JTWC IS ISSUING 12 HOURLY WARNINGS ON TC 27S. 3 HOURLY SATELLITE BULLETINS ARE ISSUED ON TC 27S AND ON TC 28S.
SOUTH INDIAN OCEAN: TC 27S(COURTNEY). 29/00UTC ESTIMATED LOCATION AND INTENSITY. INTENSITY IS 115 KNOTS CATEGORY 4 US. INTENSITY IS +35 KNOTS OVER 24 HOURS.
2725032618 173S1022E 70
2725032700 169S1010E 75
2725032706 168S1000E 80
2725032712 168S 992E 90
2725032718 167S 981E 85
2725032800 167S 972E 80
2725032806 168S 957E 85
2725032812 171S 946E 110
2725032818 174S 930E 115
2725032900 177S 919E 115
2725032700 169S1010E 75
2725032706 168S1000E 80
2725032712 168S 992E 90
2725032718 167S 981E 85
2725032800 167S 972E 80
2725032806 168S 957E 85
2725032812 171S 946E 110
2725032818 174S 930E 115
2725032900 177S 919E 115
CLICK ON THE IMAGERY BELOW TO GET IT ANIMATED AND ENLARGED
85 – 92 GHz Polarization-Corrected Brightness Temperature
WARNING 13 ISSUED AT 28/21UTC
WDXS31 PGTW 282100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 27S (COURTNEY) WARNING
NR 013//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
SUMMARY:
INITIAL POSITION: 17.4S 93.0E
INITIAL INTENSITY: 115 KTS
GEOGRAPHIC REFERENCE: 385 NM SOUTHWEST OF THE COCOS ISLANDS
MOVEMENT PAST 6 HOURS: WESTWARD AT 16 KTS
SIGNIFICANT WAVE HEIGHT: 44 FEET
SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS A
PINHOLE EYE SURROUNDED BY A NEARLY SYMMETRICAL, COMPACT OUTFLOW
BOUNDARY OF TROPICAL CYCLONE (TC) 27S (COURTNEY). THE INITIAL
POSITION IS THEREFORE PLACED WITH HIGH CONFIDENCE BASED ON THE SMALL
(5-10 NM DIAMETER) EYE FEATURE. 281531Z METOP-C AMSUB 89 GHZ PASS
SHOWS A SYMMETRICAL MICROWAVE EYE AND CONVECTIVE STRUCTURE, WITH
SLIGHTLY STRONGER BANDING OVER THE WESTERN SEMICIRCLE. ANALYSIS
REVEALS FAVORABLE ENVIRONMENTAL CONDITIONS WITH LOW (5-10 KTS) DEEP-
LAYER VERTICAL WIND SHEAR (VWS), WARM (26-27 C) SEA SURFACE
TEMPERATURES (SST) AND GOOD RADIAL OUTFLOW. THE INITIAL INTENSITY OF
115 KTS IS ASSESSED WITH MEDIUM CONFIDENCE BASED ON DVORAK ESTIMATES
LISTED BELOW. OBJECTIVE ESTIMATES ARE STILL CATCHING UP TO THE AGENCY
FIXES, WHILE SWITCHING BETWEEN EYE AND UNIFORM SCENES, WITH RAW T-
NUMBER VALUES RANGING BETWEEN 6.2 AND 4.5 ACCORDINGLY.
INITIAL WIND RADII BASIS: 281442Z METOP-B ASCAT IMAGE
CURRENT STEERING MECHANISM: DEEP-LAYER SUBTROPICAL RIDGE (STR)
CENTERED TO THE SOUTH
AGENCY DVORAK AND AUTOMATED FIXES:
PGTW: T6.0 - 115 KTS
KNES: T6.0 - 115 KTS
APRF: T5.5 - 102 KTS
CIMSS SATCON: 91 KTS AT 281705Z
CIMSS ADT: 92 KTS AT 281830Z
CIMSS AIDT: 91 KTS AT 281830Z
CIMSS D-PRINT: 94 KTS AT 281900Z
FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
VWS: 5-10 KTS
SST: 26-27 CELSIUS
OUTFLOW: STRONG RADIAL
ANALYSIS CONFIDENCE:
INITIAL POSITION: HIGH
INITIAL INTENSITY: MEDIUM
INITIAL WIND RADII: MEDIUM
3. FORECAST REASONING.
SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO
THE FORECAST FROM THE PREVIOUS WARNING.
