROM THE NORTHWEST BY THE SAME FORECAST PERIOD. THE VORTEX IS
    
84. EXPECTED TO FULLY DECOUPLE BY TAU 24, AND AS ITS VERTICAL DEPTH
    
85. DECREASES, THE REMNANT LLCC WILL COME UNDER THE STEERING INFLUENCE OF
    
86. THE EASTERLY LOW-LEVEL FLOW ALONG THE NORTHERN PERIPHERY OF A STRONG
    
87. RIDGE TO THE SOUTH. AS THE SYSTEM TRACKS WESTWARD, IT WILL RAPIDLY
    
88. WEAKEN, WITH DISSIPATION EXPECTED NO LATER THAN TAU 72, AND POSSIBLY
    
89. AS EARLY AS TAU 60.
    
90. 
    
91. MODEL DISCUSSION: DETERMINISTIC TRACK GUIDANCE EXHIBITS A HIGH DEGREE
    
92. OF CONSENSUS ON THE TRACK SCENARIO. ALL MEMBERS OF THE CONSENSUS
    
93. PACKAGE, AS WELL AS THE ENSEMBLES AND AI MODELS, ARE CONFINED TO A
    
94. GRADUALLY EXPANDING ENVELOPE WHICH INCREASES TO APPROXIMATELY 125NM
    
95. BY TAU 72. THE NAVGEM IS POSITIONED ON THE NORTHERN EXTENT OF THE
    
96. ENVELOPE, AND ECMWF ON THE SOUTHERN EXTENT. CONSISTENT WITH THE PAST
    
97. SEVERAL MODEL RUNS, ALONG-TRACK SPREAD INCREASES AFTER THE SYSTEM
    
98. TURNS WESTWARD; HOWEVER, THE SPREAD HAS DECREASED SOMEWHAT, DOWN TO
    
99. APPROXIMATELY 140NM BETWEEN THE FAST GEFS MEAN AND THE SLOW ECMWF.
    
100. THE JTWC FORECAST IS POSITIONED IN CLOSE AGREEMENT WITH THE MULTI-
     
101. MODEL CONSENSUS MEAN AND THE GDM FGN3 TRACKER WITH HIGH CONFIDENCE.
     
102. INTENSITY GUIDANCE CONCURS ON A RAPID WEAKENING TREND THROUGH TAU 48,
     
103. FOLLOWED BY A MORE GRADUAL WEAKENING THEREAFTER AS THE SYSTEM
     
104. PERSISTS AT LOW INTENSITY BEFORE FINALLY DISSIPATING. THE JTWC
     
105. FORECAST IS POSITIONED NEAR THE CONSENSUS MEAN WITH HIGH CONFIDENCE,
     
106. WITH THE ACKNOWLEDGMENT THAT THE SYSTEM IS LIKELY TO DISSIPATE PRIOR
     
107. TO THE TAU 72 FORECAST POINT.
     
108. 
     
109. FORECAST CONFIDENCE:
     
110.    TRACK 00-72 HR: HIGH
     
111.    INTENSITY 00-72 HR: HIGH//
     
112. NNNN

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IDW27600
TROPICAL CYCLONE TECHNICAL BULLETIN: AUSTRALIA - WESTERN REGION
Issued by AUSTRALIAN BUREAU OF METEOROLOGY TROPICAL CYCLONE WARNING CENTRE
at: 0056 UTC 07/01/2026
Name: Tropical Cyclone Jenna
Identifier: 11U
Data At: 0000 UTC
Latitude: 17.4S
Longitude: 93.1E
Location Accuracy: within 30nm (55 km)
Movement Towards: southwest (219 deg)
Speed of Movement: 8 knots (14 km/h)
Maximum 10-Minute Wind: 60 knots (110 km/h)
Maximum 3-Second Wind Gust: 85 knots (155 km/h)
Central Pressure: 979 hPa
Radius of 34-knot winds NE quadrant: 60 nm (110 km)
Radius of 34-knot winds SE quadrant: 110 nm (205 km)
Radius of 34-knot winds SW quadrant: 100 nm (185 km)
Radius of 34-knot winds NW quadrant: 50 nm (95 km)
Radius of 48-knot winds NE quadrant: 25 nm (45 km)
Radius of 48-knot winds SE quadrant: 50 nm (95 km)
Radius of 48-knot winds SW quadrant: 40 nm (75 km)
Radius of 48-knot winds NW quadrant: 25 nm (45 km)
Radius of 64-knot winds:   nm (  km)
Radius of Maximum Winds: 15 nm (30 km)
Dvorak Intensity Code: T4.0/4.0/S0.0/24HRS STT:W0.5/6HRS
Pressure of outermost isobar: 1006 hPa
Radius of outermost closed isobar: 120 nm (220 km)
FORECAST DATA
Date/Time    : Location    : Loc. Accuracy: Max Wind   : Central Pressure
(UTC)        : degrees     :      nm  (km): knots(km/h): hPa
+06:  07/0600: 18.0S  92.2E:     040 (075):  055  (100):  986
+12:  07/1200: 18.3S  91.5E:     050 (095):  050  (095):  988
+18:  07/1800: 18.3S  90.6E:     060 (110):  045  (085):  991
+24:  08/0000: 18.2S  89.9E:     060 (115):  040  (075):  995
+36:  08/1200: 17.8S  88.1E:     070 (130):  035  (065):  999
+48:  09/0000: 17.7S  86.0E:     080 (145):  030  (055): 1002
+60:  09/1200:             :              :            :     
+72:  10/0000:             :              :            :     
+96:  11/0000:             :              :            :     
+120: 12/0000:             :              :            :     
REMARKS:
Severe Tropical Cyclone Jenna (11U) has peaked and is now weakening.  

The location of Jenna was estimated using EIR and VIS imagery with only low to
moderate confidence, there have been no recent microwave passes.

Intensity is analysed at 60 kn based on Dvorak and objective guidance.

Dvorak analysis: DT=4.0 based on embedded centre pattern (DG) following earlier
eye patterns. MET=3.0 based on a W+ 24-hour trend with 0.5 PAT adjustment to
3.5. FT/CI=4.0 now that DT has been steady 6 hours. Objective guidance at 2300
UTC (1-minute mean): CIMSS ADT 74 kn (FT/CI=3.8/4.4), AiDT 64 kn, DPRINT 53 kn,
SATCON (2130 UTC) 73 kn.

Jenna is now moving over cooler SSTs and is being affected by increased
vertical wind shear, the cloud structure has become less organised with greatly
reduced cold cloud tops. Total Precipitable Water (TPW) shows drier air has
moved into the circulation and from now the north to northwest wind shear
should increase and bring further drier air into the circulation. Weakening
should become more rapid during Wednesday as a result. Gales are likely to
persist longer south of the centre during Thursday aided by its movement and
the broadscale forcing from the ridge to the south.  

Jenna is currently being steered towards the southwest by a mid-level ridge to
the east. This should continue in the short term then guidance shows good
agreement in the forecast becoming more westwards later Wednesday as the
steering becomes more shallow. Jenna is forecast to move west of 90E out of the
Australian Region during Thursday.  

