09S.Grant 環流小巧快速增強風眼開啟升格強烈熱帶氣旋

king111807 · 2026-1-1 16:41

JTWC降格C1

WTXS32 PGTW 010300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/TROPICAL CYCLONE 09S (GRANT) WARNING NR 030//
RMKS/
1. TROPICAL CYCLONE 09S (GRANT) WARNING NR 030
02 ACTIVE TROPICAL CYCLONES IN SOUTHIO
MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE
WIND RADII VALID OVER OPEN WATER ONLY
---
WARNING POSITION:
010000Z --- NEAR 16.2S 69.1E
   MOVEMENT PAST SIX HOURS - 255 DEGREES AT 09 KTS
   POSITION ACCURATE TO WITHIN 060 NM
   POSITION BASED ON CENTER LOCATED BY SATELLITE
PRESENT WIND DISTRIBUTION:
MAX SUSTAINED WINDS - 070 KT, GUSTS 085 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
                        020 NM NORTHWEST QUADRANT
RADIUS OF 050 KT WINDS - 030 NM NORTHEAST QUADRANT
                        030 NM SOUTHEAST QUADRANT
                        030 NM SOUTHWEST QUADRANT
                        030 NM NORTHWEST QUADRANT
RADIUS OF 034 KT WINDS - 050 NM NORTHEAST QUADRANT
                        060 NM SOUTHEAST QUADRANT
                        060 NM SOUTHWEST QUADRANT
                        050 NM NORTHWEST QUADRANT
REPEAT POSIT: 16.2S 69.1E
---
FORECASTS:
12 HRS, VALID AT:
011200Z --- 16.3S 68.1E
MAX SUSTAINED WINDS - 055 KT, GUSTS 070 KT
WIND RADII VALID OVER OPEN WATER ONLY
RADIUS OF 050 KT WINDS - 020 NM NORTHEAST QUADRANT
                        020 NM SOUTHEAST QUADRANT
                        020 NM SOUTHWEST QUADRANT
                        020 NM NORTHWEST QUADRANT
RADIUS OF 034 KT WINDS - 040 NM NORTHEAST QUADRANT
                        050 NM SOUTHEAST QUADRANT
                        050 NM SOUTHWEST QUADRANT
                        050 NM NORTHWEST QUADRANT
VECTOR TO 24 HR POSIT: 290 DEG/ 04 KTS
---
24 HRS, VALID AT:
020000Z --- 16.0S 67.3E
MAX SUSTAINED WINDS - 050 KT, GUSTS 065 KT
WIND RADII VALID OVER OPEN WATER ONLY
RADIUS OF 050 KT WINDS - 020 NM NORTHEAST QUADRANT
                        020 NM SOUTHEAST QUADRANT
                        020 NM SOUTHWEST QUADRANT
                        020 NM NORTHWEST QUADRANT
RADIUS OF 034 KT WINDS - 040 NM NORTHEAST QUADRANT
                        050 NM SOUTHEAST QUADRANT
                        050 NM SOUTHWEST QUADRANT
                        050 NM NORTHWEST QUADRANT
VECTOR TO 36 HR POSIT: 285 DEG/ 04 KTS
---
36 HRS, VALID AT:
021200Z --- 15.8S 66.4E
MAX SUSTAINED WINDS - 045 KT, GUSTS 055 KT
WIND RADII VALID OVER OPEN WATER ONLY
RADIUS OF 034 KT WINDS - 030 NM NORTHEAST QUADRANT
                        050 NM SOUTHEAST QUADRANT
                        050 NM SOUTHWEST QUADRANT
                        040 NM NORTHWEST QUADRANT
VECTOR TO 48 HR POSIT: 280 DEG/ 07 KTS
---
EXTENDED OUTLOOK:
48 HRS, VALID AT:
030000Z --- 15.6S 65.0E
MAX SUSTAINED WINDS - 045 KT, GUSTS 055 KT
WIND RADII VALID OVER OPEN WATER ONLY
RADIUS OF 034 KT WINDS - 030 NM NORTHEAST QUADRANT
                        050 NM SOUTHEAST QUADRANT
                        040 NM SOUTHWEST QUADRANT
                        030 NM NORTHWEST QUADRANT
VECTOR TO 72 HR POSIT: 265 DEG/ 09 KTS
---
72 HRS, VALID AT:
040000Z --- 16.0S 61.4E
MAX SUSTAINED WINDS - 050 KT, GUSTS 065 KT
WIND RADII VALID OVER OPEN WATER ONLY
RADIUS OF 050 KT WINDS - 020 NM NORTHEAST QUADRANT
                        020 NM SOUTHEAST QUADRANT
                        020 NM SOUTHWEST QUADRANT
                        000 NM NORTHWEST QUADRANT
RADIUS OF 034 KT WINDS - 030 NM NORTHEAST QUADRANT
                        050 NM SOUTHEAST QUADRANT
                        040 NM SOUTHWEST QUADRANT
                        030 NM NORTHWEST QUADRANT
VECTOR TO 96 HR POSIT: 260 DEG/ 10 KTS
---
LONG RANGE OUTLOOK:
---
96 HRS, VALID AT:
050000Z --- 16.7S 57.1E
MAX SUSTAINED WINDS - 060 KT, GUSTS 075 KT
WIND RADII VALID OVER OPEN WATER ONLY
RADIUS OF 050 KT WINDS - 030 NM NORTHEAST QUADRANT
                        030 NM SOUTHEAST QUADRANT
                        020 NM SOUTHWEST QUADRANT
                        020 NM NORTHWEST QUADRANT
RADIUS OF 034 KT WINDS - 050 NM NORTHEAST QUADRANT
                        060 NM SOUTHEAST QUADRANT
                        060 NM SOUTHWEST QUADRANT
                        050 NM NORTHWEST QUADRANT
VECTOR TO 120 HR POSIT: 255 DEG/ 09 KTS
---
120 HRS, VALID AT:
060000Z --- 17.5S 53.5E
MAX SUSTAINED WINDS - 070 KT, GUSTS 085 KT
WIND RADII VALID OVER OPEN WATER ONLY
RADIUS OF 064 KT WINDS - 020 NM NORTHEAST QUADRANT
                        030 NM SOUTHEAST QUADRANT
                        020 NM SOUTHWEST QUADRANT
                        020 NM NORTHWEST QUADRANT
RADIUS OF 050 KT WINDS - 030 NM NORTHEAST QUADRANT
                        040 NM SOUTHEAST QUADRANT
                        040 NM SOUTHWEST QUADRANT
                        030 NM NORTHWEST QUADRANT
RADIUS OF 034 KT WINDS - 060 NM NORTHEAST QUADRANT
                        080 NM SOUTHEAST QUADRANT
                        070 NM SOUTHWEST QUADRANT
                        060 NM NORTHWEST QUADRANT
---
REMARKS:
010300Z POSITION NEAR 16.2S 68.8E.
01JAN26. TROPICAL CYCLONE 09S (GRANT), LOCATED APPROXIMATELY 581
NM SOUTH-SOUTHWEST OF DIEGO GARCIA, HAS TRACKED WEST-
SOUTHWESTWARD AT 09 KNOTS OVER THE PAST SIX HOURS.
MINIMUM CENTRAL PRESSURE AT 010000Z IS 984 MB. MAXIMUM
SIGNIFICANT WAVE HEIGHT AT 010000Z IS 24 FEET.
NEXT WARNINGS AT 011500Z AND 020300Z.
REFER TO TROPICAL CYCLONE 11S (ELEVEN) WARNINGS (WTXS31 PGTW)
FOR SIX-HOURLY UPDATES.//
NNNN