FORECAST DISCUSSION: TC 27S IS FORECAST TO CONTINUE TRACKING ALONG
THE NORTHWESTERN PERIPHERY OF A STR TO THE SOUTHEAST, WHILE
MAINTAINING INTENSITY FOR THE NEXT 6 TO 12 HOURS. THE SYSTEM IS
CURRENTLY ENCAPSULATED WITHIN A BROAD AREA OF DRY AIR, BUT GIVEN
ITS COMPACT NATURE, IT WILL BE AT LEAST 48 HOURS UNTIL THE DRY AIR
STARTS TO GET ENTRAINED WITHIN THE CORE OF THE VORTEX. AT THE SAME
TIME, AN UPPER-LEVEL TROUGH IS EXPECTED TO PASS TO THE SOUTH OF THE
SYSTEM AROUND TAU 48, POTENTIALLY BRIEFLY IMPROVING THE OUTFLOW.
AFTER TAU 48, TC 27S IS EXPECTED TO ROUND THE AXIS OF THE RIDGE AND
TURN SOUTHEASTWARD. AT THE SAME TIME, AS THE SYSTEM MOVES SOUTH,
THE SST WILL DECREASE TO 26 C. AT THAT TIME, DRASTICALLY INCREASING
VWS AND DRY AIR ERODING THE CORE OF THE VORTEX WILL LEAD TO RELATIVELY
QUICK WEAKENING. AROUND TAU 72, TC 27S IS FORECAST TO BEGIN
TRANSITIONING INTO A SUBTROPICAL SYSTEM, AS ITS STRUCTURE
SHALLOWS. THE LOW-LEVEL EASTERLY FLOW, ASSOCIATED WITH A STRONG
RIDGE TO THE SOUTH, WILL THEN STEER THE SYSTEM WESTWARD. TC COURTNEY
IS FORECAST TO COMPLETE DISSIPATION BY TAU 120, BEFORE IT COMPLETES
THE SUBTROPICAL TRANSITION.
MODEL DISCUSSION: NUMERICAL MODEL TRACK GUIDANCE IS IN GOOD
AGREEMENT THROUGH THE INITIAL 48 HOURS, WITH A 100 NM CROSS-TRACK
SPREAD AND 65 NM ALONG-TRACK SPREAD. THE ONLY OUTLIER WITHIN THE
CONSENSUS MEMBER GROUP IS UKMET ENSEMBLE, WHICH PREDICTS A WESTWARD
TURN AT TAU 72, WHILE THE REMAINDER OF THE GUIDANCE IS STILL ROUNDING
THE AXIS OF THE RIDGE. AT TAU 120, ALL MODEL GUIDANCE INDICATES A
STEERING PATTERN CHANGE, TRACKING THE SYSTEM WESTWARD. CROSS-TRACK
SPREAD, WITH THE EXCLUSION OF UKMET ENSEMBLE REMAINS GOOD AT 75 NM.
MEDIUM OVERALL CONFIDENCE ASSESSMENT OF THE TRACK FORECAST IS
REFLECTED BY THE TRACK LAID CLOSE TO THE MULTI-MODEL CONSENSUS,
OFFSET ONLY FOR THE UKMET ENSEMBLE GUIDANCE. INTENSITY GUIDANCE IS
IN FAIR AGREEMENT THROUGHOUT THE FORECAST AND IS PLACED WITH MEDIUM
CONFIDENCE AS WELL, AND CLOSE TO THE CONSENSUS GUIDANCE. THE INTENSITY
SPREAD REMAINS WITHIN 15 KTS THROUGHOUT THE FORECAST PERIOD, WITH THE
EXCLUSION OF THE GFS DETERMINISTIC MODEL, WHICH IS DRASTICALLY MORE
AGGRESSIVE IN REGARD TO THE INITIAL WEAKENING TREND. AFTER TAU 72,
GFS ESTIMATES GET WITHIN THE SAME UNCERTAINTY SPREAD AS OTHER MODELS.