Copyright Commonwealth of Australia
==
The next bulletin for this system will be issued by: 07/0730 UTC.

---

IDW24000
Australian Bureau of Meteorology
Tropical Cyclone Warning Centre

TROPICAL CYCLONE INFORMATION BULLETIN
Issued at 8:48 am WST on Wednesday 7 January 2026

Tropical Cyclone Jenna (Category 2) was located at 8:00 am AWST (6:30 am CCT)
near 17.4S 93.1E,
that is 710 km southwest of Cocos (Keeling) Islands moving southwest at 14
kilometres per hour.

Severe Tropical Cyclone Jenna (11U) is continuing to move southwest into the
Indian Ocean. Jenna has peaked in intensity and is now weakening, it is likely
to decrease below tropical cyclone strength during Thursday as it leaves the
Australian Region.

The next Information Bulletin will be issued at 3:00 pm AWST Wednesday 07
January. .

	Time (AWST)	Intensity Category	Latitude (decimal deg.)	Longitude (decimal deg.)	Estimated Position Accuracy (km)
0hr	8 am January 7	2	17.4S	93.1E	55
+6hr	2 pm January 7	2	18.0S	92.2E	75
+12hr	8 pm January 7	2	18.3S	91.5E	95
+18hr	2 am January 8	1	18.3S	90.6E	110
+24hr	8 am January 8	tropical low	18.2S	89.9E	115
+36hr	8 pm January 8	tropical low	17.8S	88.1E	130
+48hr	8 am January 9	tropical low	17.7S	86.0E	145
+60hr	8 pm January 9	tropical low	XXX	XXX	XXX
+72hr	8 am January 10	tropical low	XXX	XXX	XXX

pocketbox

全球热带气旋监测公报
预报：曹越男  签发：王海平  2026 年 01 月 07 日 10 时
“詹纳”向西南方向移动

时  间: 7日08时（北京时）

海  域: 澳大利亚附近海域

命  名: “詹纳”，JENNA

中心位置: 南纬17.4度，东经93.1度

强度等级: 二级热带气旋

最大风力: 11级，18米/秒，相当于我国的强热带风暴级

中心气压: 979百帕

参考位置: 距离科科斯群岛西南方向约680公里

变化过程: 过去24小时，“詹纳”强度由10级加强为13级又减弱为11级

预报结论: “詹纳”将以每小时15公里左右的速度向西南方向移动，强度逐渐减弱



图1  卫星红外监测图像（北京时间2026年1月7日08时00分）

pocketbox

IDW27600
TROPICAL CYCLONE TECHNICAL BULLETIN: AUSTRALIA - WESTERN REGION
Issued by AUSTRALIAN BUREAU OF METEOROLOGY TROPICAL CYCLONE WARNING CENTRE
at: 0650 UTC 07/01/2026
Name: Tropical Cyclone Jenna
Identifier: 11U
Data At: 0600 UTC
Latitude: 18.0S
Longitude: 92.4E
Location Accuracy: within 30nm (55 km)
Movement Towards: southwest (228 deg)
Speed of Movement: 9 knots (17 km/h)
Maximum 10-Minute Wind: 55 knots (100 km/h)
Maximum 3-Second Wind Gust: 75 knots (140 km/h)
Central Pressure: 989 hPa
Radius of 34-knot winds NE quadrant: 50 nm (95 km)
Radius of 34-knot winds SE quadrant: 110 nm (205 km)
Radius of 34-knot winds SW quadrant: 90 nm (165 km)
Radius of 34-knot winds NW quadrant: 50 nm (95 km)
Radius of 48-knot winds NE quadrant: 0 nm (0 km)
Radius of 48-knot winds SE quadrant: 55 nm (100 km)
Radius of 48-knot winds SW quadrant: 50 nm (95 km)
Radius of 48-knot winds NW quadrant: 40 nm (75 km)
Radius of 64-knot winds:   nm (  km)
Radius of Maximum Winds: 15 nm (30 km)
Dvorak Intensity Code: T3.0/4.0/W1.0/24HRS STT:W1.0/06HRS
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:  07/1200: 18.2S  91.5E:     040 (080):  050  (095):  990
+12:  07/1800: 18.3S  90.7E:     050 (095):  045  (085):  994
+18:  08/0000: 18.3S  90.0E:     060 (110):  040  (075):  997
+24:  08/0600: 18.0S  89.1E:     060 (115):  035  (065): 1001
+36:  08/1800: 17.6S  87.1E:     070 (130):  030  (055): 1004
+48:  09/0600:             :              :            :     
+60:  09/1800:             :              :            :     
+72:  10/0600:             :              :            :     
+96:  11/0600:             :              :            :     
+120: 12/0600:             :              :            :     
REMARKS:
Tropical Cyclone Jenna (11U) is weakening rapidly over the open waters of the
Indian Ocean.  

The location of Jenna was extrapolated from a morning microwave pass which gave
a good fix. Locating the system using VIS/EIR imagery is difficult now most of
the deep convection has gone and there is no exposed  low level centre.

Intensity is analysed at 55 kn based on Dvorak and objective guidance.

Dvorak analysis: DT=3.0 based on curved band and shear patterns. MET=3.5 based
on a W+ 24-hour trend with -0.5 PAT adjustment to 3.0. FT/CI=3.0/4.0. Objective
guidance at  0530 UTC (1-minute mean): CIMSS ADT 65 kn (FT/CI=3.2/4.0), AiDT 62
kn, DPRINT 42 kn, SATCON (0230 UTC) 62 kn.

Jenna is now moving over cooler SSTs and is being affected by the ingestion of
dry air, the deep convection is confined to the southern quadrants and has
become less organised. Total Precipitable Water (TPW) shows drier air has moved
into the circulation, this combined with increasing north to northwest wind
shear should ensure rapid weakening continues. Gales are likely to persist
longer south of the centre during Thursday aided by its movement and the
broadscale forcing from the ridge to the south.  

Jenna is currently being steered towards the southwest by a mid-level ridge to
the east. This should continue in the short term then guidance shows good
agreement in the forecast becoming more westwards later Wednesday as the
steering becomes more shallow. Jenna is forecast to move west of 90E out of the
Australian Region during Thursday.  

Copyright Commonwealth of Australia
==
The next bulletin for this system will be issued by: 07/1330 UTC.

---

IDW24000
Australian Bureau of Meteorology
Tropical Cyclone Warning Centre

TROPICAL CYCLONE INFORMATION BULLETIN
Issued at 2:43 pm WST on Wednesday 7 January 2026

Tropical Cyclone Jenna (Category 2) was located at 2:00 pm AWST (12:30 pm CCT)
near 18.0S 92.4E,
that is 800 km southwest of Cocos (Keeling) Islands moving southwest at 17
kilometres per hour.

Tropical Cyclone Jenna (11U) is continuing to move southwest into the Indian
Ocean while it is weakening rapidly. The system is likely to decrease below
tropical cyclone strength during Thursday as it leaves the Australian Region.