king111807 · 2026-1-1 17:16

MFR降格熱帶氣旋

WTIO30 FMEE 311313 CCA
***************CORRECTIVE**************
RSMC / TROPICAL CYCLONE CENTER / LA REUNION
TROPICAL CYCLONE FORECAST WARNING (SOUTH-WEST INDIAN OCEAN)

0.A WARNING NUMBER: 18/5/20252026
1.A TROPICAL CYCLONE 5 (GRANT)

2.A POSITION 2025/12/31 AT 1200 UTC:
WITHIN 30 NM RADIUS OF POINT 16.0 S / 70.9 E
(SIXTEEN DECIMAL ZERO DEGREES SOUTH AND
SEVENTY DECIMAL NINE DEGREES EAST)
MOVEMENT: WEST-SOUTH-WEST 11 KT

3.A DVORAK ANALYSIS: 4.5/5.0/W 0.5/6 H

4.A CENTRAL PRESSURE: 971 HPA
5.A MAX AVERAGE WIND SPEED (10 MN): 85 KT
RADIUS OF MAXIMUM WINDS (RMW): 19 KM

6.A EXTENSION OF WIND BY QUADRANTS (KM):
28 KT NE: 100 SE: 95 SW: 95 NW: 110
34 KT NE: 75 SE: 55 SW: 45 NW: 65
48 KT NE: 35 SE: 35 SW: 40 NW: 35
64 KT NE: 30 SE: 30 SW: 30 NW: 30

7.A FIRST CLOSED ISOBAR (PRESSURE / AVERAGE DIAM): 1009 HPA / 500 KM
8.A VERTICAL EXTENSION OF CYCLONE CIRCULATION: DEEP

1.B FORECASTS (WINDS RADII IN KM):
12H: 2026/01/01 00 UTC: 16.5 S / 69.2 E, VENT MAX= 075 KT, TROPICAL
CYCLONE
28 KT NE: 130 SE: 130 SW: 140 NW: 130
34 KT NE: 85 SE: 85 SW: 85 NW: 75
48 KT NE: 55 SE: 45 SW: 65 NW: 45
64 KT NE: 45 SE: 35 SW: 35 NW: 35