ALL AVAILABLE NUMERICAL MODEL GUIDANCE MEMBERS INDICATE DISSIPATION BY
TAU 120.
FORECAST CONFIDENCE:
TRACK 0 - 72 HR: MEDIUM
TRACK 72-120 HR: MEDIUM
INTENSITY 0 - 72 HR: MEDIUM
INTENSITY 72-120 HR: MEDIUM//
NNNN
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 27S (COURTNEY) WARNING
NR 013//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
SUMMARY:
INITIAL POSITION: 17.4S 93.0E
INITIAL INTENSITY: 115 KTS
GEOGRAPHIC REFERENCE: 385 NM SOUTHWEST OF THE COCOS ISLANDS
MOVEMENT PAST 6 HOURS: WESTWARD AT 16 KTS
SIGNIFICANT WAVE HEIGHT: 44 FEET
SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS A
PINHOLE EYE SURROUNDED BY A NEARLY SYMMETRICAL, COMPACT OUTFLOW
BOUNDARY OF TROPICAL CYCLONE (TC) 27S (COURTNEY). THE INITIAL
POSITION IS THEREFORE PLACED WITH HIGH CONFIDENCE BASED ON THE SMALL
(5-10 NM DIAMETER) EYE FEATURE. 281531Z METOP-C AMSUB 89 GHZ PASS
SHOWS A SYMMETRICAL MICROWAVE EYE AND CONVECTIVE STRUCTURE, WITH
SLIGHTLY STRONGER BANDING OVER THE WESTERN SEMICIRCLE. ANALYSIS
REVEALS FAVORABLE ENVIRONMENTAL CONDITIONS WITH LOW (5-10 KTS) DEEP-
LAYER VERTICAL WIND SHEAR (VWS), WARM (26-27 C) SEA SURFACE
TEMPERATURES (SST) AND GOOD RADIAL OUTFLOW. THE INITIAL INTENSITY OF
115 KTS IS ASSESSED WITH MEDIUM CONFIDENCE BASED ON DVORAK ESTIMATES
LISTED BELOW. OBJECTIVE ESTIMATES ARE STILL CATCHING UP TO THE AGENCY
FIXES, WHILE SWITCHING BETWEEN EYE AND UNIFORM SCENES, WITH RAW T-
NUMBER VALUES RANGING BETWEEN 6.2 AND 4.5 ACCORDINGLY.
INITIAL WIND RADII BASIS: 281442Z METOP-B ASCAT IMAGE
CURRENT STEERING MECHANISM: DEEP-LAYER SUBTROPICAL RIDGE (STR)
CENTERED TO THE SOUTH
AGENCY DVORAK AND AUTOMATED FIXES:
PGTW: T6.0 - 115 KTS
KNES: T6.0 - 115 KTS
APRF: T5.5 - 102 KTS
CIMSS SATCON: 91 KTS AT 281705Z
CIMSS ADT: 92 KTS AT 281830Z
CIMSS AIDT: 91 KTS AT 281830Z
CIMSS D-PRINT: 94 KTS AT 281900Z
FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
VWS: 5-10 KTS
SST: 26-27 CELSIUS
OUTFLOW: STRONG RADIAL
ANALYSIS CONFIDENCE:
INITIAL POSITION: HIGH
INITIAL INTENSITY: MEDIUM
INITIAL WIND RADII: MEDIUM
3. FORECAST REASONING.
SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO
THE FORECAST FROM THE PREVIOUS WARNING.
FORECAST DISCUSSION: TC 27S IS FORECAST TO CONTINUE TRACKING ALONG
THE NORTHWESTERN PERIPHERY OF A STR TO THE SOUTHEAST, WHILE
MAINTAINING INTENSITY FOR THE NEXT 6 TO 12 HOURS. THE SYSTEM IS
CURRENTLY ENCAPSULATED WITHIN A BROAD AREA OF DRY AIR, BUT GIVEN
ITS COMPACT NATURE, IT WILL BE AT LEAST 48 HOURS UNTIL THE DRY AIR
STARTS TO GET ENTRAINED WITHIN THE CORE OF THE VORTEX. AT THE SAME
TIME, AN UPPER-LEVEL TROUGH IS EXPECTED TO PASS TO THE SOUTH OF THE
SYSTEM AROUND TAU 48, POTENTIALLY BRIEFLY IMPROVING THE OUTFLOW.