The next Information Bulletin will be issued at 9:00 pm AWST Wednesday 07
January. .

	Time (AWST)	Intensity Category	Latitude (decimal deg.)	Longitude (decimal deg.)	Estimated Position Accuracy (km)
0hr	2 pm January 7	2	18.0S	92.4E	55
+6hr	8 pm January 7	2	18.2S	91.5E	80
+12hr	2 am January 8	1	18.3S	90.7E	95
+18hr	8 am January 8	tropical low	18.3S	90.0E	110
+24hr	2 pm January 8	tropical low	18.0S	89.1E	115
+36hr	2 am January 9	tropical low	17.6S	87.1E	130
+48hr	2 pm January 9	tropical low	XXX	XXX	XXX
+60hr	2 am January 10	tropical low	XXX	XXX	XXX
+72hr	2 pm January 10	tropical low	XXX	XXX	XXX

ygsj24

WTXS31 PGTW 070900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/TROPICAL CYCLONE 12S (JENNA) WARNING NR 006//
RMKS/
1. TROPICAL CYCLONE 12S (JENNA) WARNING NR 006   
   01 ACTIVE TROPICAL CYCLONE IN SOUTHIO
   MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE
   WIND RADII VALID OVER OPEN WATER ONLY
    ---
   WARNING POSITION:
   070600Z --- NEAR 18.0S 92.2E
     MOVEMENT PAST SIX HOURS - 230 DEGREES AT 10 KTS
     POSITION ACCURATE TO WITHIN 060 NM
     POSITION BASED ON CENTER LOCATED BY SATELLITE
   PRESENT WIND DISTRIBUTION:
   MAX SUSTAINED WINDS - 060 KT, GUSTS 075 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   RADIUS OF 050 KT WINDS - 040 NM NORTHEAST QUADRANT
                            055 NM SOUTHEAST QUADRANT
                            050 NM SOUTHWEST QUADRANT
                            040 NM NORTHWEST QUADRANT
   RADIUS OF 034 KT WINDS - 060 NM NORTHEAST QUADRANT
                            120 NM SOUTHEAST QUADRANT
                            090 NM SOUTHWEST QUADRANT
                            060 NM NORTHWEST QUADRANT
   REPEAT POSIT: 18.0S 92.2E
    ---
   FORECASTS:
   12 HRS, VALID AT:
   071800Z --- 18.6S 91.0E
   MAX SUSTAINED WINDS - 050 KT, GUSTS 065 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   RADIUS OF 050 KT WINDS - 020 NM NORTHEAST QUADRANT
                            050 NM SOUTHEAST QUADRANT
                            030 NM SOUTHWEST QUADRANT
                            020 NM NORTHWEST QUADRANT
   RADIUS OF 034 KT WINDS - 040 NM NORTHEAST QUADRANT
                            120 NM SOUTHEAST QUADRANT
                            090 NM SOUTHWEST QUADRANT
                            040 NM NORTHWEST QUADRANT
   VECTOR TO 24 HR POSIT: 270 DEG/ 07 KTS
    ---
   24 HRS, VALID AT:
   080600Z --- 18.6S 89.6E
   MAX SUSTAINED WINDS - 040 KT, GUSTS 050 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   RADIUS OF 034 KT WINDS - 020 NM NORTHEAST QUADRANT
                            090 NM SOUTHEAST QUADRANT
                            070 NM SOUTHWEST QUADRANT
                            030 NM NORTHWEST QUADRANT
   VECTOR TO 36 HR POSIT: 280 DEG/ 08 KTS
    ---
   36 HRS, VALID AT:
   081800Z --- 18.3S 88.0E
   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 - 000 NM NORTHEAST QUADRANT
                            070 NM SOUTHEAST QUADRANT
                            040 NM SOUTHWEST QUADRANT
                            000 NM NORTHWEST QUADRANT
   VECTOR TO 48 HR POSIT: 275 DEG/ 08 KTS
    ---
   EXTENDED OUTLOOK:
   48 HRS, VALID AT:
   090600Z --- 18.1S 86.3E
   MAX SUSTAINED WINDS - 030 KT, GUSTS 040 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   DISSIPATED AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER
    ---
REMARKS:
070900Z POSITION NEAR 18.2S 91.9E.
07JAN26. TROPICAL CYCLONE 12S (JENNA), LOCATED APPROXIMATELY 442
NM SOUTHWEST OF THE COCOS ISLANDS, HAS TRACKED SOUTHWESTWARD AT
10 KNOTS OVER THE PAST SIX HOURS.
MINIMUM CENTRAL PRESSURE AT 070600Z IS 990 MB.
MAXIMUM SIGNIFICANT WAVE HEIGHT AT 070600Z IS 25 FEET.
NEXT WARNINGS AT 072100Z AND 080900Z.//
NNNN

1. WDXS31 PGTW 070900
   
2. MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
   
3. SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 12S (JENNA) WARNING NR
   
4. 006//
   
5. RMKS/
   
6. 1. FOR METEOROLOGISTS.
   
7. 2. 6 HOUR SUMMARY AND ANALYSIS.
   
8. 
   
9. SUMMARY:
   
10.    INITIAL POSITION: 18.0S 92.2E
    
11.    INITIAL INTENSITY: 60 KTS
    
12.    GEOGRAPHIC REFERENCE: 442 NM SOUTHWEST OF THE COCOS ISLANDS
    
13.    MOVEMENT PAST 6 HOURS: SOUTHWESTWARD AT 10 KTS
    
14.    SIGNIFICANT WAVE HEIGHT: 25 FEET
    
15. 
    
16. SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
    
17. ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS TROPICAL
    
18. CYCLONE 12S (JENNA) WITH DEEP CONVECTION DRIFTING OFF TO THE SOUTH
    
19. OF THE LOW-LEVEL CIRCULATION CENTER (LLCC). THE SEPARATION OF THE
    
20. CONVECTION FROM THE CENTER OF THE SYSTEM HAS CAUSED THE NORTHERN
    
21. PORTION OF THE LLCC TO BECOME INCREASINGLY EXPOSED OVER THE PAST 6
    
22. HOURS. THE INITIAL POSITION IS PLACED WITH MEDIUM CONFIDENCE BASED
    
23. ON CLOUD TRACING IN THE ANIMATED MSI. THE INITIAL INTENSITY OF 60
    
24. KTS IS ASSESSED WITH MEDIUM CONFIDENCE BASED ON A BLEND OF THE
    
25. AGENCY DVORAK FIXES AND CIMSS OBJECTIVE INTENSITY ESTIMATES LISTED
    
26. BELOW. ENVIRONMENTAL ANALYSIS INDICATES THAT 12S IS NOW IN AN
    
27. UNFAVORABLE ENVIRONMENT CHARACTERIZED BY STRONG POLEWARD OUTFLOW
    
28. HEAVILY OFFSET BY MODERATE VERTICAL WIND SHEAR, SIGNIFICANT DRY AIR
    
29. ENTRAINMENT, AND MARGINAL (26-27 C) SEA SURFACE TEMPERATURES.
    
30. 
    