24H: 2026/01/01 12 UTC: 16.2 S / 67.8 E, VENT MAX= 055 KT, SEVERE
TROPICAL STORM
28 KT NE: 130 SE: 130 SW: 150 NW: 130
34 KT NE: 85 SE: 75 SW: 75 NW: 85
48 KT NE: 55 SE: 55 SW: 55 NW: 45

36H: 2026/01/02 00 UTC: 15.8 S / 66.8 E, VENT MAX= 045 KT, MODERATE
TROPICAL STORM
28 KT NE: 130 SE: 150 SW: 130 NW: 140
34 KT NE: 85 SE: 85 SW: 0 NW: 85

48H: 2026/01/02 12 UTC: 15.4 S / 65.7 E, VENT MAX= 040 KT, MODERATE
TROPICAL STORM
28 KT NE: 110 SE: 150 SW: 130 NW: 120
34 KT NE: 75 SE: 75 SW: 0 NW: 75

60H: 2026/01/03 00 UTC: 15.2 S / 64.4 E, VENT MAX= 035 KT, MODERATE
TROPICAL STORM
28 KT NE: 120 SE: 155 SW: 120 NW: 120
34 KT NE: 85 SE: 75 SW: 0 NW: 75

72H: 2026/01/03 12 UTC: 15.2 S / 63.0 E, VENT MAX= 030 KT, TROPICAL
DEPRESSION
28 KT NE: 120 SE: 205 SW: 150 NW: 110

2.B LONGER-RANGE OUTLOOK:
96H: 2026/01/04 12 UTC: 15.7 S / 59.4 E, VENT MAX= 030 KT, TROPICAL
DEPRESSION
28 KT NE: 120 SE: 185 SW: 120 NW: 110

120H: 2026/01/05 12 UTC: 16.4 S / 55.5 E, VENT MAX= 030 KT, TROPICAL
DEPRESSION
28 KT NE: 140 SE: 230 SW: 150 NW: 130

2.C ADDITIONAL INFORMATION:
T=4.5 CI=5.0

OVER THE LAST 6 HOURS, GRANT HAS MAINTAINED ITS PATTERN AS EMBEDDED
CENTER. THE AMSR2 SATELLITE IMAGE FROM 0928Z AND THE INFRARED IMAGES
HELPED US TO LOCATE THE CENTRE. THE SUBJECTIVE DVORAK ANALYSES AT
1200Z INDICATE A NUMBER-T OF AROUND 4.5 FOR BOTH PT AND DT METHODS.
THE CONTRIBUTION OF DETERMINISTIC MODEL ANALYSES ALLOWS US TO OPT FOR
A MAXIMUM AVERAGE WIND SPEED OF 85KT, WHICH DOWNGRADES GRANT INTO THE
TROPICAL CYCLONE LEVEL.

IN TERMS OF TRACK, IT IS SLIGHTLY FURTHER SOUTH THAN ON PREVIOUS
ANALYSIS TIME BUT WITHOUT MOVE TOO FAR FROM THEM. UNDER THE INFLUENCE
OF THE SUBTROPICAL RIDGE LOCATED SOUTH TO SOUTH-EAST, GRANT IS
EXPECTED TO CONTINUE ON A WEST-SOUTHWEST TRAJECTORY FOR ANOTHER 24
HOURS SLOWING DOWN. FROM THURSDAY (NEW YEAR'S DAY), A WESTERLY RIDGE
WILL FORCE IT TO SLOW DOWN MORE SIGNIFICANTLY AND SHOULD STEER IT
WEST-NORTH-WESTWARDS. THEN, AS ITS INTENSITY DECREASES, IT SHOULD
RESUME A WEST-SOUTHWEST TRACK DRIVEN BY THE LOW-LEVEL RIDGE. THE CMRS
FORECAST IS BASED ON A COMPROMISE BETWEEN THE BEST AVAILABLE
GUIDANCES, WHICH REMAIN SIGNIFICANTLY DISPERSED BEYOND THURSDAY DUE
TO THE POSSIBLE REINTENSIFICATION OF THE SYSTEM ENVISAGED BY CERTAIN
MODELS.