AFTER TAU 48, TC 27S IS EXPECTED TO ROUND THE AXIS OF THE RIDGE AND
TURN SOUTHEASTWARD. AT THE SAME TIME, AS THE SYSTEM MOVES SOUTH,
THE SST WILL DECREASE TO 26 C. AT THAT TIME, DRASTICALLY INCREASING
VWS AND DRY AIR ERODING THE CORE OF THE VORTEX WILL LEAD TO RELATIVELY
QUICK WEAKENING. AROUND TAU 72, TC 27S IS FORECAST TO BEGIN
TRANSITIONING INTO A SUBTROPICAL SYSTEM, AS ITS STRUCTURE
SHALLOWS. THE LOW-LEVEL EASTERLY FLOW, ASSOCIATED WITH A STRONG
RIDGE TO THE SOUTH, WILL THEN STEER THE SYSTEM WESTWARD. TC COURTNEY
IS FORECAST TO COMPLETE DISSIPATION BY TAU 120, BEFORE IT COMPLETES
THE SUBTROPICAL TRANSITION.
MODEL DISCUSSION: NUMERICAL MODEL TRACK GUIDANCE IS IN GOOD
AGREEMENT THROUGH THE INITIAL 48 HOURS, WITH A 100 NM CROSS-TRACK
SPREAD AND 65 NM ALONG-TRACK SPREAD. THE ONLY OUTLIER WITHIN THE
CONSENSUS MEMBER GROUP IS UKMET ENSEMBLE, WHICH PREDICTS A WESTWARD
TURN AT TAU 72, WHILE THE REMAINDER OF THE GUIDANCE IS STILL ROUNDING
THE AXIS OF THE RIDGE. AT TAU 120, ALL MODEL GUIDANCE INDICATES A
STEERING PATTERN CHANGE, TRACKING THE SYSTEM WESTWARD. CROSS-TRACK
SPREAD, WITH THE EXCLUSION OF UKMET ENSEMBLE REMAINS GOOD AT 75 NM.
MEDIUM OVERALL CONFIDENCE ASSESSMENT OF THE TRACK FORECAST IS
REFLECTED BY THE TRACK LAID CLOSE TO THE MULTI-MODEL CONSENSUS,
OFFSET ONLY FOR THE UKMET ENSEMBLE GUIDANCE. INTENSITY GUIDANCE IS
IN FAIR AGREEMENT THROUGHOUT THE FORECAST AND IS PLACED WITH MEDIUM
CONFIDENCE AS WELL, AND CLOSE TO THE CONSENSUS GUIDANCE. THE INTENSITY
SPREAD REMAINS WITHIN 15 KTS THROUGHOUT THE FORECAST PERIOD, WITH THE
EXCLUSION OF THE GFS DETERMINISTIC MODEL, WHICH IS DRASTICALLY MORE
AGGRESSIVE IN REGARD TO THE INITIAL WEAKENING TREND. AFTER TAU 72,
GFS ESTIMATES GET WITHIN THE SAME UNCERTAINTY SPREAD AS OTHER MODELS.
ALL AVAILABLE NUMERICAL MODEL GUIDANCE MEMBERS INDICATE DISSIPATION BY
TAU 120.
FORECAST CONFIDENCE:
TRACK 0 - 72 HR: MEDIUM
TRACK 72-120 HR: MEDIUM
INTENSITY 0 - 72 HR: MEDIUM
INTENSITY 72-120 HR: MEDIUM//
NNNN
29/0230UTC SATELLITE BULLETIN
TPXS11 PGTW 290318
A. TROPICAL CYCLONE 27S (COURTNEY)
B. 29/0230Z
C. 17.73S
D. 91.47E
E. ONE/GK2A
F. T6.0/6.0/D1.5/24HRS STT: S0.0/03HRS
G. IR/EIR/VIS/MSI
H. REMARKS: 07A/PBO IRREG EYE/ANMTN. OW EYE SURROUNDED BY B YIELDS
AN E# OF 5.5. ADDED 0.5 EYE ADJUSTMENT FOR W, TO YIELD A DT OF 6.0.