31. INITIAL WIND RADII BASIS: PERSISTENCE FROM THE 062309Z RCM-3 SAR
    
32. IMAGE WITH SLIGHT ADJUSTMENTS BASED ON THE OBJECTIVE BEST TRACK
    
33. 
    
34. CURRENT STEERING MECHANISM: WESTERN PERIPHERY OF A DEEP-LAYER
    
35. SUBTROPICAL RIDGE (STR) TO THE EAST
    
36. 
    
37. AGENCY DVORAK AND AUTOMATED FIXES:
    
38.    PGTW: T4.0 - 65 KTS
    
39.    DEMS: T4.0 - 65 KTS
    
40.    APRF: T4.0 - 65 KTS
    
41.    CIMSS SATCON: 54 KTS AT 070710Z
    
42.    CIMSS ADT: 65 KTS AT 070610Z
    
43.    CIMSS AIDT: 60 KTS AT 070610Z
    
44.    CIMSS D-PRINT: 46 KTS AT 070610Z
    
45. 
    
46. FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: UNFAVORABLE
    
47.    VWS: 15-20 KTS
    
48.    SST: 26-27 CELSIUS
    
49.    OUTFLOW: STRONG POLEWARD
    
50.    OTHER FACTORS: SIGNIFICANT DRY AIR ENTRAINMENT FROM THE WEST AND
    
51. NORTH
    
52. 
    
53. ANALYSIS CONFIDENCE:
    
54.    INITIAL POSITION: MEDIUM
    
55.    INITIAL INTENSITY: MEDIUM
    
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: TC 12S IS FORECAST TO TRACK SOUTHWESTWARD FOR
    
64. ONLY ANOTHER 12 HOURS OR SO BEFORE MAKING A WESTWARD TURN AS THE
    
65. STEERING MECHANISM SWITCHES TO A LOW TO MID-LEVEL RIDGE POSITIONED
    
66. TO THE SOUTHWEST. 12S IS THEN FORECAST TO TRACK GENERALLY WESTWARD,
    
67. ALONG THE NORTHERN PERIPHERY OF THE RIDGE THROUGH THE REMAINDER OF
    
68. THE FORECAST PERIOD. THE ENVIRONMENT IS EXPECTED TO ONLY WORSEN
    
69. WITH INCREASING NORTHWESTERLY VERTICAL WIND SHEAR DRY AIR
    
70. ENTRAINMENT, CAUSING 12S TO WEAKEN THROUGHOUT THE FORECAST PERIOD.
    
71. THE VORTEX IS EXPECTED TO COMPLETELY SHALLOW OUT AND DECOUPLE
    
72. WITHIN THE NEXT 24 HOURS AS DRY AIR ENGULFS THE SYSTEM. 12S IS
    
73. FORECAST TO DISSIPATE NEAR TAU 48 AS THE SYSTEM CONTINUES TO TRACK
    
74. OFF TO THE WEST.
    
75. 
    
76. MODEL DISCUSSION: NUMERICAL MODEL TRACK GUIDANCE IS IN GOOD
    
77. AGREEMENT THROUGHOUT THE FORECAST PERIOD WITH NO SIGNIFICANT
    
78. OUTLIERS. CROSS-TRACK SPREAD IS AROUND 80 NM AT TAU 48 WITH GALWEM
    
79. BEING THE NORTHERNMOST MEMBER WHILE ECMWF IS THE SOUTHERNMOST
    
80. MEMBER. THE JTWC TRACK FORECAST IS PLACED CLOSE TO THE MULTI-MODEL
    
81. CONSENSUS WITH HIGH CONFIDENCE. INTENSITY GUIDANCE AGREES ON
    
82. WEAKENING THROUGHOUT THE FORECAST PERIOD AND THE JTWC INTENSITY
    
83. FORECAST ALSO FOLLOWS THE CONSENSUS WITH HIGH CONFIDENCE.
    
84. 
    
85. FORECAST CONFIDENCE:
    
86.    TRACK 00-72 HR: HIGH
    
87.    INTENSITY 00-72 HR: HIGH//
    
88. NNNN

复制代码

pocketbox

全球热带气旋监测公报
预报：董议文、曹越男  签发：王海平  2026 年 01 月 07 日 18 时
“詹纳”向西南方向移动

时  间: 7日14时（北京时）

海  域: 澳大利亚附近海域

命  名: “詹纳”，JENNA

中心位置: 南纬18.0度，东经92.4度

强度等级: 二级热带气旋

最大风力: 10级，28米/秒，相当于我国的强热带风暴级

中心气压: 989百帕

参考位置: 距离科科斯群岛西南方向约800公里

变化过程: 过去24小时，“詹纳”强度由13级减弱为10级

预报结论: “詹纳”将以每小时17公里左右的速度向西南方向移动，强度逐渐减弱



图1  卫星红外监测图像（北京时间2026年1月7日14时00分）

pocketbox

IDW27600
TROPICAL CYCLONE TECHNICAL BULLETIN: AUSTRALIA - WESTERN REGION
Issued by AUSTRALIAN BUREAU OF METEOROLOGY TROPICAL CYCLONE WARNING CENTRE
at: 1253 UTC 07/01/2026
Name: Tropical Cyclone Jenna
Identifier: 11U
Data At: 1200 UTC
Latitude: 18.2S
Longitude: 91.8E
Location Accuracy: within 25nm (45 km)
Movement Towards: west southwest (251 deg)
Speed of Movement: 6 knots (11 km/h)
Maximum 10-Minute Wind: 45 knots (85 km/h)
Maximum 3-Second Wind Gust: 65 knots (120 km/h)
Central Pressure: 990 hPa
Radius of 34-knot winds NE quadrant: 50 nm (95 km)
Radius of 34-knot winds SE quadrant: 140 nm (260 km)
Radius of 34-knot winds SW quadrant: 140 nm (260 km)
Radius of 34-knot winds NW quadrant: 60 nm (110 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:   nm (  km)
Radius of Maximum Winds: 15 nm (30 km)
Dvorak Intensity Code: T3.0/3.5/W1.5/24HRS STT:W0.5/06HRS
Pressure of outermost isobar: 1006 hPa
Radius of outermost closed isobar: 100 nm (185 km)
FORECAST DATA
Date/Time    : Location    : Loc. Accuracy: Max Wind   : Central Pressure
(UTC)        : degrees     :      nm  (km): knots(km/h): hPa
+06:  07/1800: 18.3S  91.1E:     035 (070):  040  (075):  995
+12:  08/0000: 18.3S  90.6E:     045 (085):  035  (065):  995
+18:  08/0600: 18.1S  89.7E:     055 (100):  035  (065):  996
+24:  08/1200: 17.8S  88.8E:     060 (110):  035  (065):  997
+36:  09/0000: 17.7S  86.9E:     070 (130):  035  (065):  997
+48:  09/1200: 17.5S  84.8E:     080 (150):  030  (055): 1002
+60:  10/0000: 17.8S  83.0E:     100 (180):  025  (045): 1004
+72:  10/1200:             :              :            :     
+96:  11/1200:             :              :            :     
+120: 12/1200:             :              :            :     
REMARKS:
Tropical Cyclone Jenna (11U), now category 1, is weakening rapidly over the
open waters of the Indian Ocean.  