IN TERMS OF INTENSITY, ENVIRONMENTAL CONDITIONS BECOME UNFAVOURABLE:
THE NORTHEAST SHEAR HAS STRENGTHENED AND SHOULD BECOME MORE IMPACTFUL
AS THE SYSTEM SLOWS DOWN, LEADING TO INTRUSIONS OF DRY AIR AND A
RAPID WEAKENING OF GRANT BELOW CYCLONE STATUS IN THE NEXT 24 HOURS,
THEN TO TROPICAL DEPRESSION STATUS BY THE END OF THE WEEK. THE MODELS
SHOW QUITE A LOT OF VARIATION IN THE PACE AND EXTENT OF THE WEAKENING
BETWEEN NOW AND THURSDAY, BUT ALSO IN THE POSSIBILITY OF A NEW
INTENSIFICATION FROM NEXT SUNDAY ONWARDS, A SCENARIO THAT IS
MINORITY. THE DIFFERENCE IN SCENARIOS IS CLOSELY LINKED TO THE SPEED
AT WHICH THE SYSTEM MOVES, WHICH MAY OR MAY NOT ALLOW IT TO ESCAPE
MORE CLEARLY FROM THE EFFECT OF SHEARING AND THE INTRUSION OF DRY
AIR. IN THIS CONTEXT, THE RSMC PERSISTS IN ITS VIEW THAT THERE WILL
BE NO REINTENSIFICATION, ALLOWING THE SYSTEM TO PASS THROUGH IN A
MUCH WEAKER STATE WITHIN 3 DAYS.

NO SIGNIFICANT IMPACT IS EXPECTED ON INHABITED LAND OVER THE NEXT 72
HOURS.

king111807 · 2026-1-1 17:19

MFR降格強烈熱帶風暴

WTIO30 FMEE 010653
RSMC / TROPICAL CYCLONE CENTER / LA REUNION
TROPICAL CYCLONE FORECAST WARNING (SOUTH-WEST INDIAN OCEAN)

0.A WARNING NUMBER: 21/5/20252026
1.A SEVERE TROPICAL STORM 5 (GRANT)

2.A POSITION 2026/01/01 AT 0600 UTC:
WITHIN 20 NM RADIUS OF POINT 16.0 S / 68.8 E
(SIXTEEN DECIMAL ZERO DEGREES SOUTH AND
SIXTY EIGHT DECIMAL EIGHT DEGREES EAST)
MOVEMENT: WEST-NORTH-WEST 5 KT

3.A DVORAK ANALYSIS: 3.5/4.0/W 0.5/6 H

4.A CENTRAL PRESSURE: 989 HPA
5.A MAX AVERAGE WIND SPEED (10 MN): 55 KT
RADIUS OF MAXIMUM WINDS (RMW): 46 KM

6.A EXTENSION OF WIND BY QUADRANTS (KM):
28 KT NE: 75 SE: 100 SW: 150 NW: 140
34 KT NE: 0 SE: 0 SW: 95 NW: 100
48 KT NE: 0 SE: 0 SW: 0 NW: 65

7.A FIRST CLOSED ISOBAR (PRESSURE / AVERAGE DIAM): 1009 HPA / 700 KM
8.A VERTICAL EXTENSION OF CYCLONE CIRCULATION: DEEP

1.B FORECASTS (WINDS RADII IN KM):
12H: 2026/01/01 18 UTC: 15.9 S / 68.1 E, VENT MAX= 040 KT, MODERATE
TROPICAL STORM
28 KT NE: 95 SE: 120 SW: 155 NW: 130
34 KT NE: 0 SE: 75 SW: 95 NW: 85

24H: 2026/01/02 06 UTC: 15.6 S / 67.2 E, VENT MAX= 035 KT, MODERATE
TROPICAL STORM
28 KT NE: 95 SE: 150 SW: 130 NW: 120
34 KT NE: 0 SE: 75 SW: 95 NW: 75

36H: 2026/01/02 18 UTC: 15.1 S / 66.2 E, VENT MAX= 035 KT, MODERATE
TROPICAL STORM
28 KT NE: 0 SE: 155 SW: 140 NW: 95
34 KT NE: 0 SE: 0 SW: 85 NW: 0

48H: 2026/01/03 06 UTC: 15.0 S / 65.1 E, VENT MAX= 030 KT, TROPICAL
DEPRESSION
28 KT NE: 0 SE: 165 SW: 150 NW: 0

60H: 2026/01/03 18 UTC: 15.1 S / 63.8 E, VENT MAX= 030 KT, TROPICAL
DEPRESSION
28 KT NE: 0 SE: 165 SW: 130 NW: 0

72H: 2026/01/04 06 UTC: 15.4 S / 61.9 E, VENT MAX= 030 KT, TROPICAL
DEPRESSION
28 KT NE: 0 SE: 185 SW: 155 NW: 110

2.B LONGER-RANGE OUTLOOK:
96H: 2026/01/05 06 UTC: 15.8 S / 58.0 E, VENT MAX= 030 KT, TROPICAL
DEPRESSION
28 KT NE: 150 SE: 220 SW: 195 NW: 140