MET/PT AGREES. DBO DT.
I. ADDITIONAL POSITIONS:
28/2137Z 17.52S 92.35E SSMS
28/2327Z 17.63S 91.98E SSMS
29/0030Z 17.67S 91.87E SSMS
DARLOW
A. TROPICAL CYCLONE 27S (COURTNEY)
B. 29/0230Z
C. 17.73S
D. 91.47E
E. ONE/GK2A
F. T6.0/6.0/D1.5/24HRS STT: S0.0/03HRS
G. IR/EIR/VIS/MSI
H. REMARKS: 07A/PBO IRREG EYE/ANMTN. OW EYE SURROUNDED BY B YIELDS
AN E# OF 5.5. ADDED 0.5 EYE ADJUSTMENT FOR W, TO YIELD A DT OF 6.0.
MET/PT AGREES. DBO DT.
I. ADDITIONAL POSITIONS:
28/2137Z 17.52S 92.35E SSMS
28/2327Z 17.63S 91.98E SSMS
29/0030Z 17.67S 91.87E SSMS
DARLOW
SOUTH INDIAN OCEA/WESTERN NORTH AUSTRALIA: TC 28S(DIANNE). WARNING 4/FINAL.
REMARKS: 282100Z POSITION NEAR 16.6S 123.8E. 28MAR25. TROPICAL CYCLONE 28S (DIANNE), LOCATED APPROXIMATELY 137 NM NORTHEAST OF BROOME, AUSTRALIA, HAS TRACKED SOUTHWARD AT 07 KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED (EIR) IMAGERY, COMBINED WITH RADAR IMAGERY FROM BROOME, AUSTRALIA REVEAL THAT TC 28S HAS MADE LANDFALL SOUTHEAST OF THE KOOLAND ISLAND AND IS FORECAST TO CONTINUE TRACKING SOUTHWARD. SURFACE PRESSURE AND WIND DIRECTION OBSERVATIONS SUPPORT THE ASSESSED POSITION AS WELL. TC DIANNE WILL MAINTAIN 40-45 KTS INTENSITY FOR THE NEXT SIX HOURS, BUT IS FORECAST TO START WEAKENING MORE RAPIDLY ONCE IT PASSES SOUTH OF THE KING SOUND. TC 28S WILL FULLY DISSIPATE OVER LAND BY TAU 24, AFTER WHICH THE REMNANTS OF THE VORTEX WILL TRACK SOUTHEASTWARD AND FURTHER INLAND. THIS IS THE FINAL WARNING ON THIS SYSTEM BY THE JOINT TYPHOON WRNCEN PEARL HARBOR HI. THE SYSTEM WILL BE CLOSELY MONITORED FOR SIGNS OF REGENERATION. MINIMUM CENTRAL PRESSURE AT 281800Z IS 991 MB.
2825032406 170S1222E 15
2825032412 170S1219E 15
2825032418 169S1216E 15
2825032500 167S1213E 15
2825032506 165S1212E 15
2825032512 161S1212E 15
2825032518 159S1212E 25
2825032600 157S1213E 25
2825032606 151S1209E 25
2825032612 147S1208E 25
2825032618 142S1210E 25
2825032700 138S1214E 30
2825032706 137S1219E 30
2825032712 137S1225E 30
2825032718 139S1231E 30
2825032800 143S1235E 35
2825032806 148S1237E 40
2825032812 155S1238E 45
2825032818 162S1238E 45
2825032412 170S1219E 15
2825032418 169S1216E 15
2825032500 167S1213E 15
2825032506 165S1212E 15
2825032512 161S1212E 15
2825032518 159S1212E 25
2825032600 157S1213E 25
2825032606 151S1209E 25
2825032612 147S1208E 25
2825032618 142S1210E 25
2825032700 138S1214E 30
2825032706 137S1219E 30
2825032712 137S1225E 30
2825032718 139S1231E 30
2825032800 143S1235E 35
2825032806 148S1237E 40
2825032812 155S1238E 45
2825032818 162S1238E 45