The location of Jenna was extrapolated from the 0752 UTC microwave pass after
the 0600 UTC analysis position was confirmed by the 0518 UTC scatterometry
pass, which gave a good fix. Locating the system using VIS/EIR imagery is
difficult now most of the deep convection has gone and there is no exposed  low
level centre.

Intensity is analysed at 45 kn based on Dvorak and objective guidance.

Dvorak analysis: DT=3.0 based on a shear pattern with LLC on edge of deep
convection. MET=3.0 based on a W+ 24-hour trend with -0.5 PAT adjustment to
2.5. FT/CI=3.0/3.5. Objective guidance at  1130 UTC (1-minute mean): CIMSS ADT
49 kn (FT/CI=2.7/3.2), AiDT 54 kn, DPRINT 43 kn, SATCON (1000 UTC) 53 kn.

Jenna is now moving over cooler SSTs and is being affected by the ingestion of
dry air, the deep convection is confined to the southern quadrants and has
become less organised. Total Precipitable Water (TPW) shows drier air has moved
into the circulation, this combined with increasing north to northwest wind
shear should ensure rapid weakening continues. Gales are likely to persist
longer south of the centre during Thursday and early Friday aided by its
movement and the broadscale forcing from the ridge to the south.  

Jenna has been steered towards the southwest by a mid-level ridge to the east,
which has eroded. Steering is becoming more shallow as the system weakens, and
the forecast westward movement is due to the mid-latitude ridge to the south.
Jenna is forecast to move west of 90E out of the Australian Region during
Thursday.  

Copyright Commonwealth of Australia
==
The next bulletin for this system will be issued by: 07/1930 UTC.

---

IDW24000
Australian Bureau of Meteorology
Tropical Cyclone Warning Centre

TROPICAL CYCLONE INFORMATION BULLETIN
Issued at 8:38 pm WST on Wednesday 7 January 2026

Tropical Cyclone Jenna (Category 1) was located at 8:00 pm AWST (6:30 pm CCT)
near 18.2S 91.8E,
that is 860 km southwest of Cocos (Keeling) Islands moving west southwest at 11
kilometres per hour.

Tropical Cyclone Jenna (11U) has been moving to the southwest, but is expected
to start moving to the west over the Indian Ocean tonight. Jenna has been
weakening rapidly, is now category 1 and is likely to decrease below tropical
cyclone strength during Thursday as it leaves the Australian Region.

The next Information Bulletin will be issued at 3:00 am AWST Thursday 08
January. .

	Time (AWST)	Intensity Category	Latitude (decimal deg.)	Longitude (decimal deg.)	Estimated Position Accuracy (km)
0hr	8 pm January 7	1	18.2S	91.8E	45
+6hr	2 am January 8	1	18.3S	91.1E	70
+12hr	8 am January 8	tropical low	18.3S	90.6E	85
+18hr	2 pm January 8	tropical low	18.1S	89.7E	100
+24hr	8 pm January 8	tropical low	17.8S	88.8E	110
+36hr	8 am January 9	tropical low	17.7S	86.9E	130
+48hr	8 pm January 9	tropical low	17.5S	84.8E	150
+60hr	8 am January 10	tropical low	17.8S	83.0E	180
+72hr	8 pm January 10	tropical low	XXX	XXX	XXX

ygsj24

IDW24000
Australian Bureau of Meteorology
Tropical Cyclone Warning Centre

TROPICAL CYCLONE INFORMATION BULLETIN
Issued at 2:27 am WST on Thursday 8 January 2026

Tropical Cyclone Jenna (Category 1) was located at 2:00 am AWST (12:30 am CCT)
near 18.3S 91.2E,
that is 910 km southwest of Cocos (Keeling) Islands moving west at 11
kilometres per hour.

Tropical Cyclone Jenna (11U) is forecast to move west over the Indian Ocean.
Jenna has been weakening rapidly, and is likely to decrease below tropical
cyclone strength during Thursday morning as it leaves the Australian Region.

The next Information Bulletin will be issued at 9:00 am AWST Thursday 08
January. .

	Time (AWST)	Intensity Category	Latitude (decimal deg.)	Longitude (decimal deg.)	Estimated Position Accuracy (km)
0hr	2 am January 8	1	18.3S	91.2E	55
+6hr	8 am January 8	tropical low	18.3S	90.7E	80
+12hr	2 pm January 8	tropical low	18.1S	89.9E	95
+18hr	8 pm January 8	tropical low	17.9S	89.0E	110
+24hr	2 am January 9	tropical low	17.8S	88.0E	115
+36hr	2 pm January 9	tropical low	17.6S	86.0E	130
+48hr	2 am January 10	tropical low	17.6S	84.1E	135
+60hr	2 pm January 10	tropical low	XXX	XXX	XXX
+72hr	2 am January 11	tropical low	XXX	XXX	XXX