120H: 2026/01/06 06 UTC: 16.4 S / 53.6 E, VENT MAX= 030 KT, TROPICAL
DEPRESSION
28 KT NE: 165 SE: 260 SW: 205 NW: 155

2.C ADDITIONAL INFORMATION:
T=3.5 CI=4.0

OVER THE LAST 6 HOURS, GRANT'S WEAKENING TREND HAS CONTINUED. THE
SYSTEM NOW DISPLAYS A SHEAR PATTERN WITH A CENTER ON THE EASTERN EDGE
OF AN INTENSE CDO, WITH CLOUD TOPS BELOW -85C AND SIGNIFICANT
THUNDERSTORM ACTIVITY. THE EASTERN PART OF THE LOW-LEVEL VORTEX IS
NOW EXPOSED. SUBJECTIVE DVORAK ANALYSIS YIELDS A DT OF 3.5 WITH A
CENTER LESS THAN 20 NM FROM THE CONVECTIVE MASS. MET ADJUSTED BY PT
IS ALSO AT 3.5. A 0101Z SAR RCM1 PASS MEASURED WINDS OF 60-65 KT
(10-MIN WINDS), SHOWING A MORE ASYMMETRICAL AND ELONGATED WIND
STRUCTURE. TWO SUCCESSIVE ASCAT PASSES (ASCAT-B AT 0432Z, ASCAT-C AT
0511Z) MEASURED MAXIMUM WINDS BETWEEN 45 AND 50 KT UNDER INTENSE
CONVECTION IN THE WESTERN SEMI-CIRCLE (EQUIVALENT TO AT LEAST 55 KT
TAKING INTO ACCOUNT THE ASCAT'S UNDERESTIMATION), WHILE WINDS NO
LONGER REACH 35 KT IN THE EASTERN SEMI-CIRCLE. THEY ALSO SHOW A CLEAR
BROADENING OF THE RADIUS OF MAXIMUM WINDS. THESE VARIOUS DATA ENABLE
US TO ESTIMATE THAT GRANT IS AT SEVERE TROPICAL STORM STAGE WITH
MAXIMUM WINDS OF 55 KT IN THE NORTHWEST QUADRANT. IN ADDITION, THE
SYSTEM'S MOVEMENT HAS CONTINUED TO SLOW DOWN AND HAS BEGUN A WEST TO
WEST-NORTHWEST TURN.

IN TERMS OF TRACK FORECAST, THE SYSTEM'S SLOWDOWN WILL CONTINUE
THROUGH FRIDAY WITH A TEMPORARY WEST-NORTHWESTWARD TURN DRIVEN BY THE
BUILDING OF A RIDGE LOCATED TO THE WEST THAT WILL GRADUALLY SLIDE
SOUTH OF THE SYSTEM. FROM SATURDAY, AS THE RIDGE RETRACTS TO THE
SOUTH-SOUTHEAST, THE TRACK IS EXPECTED TO SHIFT WEST TO
WEST-SOUTHWESTWARDS. THERE REMAINS SIGNIFICANT UNCERTAINTY BOTH IN
TERMS OF FORWARD SPEED AND NORTH-SOUTH SPREAD.

IN TERMS OF INTENSITY, ENVIRONMENTAL CONDITIONS ARE BECOMING
UNFAVORABLE WITH STRONGER AND MORE IMPACTFUL SHEAR IN CONNECTION WITH
THE SYSTEM'S SLOWDOWN. THIS WILL LEAD TO DRY AIR DISRUPTION AND RAPID
WEAKENING UNTIL SATURDAY, WITH GRANT EXPECTED TO WEAKEN TO TROPICAL
DEPRESSION STAGE. THERE REMAINS HIGH UNCERTAINTY ABOUT THE INTENSITY
FORECAST, CLOSELY LINKED TO THE MOTION'S SPEED, WHICH MAKE THE SYSTEM
MORE OR LESS ESCAPE THE EFFECTS OF SHEAR AND DRY AIR INTRUSIONS. FROM
SUNDAY OR MONDAY, CONDITIONS COULD IMPROVE SLIGHTLY, AS THE
ENVIRONMENT BECOMES MOISTER AND WITH VERY WARM UNDERLYING SST. BUT
THE PERSISTENCE OF A SOUTH TO SOUTHEASTERLY SHEAR AND THE LACK OF
SURFACE CONVERGENCE COULD LIMIT CHANCES OF REINTENSIFICATION. THERE
IS A LOT OF SPREAD BETWEEN MODELS, WITH SOME (INCLUDING GFS)
FORECASTING REINTENSIFICATION AND OTHERS (SUCH AS IFS) FAVORING A
FILLING OF THE SYSTEM. IN THIS CONTEXT, THE RSMC PERSISTS FORECASTING
NO SIGNIFICANT REINTENSIFICATION, LEAVING THE SYSTEM AT A RELATIVELY
WEAK STAGE UNTIL TUESDAY, ALTHOUGH THIS WILL NEED TO BE CONFIRMED.