1. AXAU01 APRF 071833
   
2. IDW27600
   
3. TROPICAL CYCLONE TECHNICAL BULLETIN: AUSTRALIA - WESTERN REGION
   
4. ISSUED BY AUSTRALIAN BUREAU OF METEOROLOGY TROPICAL CYCLONE WARNING CENTRE
   
5. AT: 1833 UTC 07/01/2026
   
6. NAME: TROPICAL CYCLONE JENNA
   
7. IDENTIFIER: 11U
   
8. DATA AT: 1800 UTC
   
9. LATITUDE: 18.3S
   
10. LONGITUDE: 91.2E
    
11. LOCATION ACCURACY: WITHIN 30NM (55 KM)
    
12. MOVEMENT TOWARDS: WEST (260 DEG)
    
13. SPEED OF MOVEMENT: 6 KNOTS (11 KM/H)
    
14. MAXIMUM 10-MINUTE WIND: 40 KNOTS (75 KM/H)
    
15. MAXIMUM 3-SECOND WIND GUST: 55 KNOTS (100 KM/H)
    
16. CENTRAL PRESSURE: 997 HPA
    
17. RADIUS OF 34-KNOT WINDS NE QUADRANT: 50 NM (95 KM)
    
18. RADIUS OF 34-KNOT WINDS SE QUADRANT: 140 NM (260 KM)
    
19. RADIUS OF 34-KNOT WINDS SW QUADRANT: 140 NM (260 KM)
    
20. RADIUS OF 34-KNOT WINDS NW QUADRANT: 60 NM (110 KM)
    
21. RADIUS OF 48-KNOT WINDS NE QUADRANT:
    
22. RADIUS OF 48-KNOT WINDS SE QUADRANT:
    
23. RADIUS OF 48-KNOT WINDS SW QUADRANT:
    
24. RADIUS OF 48-KNOT WINDS NW QUADRANT:
    
25. RADIUS OF 64-KNOT WINDS:   NM (  KM)
    
26. RADIUS OF MAXIMUM WINDS: 15 NM (30 KM)
    
27. DVORAK INTENSITY CODE: T2.5/3.0/W1.5/24HRS STT:W0.5/06HRS
    
28. PRESSURE OF OUTERMOST ISOBAR: 1008 HPA
    
29. RADIUS OF OUTERMOST CLOSED ISOBAR: 110 NM (205 KM)
    
30. FORECAST DATA
    
31. DATE/TIME    : LOCATION    : LOC. ACCURACY: MAX WIND   : CENTRAL PRESSURE
    
32. (UTC)        : DEGREES     :      NM  (KM): KNOTS(KM/H): HPA
    
33. +06:  08/0000: 18.3S  90.7E:     040 (080):  035  (065):  997
    
34. +12:  08/0600: 18.1S  89.9E:     050 (095):  035  (065):  997
    
35. +18:  08/1200: 17.9S  89.0E:     060 (110):  035  (065):  999
    
36. +24:  08/1800: 17.8S  88.0E:     065 (115):  035  (065):  999
    
37. +36:  09/0600: 17.6S  86.0E:     070 (130):  030  (055): 1004
    
38. +48:  09/1800: 17.6S  84.1E:     075 (135):  030  (055): 1003
    
39. +60:  10/0600:             :              :            :
    
40. +72:  10/1800:             :              :            :
    
41. +96:  11/1800:             :              :            :
    
42. +120: 12/1800:             :              :            :
    
43. REMARKS:
    
44. TROPICAL CYCLONE JENNA (11U) HAS BEEN WEAKENING RAPIDLY OVER THE OPEN WATERS OF
    
45. THE INDIAN OCEAN.
    
46. 
    
47. THE LOCATION OF JENNA WAS EXTRAPOLATED FROM THE 1206 UTC MICROWAVE PASS AND THE
    
48. FORECAST, WITH ONLY A FAIR FIX. LOCATING THE SYSTEM USING VIS/EIR IMAGERY IS
    
49. DIFFICULT NOW MOST OF THE DEEP CONVECTION HAS GONE AND THERE IS NO EXPOSED  LOW
    
50. LEVEL CENTRE.
    
51. 
    
52. INTENSITY IS ANALYSED AT 40 KN BASED ON DVORAK AND OBJECTIVE GUIDANCE.
    
53. 
    
54. DVORAK ANALYSIS: DT=3.0 BASED ON A SHEAR PATTERN WITH LLC JUST OUTSIDE THE EDGE
    
55. OF DEEP CONVECTION, HOWEVER MORE WEIGHT GIVEN TO MET AND PAT. MET=2.5 BASED ON
    
56. A W+ 24-HOUR TREND WITH NO ADJUSTMENT TO PAT. FT/CI=2.5/3.0. OBJECTIVE GUIDANCE
    
57. AT  1730 UTC (1-MINUTE MEAN): CIMSS ADT 37 KN (FT/CI=2.1/2.6), AIDT 49 KN,
    
58. DPRINT 37 KN, SATCON (1000 UTC) 53 KN.
    
59. 
    
60. JENNA IS NOW MOVING OVER COOLER SSTS OF ABOUT 26 DEGREES, AND IS BEING AFFECTED
    
61. BY THE INGESTION OF DRY AIR, THE DEEP CONVECTION IS CONFINED TO THE SOUTHERN
    
62. QUADRANTS AND HAS BECOME LESS ORGANISED. TOTAL PRECIPITABLE WATER (TPW) SHOWS
    
63. DRIER AIR HAS MOVED INTO THE CIRCULATION, THIS COMBINED WITH INCREASING NORTH
    
64. TO NORTHWEST WIND SHEAR SHOULD ENSURE WEAKENING CONTINUES. GALES ARE LIKELY TO
    
65. PERSIST LONGER SOUTH OF THE CENTRE DURING THURSDAY AND EARLY FRIDAY AIDED BY
    
66. ITS MOVEMENT AND THE BROADSCALE FORCING FROM THE RIDGE TO THE SOUTH. SOUTHERN
    
67. GALE RADII WERE INCREASED ON THE PREVIOUS ISSUE BASED ON EARLY SCATTEROMETRY
    
68. PASSES.
    
69. 
    
70. JENNA HAS BEEN STEERED TOWARDS THE SOUTHWEST BY A MID-LEVEL RIDGE TO THE EAST,
    
71. WHICH HAS ERODED. STEERING IS BECOMING MORE SHALLOW AS THE SYSTEM WEAKENS, AND
    
72. THE FORECAST WESTWARD MOVEMENT IS DUE TO THE MID-LATITUDE RIDGE TO THE SOUTH.
    
73. JENNA IS FORECAST TO MOVE WEST OF 90E OUT OF THE AUSTRALIAN REGION DURING
    
74. THURSDAY.
    
75. 
    
76. COPYRIGHT COMMONWEALTH OF AUSTRALIA
    
77. ==
    
78. THE NEXT BULLETIN FOR THIS SYSTEM WILL BE ISSUED BY: 08/0130 UTC.=

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ygsj24

WTXS31 PGTW 072100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/TROPICAL CYCLONE 12S (JENNA) WARNING NR 007//
RMKS/
1. TROPICAL CYCLONE 12S (JENNA) 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:
   071800Z --- NEAR 18.6S 91.2E
     MOVEMENT PAST SIX HOURS - 240 DEGREES AT 06 KTS
     POSITION ACCURATE TO WITHIN 060 NM
     POSITION BASED ON CENTER LOCATED BY SATELLITE
   PRESENT WIND DISTRIBUTION:
   MAX SUSTAINED WINDS - 050 KT, GUSTS 065 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   RADIUS OF 050 KT WINDS - 000 NM NORTHEAST QUADRANT
                            090 NM SOUTHEAST QUADRANT
                            085 NM SOUTHWEST QUADRANT
                            030 NM NORTHWEST QUADRANT
   RADIUS OF 034 KT WINDS - 060 NM NORTHEAST QUADRANT
                            180 NM SOUTHEAST QUADRANT
                            165 NM SOUTHWEST QUADRANT
                            045 NM NORTHWEST QUADRANT
   REPEAT POSIT: 18.6S 91.2E
    ---
   FORECASTS:
   12 HRS, VALID AT:
   080600Z --- 18.5S 89.9E
   MAX SUSTAINED WINDS - 040 KT, GUSTS 050 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   RADIUS OF 034 KT WINDS - 010 NM NORTHEAST QUADRANT
                            120 NM SOUTHEAST QUADRANT
                            100 NM SOUTHWEST QUADRANT
                            010 NM NORTHWEST QUADRANT
   VECTOR TO 24 HR POSIT: 275 DEG/ 09 KTS
    ---
   24 HRS, VALID AT:
   081800Z --- 18.3S 88.1E
   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 - 000 NM NORTHEAST QUADRANT
                            090 NM SOUTHEAST QUADRANT
                            070 NM SOUTHWEST QUADRANT
                            000 NM NORTHWEST QUADRANT
   VECTOR TO 36 HR POSIT: 275 DEG/ 10 KTS
    ---
   36 HRS, VALID AT:
   090600Z --- 18.1S 86.1E
   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 - 010 NM NORTHEAST QUADRANT
                            090 NM SOUTHEAST QUADRANT
                            080 NM SOUTHWEST QUADRANT
                            000 NM NORTHWEST QUADRANT
   VECTOR TO 48 HR POSIT: 265 DEG/ 10 KTS
    ---
   EXTENDED OUTLOOK:
   48 HRS, VALID AT:
   091800Z --- 18.2S 84.1E
   MAX SUSTAINED WINDS - 030 KT, GUSTS 040 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   DISSIPATED AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER
    ---
REMARKS:
072100Z POSITION NEAR 18.6S 90.9E.
07JAN26. TROPICAL CYCLONE 12S (JENNA), LOCATED APPROXIMATELY 506
NM SOUTHWEST OF THE COCOS ISLANDS, HAS TRACKED WEST-SOUTHWESTWARD
AT 06 KNOTS OVER THE PAST SIX HOURS. MINIMUM CENTRAL PRESSURE AT
071800Z IS 993 MB. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 071800Z IS 23
FEET. NEXT WARNINGS AT 080900Z AND 082100Z.//
NNNN

1. WDXS31 PGTW 072100
   
2. MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
   
3. SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 12S (JENNA) WARNING NR
   
4. 007//
   
5. RMKS/
   
6. 1. FOR METEOROLOGISTS.
   
7. 2. 6 HOUR SUMMARY AND ANALYSIS.
   
8. 
   
9. SUMMARY:
   
10.    INITIAL POSITION: 18.6S 91.2E
    
11.    INITIAL INTENSITY: 50 KTS
    
12.    GEOGRAPHIC REFERENCE: 506 NM SOUTHWEST OF THE COCOS ISLANDS
    
13.    MOVEMENT PAST 6 HOURS: WEST-SOUTHWESTWARD AT 06 KTS
    
14.    SIGNIFICANT WAVE HEIGHT: 23 FEET
    
15. 
    
16. SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
    
17. ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS A
    
18. DECAYING VORTEX COMPLETING A DECOUPLING PROCESS DUE TO WESTERLY
    
19. VERTICAL SHEAR OF AROUND 30 KT, PUSHING ANY REMAINING DEEP
    
20. CONVECTION WELL TO THE SOUTHEAST OF THE LOW-LEVEL CIRCULATION
    
21. CENTER (LLCC). A DEEP-LAYER DRY AIR MASS IS NOW OVERSPREADING THE
    
22. LLCC FROM THE WEST AND NORTH. AN EARLIER 171133Z SMOS PASS
    
23. INDICATED THAT THE STORM RETAINS A STRONG WIND FIELD, WITH MAXIMUM
    
24. WINDS OF AROUND 55 KT SOUTH OF THE LLCC AT THE TIME. THE INITIAL
    
25. INTENSITY IS SET AT 50 KT, ASSUMING GRADUAL SPIN-DOWN OF THE WIND
    
26. FIELD HAS CONTINUED OVER THE PAST SIX HOURS. THE LACK OF DEEP
    
27. CONVECTION IS LEADING TRADITIONAL DVORAK ESTIMATES TO RUN A BIT
    
28. LOWER.
    
29. 
    
30. INITIAL WIND RADII BASIS: SMOS DATA
    
31. 
    
32. CURRENT STEERING MECHANISM: LOW-LEVEL SUBTROPICAL RIDGE TO THE
    
33. SOUTH
    
34. 
    
35. AGENCY DVORAK AND AUTOMATED FIXES:
    
36.    PGTW: T3.0 - 45 KTS
    
37.    CIMSS AIDT: 51 KTS AT 071420Z
    
38.    CIMSS D-PRINT: 36 KTS AT 071720Z
    
39. 
    
40. FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: HIGHLY UNFAVORABLE
    
41.    VWS: 30+ KTS
    
42.    SST: 26-27 CELSIUS
    
43.    OUTFLOW: WEAK POLEWARD
    
44.    OTHER FACTORS: DEEP-LAYER DRY AIR MASS OVERSPREADING THE LLCC
    
45. FROM THE WEST AND NORTH
    
46. 
    
47. ANALYSIS CONFIDENCE:
    
48.    INITIAL POSITION: MEDIUM
    
49.    INITIAL INTENSITY: MEDIUM
    
50.    INITIAL WIND RADII: HIGH
    
51. 
    
52. 3. FORECAST REASONING.
    
53. 
    
54. SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO
    
55. THE FORECAST FROM THE PREVIOUS WARNING.
    
56. 
    
57. FORECAST DISCUSSION: TROPICAL CYCLONE 12S (JENNA) HAS NOW BEEN
    
58. DECOUPLED BY STRONG WESTERLY SHEAR, AND THE SHALLOW SURFACE VORTEX
    
59. IS NOW TURNING WESTWARD ALONG THE NORTHERN PERIPHERY OF THE
    
60. SUBTROPICAL RIDGE. WESTERLY SHEAR OF AT LEAST 30 KT IS EXPECTED TO
    
61. PERSIST OVER THE NEXT COUPLE OF DAYS AS AN ANTICYCLONIC
    
62. WAVEBREAKING EVENT OVER THE SOUTHWESTERN INDIAN OCEAN DRIVES
    
63. UPPER-LEVEL WESTERLIES EQUATORWARD, AS FAR AS THE 15-20S LATITUDE
    
64. BELT. THIS SHEAR WILL FORCE CONTINUED DECAY OF THE VORTEX AS IT
    
65. TRANSITS WESTWARD THROUGH A DEEP-LAYER DRY AIR MASS. THE INTENSITY
    
66. FORECAST IS BASED ON GRADUAL SPIN-DOWN OF THE WIND FIELD, WITH
    
67. GALES POSSIBLY LINGERING FOR AS LONG AS 36 HOURS DUE TO ENHANCED
    
68. GRADIENT FLOW IN THE SOUTHERN SEMICIRCLE OF THE STORM. THE JTWC
    
69. FORECAST TERMINATES AT 48 HOURS WHEN JENNA IS FORECAST TO DECAY
    
70. BELOW THE WARNING THRESHOLD OF 35 KT.
    
71. 
    
72. MODEL DISCUSSION: THE JTWC TRACK FORECAST IS CLOSE TO THE
    
73. MULTI-MODEL CONSENSUS, AND THE JTWC INTENSITY FORECAST IS CLOSE TO
    
74. A BLEND OF THE GFS AND ECMWF GLOBAL MODELS.
    
75. 
    
76. FORECAST CONFIDENCE:
    
77.    TRACK 00-72 HR: HIGH
    
78.    INTENSITY 00-72 HR: HIGH//
    
79. NNNN

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ygsj24

IDW24000
Australian Bureau of Meteorology
Tropical Cyclone Warning Centre

TROPICAL CYCLONE INFORMATION BULLETIN
Issued at 9:07 am WST on Thursday 8 January 2026

Ex-Tropical Cyclone Jenna was located at 8:00 am AWST (6:30 am CCT) near 18.4S
90.9E,
that is 940 km southwest of Cocos (Keeling) Islands moving west southwest at 10
kilometres per hour.