NO SIGNIFICANT IMPACT IS EXPECTED ON THE MAIN ISLANDS OF THE
MASCAREIGNES OVER THE NEXT 72 HOURS.
IN SAINT BRANDON, AS THE SYSTEM IS FORECAST TO PASS CLOSE BETWEEN
SUNDAY AND MONDAY, AT TROPICAL DEPRESSION STAGE ACCORDING TO THE
CURRENT FORECAST, HEAVY THUNDERY SHOWERS ARE EXPECTED. THE
PROBABILITY OF GALE-FORCE WINDS IS ESTIMATED TO BE LOW ACCORDING TO
THE CURRENT FORECAST, BUT GIVEN THE FORECAST UNCERTAINTY, THIS WILL
NEED TO BE CONFIRMED.

king111807 · 2026-1-2 02:04

MFR降格中度熱帶風暴

WTIO30 FMEE 011234
RSMC / TROPICAL CYCLONE CENTER / LA REUNION
TROPICAL CYCLONE FORECAST WARNING (SOUTH-WEST INDIAN OCEAN)

0.A WARNING NUMBER: 22/5/20252026
1.A MODERATE TROPICAL STORM 5 (GRANT)

2.A POSITION 2026/01/01 AT 1200 UTC:
WITHIN 20 NM RADIUS OF POINT 15.9 S / 68.2 E
(FIFTEEN DECIMAL NINE DEGREES SOUTH AND
SIXTY EIGHT DECIMAL TWO DEGREES EAST)
MOVEMENT: WEST 5 KT

3.A DVORAK ANALYSIS: 3.0/3.5/W 0.5/6 H

4.A CENTRAL PRESSURE: 992 HPA
5.A MAX AVERAGE WIND SPEED (10 MN): 45 KT
RADIUS OF MAXIMUM WINDS (RMW): 56 KM

6.A EXTENSION OF WIND BY QUADRANTS (KM):
28 KT NE: 75 SE: 110 SW: 150 NW: 140
34 KT NE: 0 SE: 65 SW: 95 NW: 95

7.A FIRST CLOSED ISOBAR (PRESSURE / AVERAGE DIAM): 1009 HPA / 700 KM
8.A VERTICAL EXTENSION OF CYCLONE CIRCULATION: DEEP

1.B FORECASTS (WINDS RADII IN KM):
12H: 2026/01/02 00 UTC: 15.8 S / 67.6 E, VENT MAX= 040 KT, MODERATE
TROPICAL STORM
28 KT NE: 95 SE: 120 SW: 140 NW: 130
34 KT NE: 0 SE: 75 SW: 85 NW: 75

24H: 2026/01/02 12 UTC: 15.4 S / 66.7 E, VENT MAX= 035 KT, MODERATE
TROPICAL STORM
28 KT NE: 95 SE: 110 SW: 140 NW: 120
34 KT NE: 0 SE: 0 SW: 95 NW: 65

36H: 2026/01/03 00 UTC: 15.1 S / 65.6 E, VENT MAX= 030 KT, TROPICAL
DEPRESSION
28 KT NE: 0 SE: 120 SW: 140 NW: 0

48H: 2026/01/03 12 UTC: 15.1 S / 64.4 E, VENT MAX= 030 KT, TROPICAL
DEPRESSION
28 KT NE: 0 SE: 150 SW: 155 NW: 0

60H: 2026/01/04 00 UTC: 15.4 S / 62.6 E, VENT MAX= 030 KT, TROPICAL
DEPRESSION
28 KT NE: 110 SE: 155 SW: 140 NW: 0

72H: 2026/01/04 12 UTC: 15.8 S / 60.5 E, VENT MAX= 030 KT, TROPICAL
DEPRESSION
28 KT NE: 110 SE: 165 SW: 150 NW: 120

2.B LONGER-RANGE OUTLOOK:
96H: 2026/01/05 12 UTC: 16.5 S / 56.3 E, VENT MAX= 030 KT, TROPICAL
DEPRESSION
28 KT NE: 140 SE: 185 SW: 185 NW: 140

120H: 2026/01/06 12 UTC: 17.9 S / 51.9 E, VENT MAX= 030 KT, TROPICAL
DEPRESSION
28 KT NE: 140 SE: 195 SW: 205 NW: 150

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

OVER THE LAST 6 HOURS, GRANT'S CLOUD PATTERN HAS BECOME MORE SHEARED
WITH A LOW-LEVEL VORTEX BECOMING SLIGHTLY MORE EXPOSED AT THE EASTERN
EDGE OF THE CONVECTIVE MASS AND A CENTER A LITTLE LESS THAN 30 NM
FROM THE CDO. SUBJECTIVE DVORAK ANALYSIS YIELDS A DT OF 3.0. IN
ADDITION, CLOUD TOPS HAVE WARMED COMPARED TO THIS MORNING. ESTIMATED
INTENSITY IS DOWN TO 45 KT AT 12UTC, IN LINE WITH THE DVORAK ANALYSIS
AND IN GOOD AGREEMENT WITH MOST OF CIMSS AIDS (SATCON, AIDT, DMINT).