Ex-tropical cyclone Jenna (11U) is weakening as it moves west southwest over
the Indian Ocean. It is likely to move west of the Australian Region (90E)
today. Gales will persist southwest of the centre

No further Information Bulletins will be issued.

	Time (AWST)	Intensity Category	Latitude (decimal deg.)	Longitude (decimal deg.)	Estimated Position Accuracy (km)
0hr	8 am January 8	tropical low	18.4S	90.9E	35
+6hr	2 pm January 8	tropical low	18.5S	90.1E	60
+12hr	8 pm January 8	tropical low	18.3S	89.2E	75
+18hr	2 am January 9	tropical low	18.2S	88.2E	90
+24hr	8 am January 9	tropical low	18.1S	87.2E	100
+36hr	8 pm January 9	tropical low	XXX	XXX	XXX
+48hr	8 am January 10	tropical low	XXX	XXX	XXX
+60hr	8 pm January 10	tropical low	XXX	XXX	XXX
+72hr	8 am January 11	tropical low	XXX	XXX	XXX

1. AXAU01 APRF 080106
   
2. IDW27600
   
3. TROPICAL CYCLONE TECHNICAL BULLETIN: AUSTRALIA - WESTERN REGION
   
4. ISSUED BY AUSTRALIAN BUREAU OF METEOROLOGY TROPICAL CYCLONE WARNING CENTRE
   
5. AT: 0105 UTC 08/01/2026
   
6. NAME: EX-TROPICAL CYCLONE JENNA
   
7. IDENTIFIER: 11U
   
8. DATA AT: 0000 UTC
   
9. LATITUDE: 18.4S
   
10. LONGITUDE: 90.9E
    
11. LOCATION ACCURACY: WITHIN 20NM (35 KM)
    
12. MOVEMENT TOWARDS: WEST SOUTHWEST (257 DEG)
    
13. SPEED OF MOVEMENT: 6 KNOTS (10 KM/H)
    
14. MAXIMUM 10-MINUTE WIND: 40 KNOTS (75 KM/H)
    
15. MAXIMUM 3-SECOND WIND GUST: 55 KNOTS (100 KM/H)
    
16. CENTRAL PRESSURE: 995 HPA
    
17. RADIUS OF 34-KNOT WINDS NE QUADRANT:
    
18. RADIUS OF 34-KNOT WINDS SE QUADRANT: 120 NM (220 KM)
    
19. RADIUS OF 34-KNOT WINDS SW QUADRANT: 120 NM (220 KM)
    
20. RADIUS OF 34-KNOT WINDS NW QUADRANT:
    
21. RADIUS OF 48-KNOT WINDS NE QUADRANT:
    
22. RADIUS OF 48-KNOT WINDS SE QUADRANT:
    
23. RADIUS OF 48-KNOT WINDS SW QUADRANT:
    
24. RADIUS OF 48-KNOT WINDS NW QUADRANT:
    
25. RADIUS OF 64-KNOT WINDS:   NM (  KM)
    
26. RADIUS OF MAXIMUM WINDS:   NM (  KM)
    
27. DVORAK INTENSITY CODE: T1.5/2.0/W2.5/24HRS STT:W0.5/06HRS
    
28. PRESSURE OF OUTERMOST ISOBAR: 1008 HPA
    
29. RADIUS OF OUTERMOST CLOSED ISOBAR: 130 NM (240 KM)
    
30. FORECAST DATA
    
31. DATE/TIME    : LOCATION    : LOC. ACCURACY: MAX WIND   : CENTRAL PRESSURE
    
32. (UTC)        : DEGREES     :      NM  (KM): KNOTS(KM/H): HPA
    
33. +06:  08/0600: 18.5S  90.1E:     030 (060):  040  (075):  996
    
34. +12:  08/1200: 18.3S  89.2E:     040 (075):  035  (065):  999
    
35. +18:  08/1800: 18.2S  88.2E:     050 (090):  035  (065): 1000
    
36. +24:  09/0000: 18.1S  87.2E:     055 (100):  030  (055): 1005
    
37. +36:  09/1200:             :              :            :
    
38. +48:  10/0000:             :              :            :
    
39. +60:  10/1200:             :              :            :
    
40. +72:  11/0000:             :              :            :
    
41. +96:  12/0000:             :              :            :
    
42. +120: 13/0000:             :              :            :
    
43. REMARKS:
    
44. EX-TROPICAL CYCLONE JENNA (11U) CONTINUES TO WEAKEN OVER OPEN WATERS OF THE
    
45. INDIAN OCEAN.
    
46. VISIBLE IMAGERY SHOWS THE EXPOSED CENTRE OF JENNA AND WITHOUT ANY DEEP
    
47. CONVECTION NEAR THE CENTRE. OSCAT AT 1735UTC SUPPORTED BY AMSR2 WINDS AT
    
48. 1845UTC SHOWED GALES ONLY TO THE SOUTH OF THE CENTRE
    
49. 
    
50. INTENSITY IS ANALYSED AT 40 KN BASED ON EARLIER SCATTEROMETRY SUPPORTED BY
    
51. MODEL GUIDANCE.
    
52. DVORAK ANALYSIS: NO DT GIVEN LACK OF DEEP CONVECTION. MET=2.0 BASED ON A W+
    
53. 24-HOUR TREND WITH   0.5 PAT ADJUSTMENT. FT/CI=1.5/2.0. OBJECTIVE GUIDANCE AT
    
54. 0000 UTC (1-MINUTE MEAN): ADT 33 KN (FT/CI=1.5/2.3), AIDT 35 KN, DPRINT 33 KN,
    
55. SATCON (2100 UTC) 43 KN.
    
56. THE CIRCULATION LACKS ACCESS TO MOISTURE AND NOW OVER  COOLER SSTS OF ABOUT 26
    
57. DEGREES. MODEL GUIDANCE INDICATES CONTINUING GALES SOUTHWEST OF THE CENTRE FOR
    
58. ABOUT 24 H ASSISTED BY THE MODTION AND SYNOPTIC FORCING FROM THE RIDGE TO THE
    
59. SOUTH. STEERING IS BECOMING MORE SHALLOW AS THE SYSTEM WEAKENS, AND THE
    
60. FORECAST WESTWARD MOVEMENT IS DUE TO THE MID-LATITUDE RIDGE TO THE SOUTH.
    
61. 
    
62. THE SYSTEM IS FORECAST TO MOVE WEST OF 90E OUT OF THE AUSTRALIAN REGION LATE
    
63. THURSDAY.
    
64. 
    
65. COPYRIGHT COMMONWEALTH OF AUSTRALIA
    
66. ==
    
67. THE NEXT BULLETIN FOR THIS SYSTEM WILL BE ISSUED BY: 08/0730 UTC.=

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