IN TERMS OF TRACK FORECAST, THE SYSTEM'S SLOWDOWN WILL CONTINUE
THROUGH FRIDAY WITH A TEMPORARY WEST-NORTHWESTWARD MOVEMENT DRIVEN BY
THE BUILDING OF A RIDGE LOCATED TO THE WEST THAT WILL GRADUALLY SLIDE
SOUTH OF THE SYSTEM. FROM SATURDAY, AS THE RIDGE RETRACTS TO THE
SOUTH-SOUTHEAST, THE TRACK IS EXPECTED TO SHIFT WEST THEN
WEST-SOUTHWESTWARDS. THERE REMAINS SIGNIFICANT UNCERTAINTY BOTH IN
TERMS OF FORWARD SPEED AND NORTH-SOUTH SPREAD.

IN TERMS OF INTENSITY, ENVIRONMENTAL CONDITIONS ARE UNFAVORABLE IN
THE SHORT TERM WITH QUITE STRONG EAST-NORTHEASTERLY WIND SHEAR WHICH
IS NOW MORE IMPACTFUL DUE TO THE SYSTEM'S SLOWDOWN. THIS LEADS TO DRY
AIR DISRUPTION AND A WEAKENING TREND UNTIL SATURDAY, WITH GRANT
EXPECTED TO WEAKEN NEAR TROPICAL DEPRESSION STAGE. FROM SUNDAY OR
MONDAY, CONDITIONS COULD IMPROVE SLIGHTLY, WITH SLIGHTLY LOWER WIND
SHEAR, MORE MID-LEVEL MOISTURE AND WITH VERY WARM UNDERLYING SST.
HOWEVER, THE PERSISTENCE OF A MODERATE SOUTH TO SOUTHEASTERLY WIND
SHEAR AND THE LACK OF SURFACE CONVERGENCE COULD LIMIT CHANCES OF
REINTENSIFICATION. THERE IS A LOT OF SPREAD BETWEEN MODELS, WITH SOME
(INCLUDING GFS) FORECASTING REINTENSIFICATION AND OTHERS (SUCH AS
IFS) FAVORING A FILLING OF THE SYSTEM. THE RSMC PERSISTS FORECASTING
NO SIGNIFICANT REINTENSIFICATION, LEAVING THE SYSTEM AT A RELATIVELY
WEAK STAGE UNTIL TUESDAY, ALTHOUGH THIS WILL NEED TO BE CONFIRMED.

NO SIGNIFICANT IMPACT IS EXPECTED ON THE MAIN ISLANDS OF THE
MASCARENE ARCHIPELAGO OVER THE NEXT 72 HOURS.
IN SAINT BRANDON, AS THE SYSTEM IS FORECAST TO PASS CLOSE BETWEEN
SUNDAY AND MONDAY, AT TROPICAL DEPRESSION STAGE ACCORDING TO THE
CURRENT FORECAST, HEAVY THUNDERY SHOWERS ARE EXPECTED. THE
PROBABILITY OF GALE-FORCE WINDS IS ESTIMATED TO BE LOW ACCORDING TO
THE CURRENT FORECAST, BUT GIVEN THE FORECAST UNCERTAINTY, THIS WILL
NEED TO BE CONFIRMED.

king111807 · 2026-1-2 02:09

JTWC降格TS

WTXS32 PGTW 011500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/TROPICAL CYCLONE 09S (GRANT) WARNING NR 031//
RMKS/
1. TROPICAL CYCLONE 09S (GRANT) WARNING NR 031
02 ACTIVE TROPICAL CYCLONES IN SOUTHIO
MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE
WIND RADII VALID OVER OPEN WATER ONLY
---
WARNING POSITION:
011200Z --- NEAR 16.0S 68.2E
   MOVEMENT PAST SIX HOURS - 270 DEGREES AT 05 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 - 025 NM NORTHEAST QUADRANT
                        025 NM SOUTHEAST QUADRANT
                        045 NM SOUTHWEST QUADRANT
                        050 NM NORTHWEST QUADRANT
RADIUS OF 034 KT WINDS - 065 NM NORTHEAST QUADRANT
                        070 NM SOUTHEAST QUADRANT
                        070 NM SOUTHWEST QUADRANT
                        075 NM NORTHWEST QUADRANT
REPEAT POSIT: 16.0S 68.2E
---
FORECASTS:
12 HRS, VALID AT:
020000Z --- 15.9S 67.3E
MAX SUSTAINED WINDS - 040 KT, GUSTS 050 KT
WIND RADII VALID OVER OPEN WATER ONLY
RADIUS OF 034 KT WINDS - 060 NM NORTHEAST QUADRANT
                        060 NM SOUTHEAST QUADRANT
                        060 NM SOUTHWEST QUADRANT
                        060 NM NORTHWEST QUADRANT
VECTOR TO 24 HR POSIT: 295 DEG/ 05 KTS
---
24 HRS, VALID AT:
021200Z --- 15.5S 66.4E
MAX SUSTAINED WINDS - 035 KT, GUSTS 045 KT
WIND RADII VALID OVER OPEN WATER ONLY
RADIUS OF 034 KT WINDS - 010 NM NORTHEAST QUADRANT
                        040 NM SOUTHEAST QUADRANT
                        050 NM SOUTHWEST QUADRANT
                        010 NM NORTHWEST QUADRANT
VECTOR TO 36 HR POSIT: 285 DEG/ 05 KTS
---
36 HRS, VALID AT:
030000Z --- 15.2S 65.4E
MAX SUSTAINED WINDS - 035 KT, GUSTS 045 KT
WIND RADII VALID OVER OPEN WATER ONLY
RADIUS OF 034 KT WINDS - 000 NM NORTHEAST QUADRANT
                        060 NM SOUTHEAST QUADRANT
                        060 NM SOUTHWEST QUADRANT
                        000 NM NORTHWEST QUADRANT
VECTOR TO 48 HR POSIT: 270 DEG/ 07 KTS
---
EXTENDED OUTLOOK:
48 HRS, VALID AT:
031200Z --- 15.2S 64.0E
MAX SUSTAINED WINDS - 035 KT, GUSTS 045 KT
WIND RADII VALID OVER OPEN WATER ONLY
RADIUS OF 034 KT WINDS - 000 NM NORTHEAST QUADRANT
                        060 NM SOUTHEAST QUADRANT
                        060 NM SOUTHWEST QUADRANT
                        000 NM NORTHWEST QUADRANT
VECTOR TO 72 HR POSIT: 260 DEG/ 11 KTS
---
72 HRS, VALID AT:
041200Z --- 15.8S 59.6E
MAX SUSTAINED WINDS - 040 KT, GUSTS 050 KT
WIND RADII VALID OVER OPEN WATER ONLY
RADIUS OF 034 KT WINDS - 050 NM NORTHEAST QUADRANT
                        070 NM SOUTHEAST QUADRANT
                        055 NM SOUTHWEST QUADRANT
                        000 NM NORTHWEST QUADRANT
VECTOR TO 96 HR POSIT: 260 DEG/ 10 KTS
---
LONG RANGE OUTLOOK:
---
96 HRS, VALID AT:
051200Z --- 16.6S 55.5E
MAX SUSTAINED WINDS - 050 KT, GUSTS 065 KT
WIND RADII VALID OVER OPEN WATER ONLY
RADIUS OF 050 KT WINDS - 020 NM NORTHEAST QUADRANT
                        020 NM SOUTHEAST QUADRANT
                        010 NM SOUTHWEST QUADRANT
                        020 NM NORTHWEST QUADRANT
RADIUS OF 034 KT WINDS - 050 NM NORTHEAST QUADRANT
                        060 NM SOUTHEAST QUADRANT
                        040 NM SOUTHWEST QUADRANT
                        040 NM NORTHWEST QUADRANT
VECTOR TO 120 HR POSIT: 250 DEG/ 09 KTS
---
120 HRS, VALID AT:
061200Z --- 17.9S 51.8E
MAX SUSTAINED WINDS - 050 KT, GUSTS 065 KT
WIND RADII VALID OVER OPEN WATER ONLY
RADIUS OF 050 KT WINDS - 020 NM NORTHEAST QUADRANT
                        030 NM SOUTHEAST QUADRANT
                        020 NM SOUTHWEST QUADRANT
                        000 NM NORTHWEST QUADRANT
RADIUS OF 034 KT WINDS - 040 NM NORTHEAST QUADRANT
                        060 NM SOUTHEAST QUADRANT
                        060 NM SOUTHWEST QUADRANT
                        030 NM NORTHWEST QUADRANT
---
REMARKS:
011500Z POSITION NEAR 16.0S 68.0E.
01JAN26. TROPICAL CYCLONE 09S (GRANT), LOCATED APPROXIMATELY 591
NM SOUTH-SOUTHWEST OF DIEGO GARCIA, HAS TRACKED WESTWARD AT 05
KNOTS OVER THE PAST SIX HOURS.
MINIMUM CENTRAL PRESSURE AT 011200Z IS 993 MB. MAXIMUM
SIGNIFICANT WAVE HEIGHT AT 011200Z IS 21 FEET. NEXT WARNINGS AT
020300Z AND 021500Z.
REFER TO TROPICAL CYCLONE 11S (IGGY) WARNINGS (WTXS31 PGTW)
FOR SIX-HOURLY UPDATES.//
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