JTWC IS ISSUING 12 HOURLY WARNINGS ON TC 27S. 3 HOURLY SATELLITE BULLETINS ARE ISSUED ON TC 27S AND ON THE REMNANTS OF TC 28S.
SOUTH INDIAN OCEAN: TC 27S(COURTNEY). 29/00UTC ESTIMATED LOCATION AND INTENSITY. INTENSITY IS 115 KNOTS CATEGORY 4 US.
ESTIMATED PEAK INTENSITY WAS 130 KNOTS CATEGORY 4 US/SUPER TYPHOON
2725032818 174S 931E 115
2725032900 176S 921E 115
2725032906 180S 910E 120
2725032912 186S 901E 130
2725032918 195S 893E 125
2725033000 202S 889E 115
2725032900 176S 921E 115
2725032906 180S 910E 120
2725032912 186S 901E 130
2725032918 195S 893E 125
2725033000 202S 889E 115
CLICK ON THE IMAGERY BELOW TO GET IT ANIMATED AND ENLARGED
30 0018UTC 85 – 92 GHz Brightness Temperature
WARNING 15 ISSUED AT 29/21UTC
WDXS31 PGTW 292100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 27S (COURTNEY) WARNING
NR 015//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
SUMMARY:
INITIAL POSITION: 19.5S 89.3E
INITIAL INTENSITY: 125 KTS
GEOGRAPHIC REFERENCE: 620 NM SOUTHWEST OF THE COCOS ISLANDS
MOVEMENT PAST 6 HOURS: SOUTHWESTWARD AT 12 KTS
SIGNIFICANT WAVE HEIGHT: 46 FEET
SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS A
SYMMETRICAL CENTRAL DENSE OVERCAST (CDO) WITH A COMPACT EYE FEATURE
ASSOCIATED WITH TROPICAL CYCLONE (TC) 27S (COURTNEY). AS THE SYSTEM
IS TRANSITING SOUTHWESTWARD ALONG THE NORTHWESTERN PERIPHERY OF A
STR TO THE SOUTHEAST, IT IS SHOWING SIGNS OF SLIGHT WEAKENING.
ANALYSIS REVEALS THAT THE SYSTEM REACHED ITS PEAK OF 130-135 KTS
WITHIN THE LAST 6-12 HOURS. OVER THE LAST TWO HOURS HOWEVER, THE
EYE HAS BEEN CONTRACTING, COOLING AND BEGINNING TO FILL. EYE
TEMPERATURE IS CURRENTLY ANALYZED AT -24 C, WHICH IS OVER 30
DEGREES COOLER THAN 12 HOURS AGO. THE ENVIRONMENTAL ANALYSIS
REVEALS FAVORABLE CONDITIONS, WITH LOW (5-10 KTS) VERTICAL WIND
SHEAR (VWS), MODERATELY WARM (26-27 C) SEA SURFACE TEMPERATURES
(SST), GOOD RADIAL OUTFLOW, AS WELL AS GOOD AMOUNT OF MONSOONAL,
DEEP-LAYER MOISTURE. THE INITIAL POSITION IS PLACED WITH HIGH
CONFIDENCE BASED ON THE SMALL EYE FEATURE PRESENT IN THE EIR
IMAGERY LOOP, CONSISTENT WITH THE MICROWAVE EYE VISIBLE IN THE
291753Z GMI 37 GHZ IMAGE. TC COURTNEY CONVECTIVE STRUCTURE IN THIS
MICROWAVE IMAGE HINTS AT THE INCOMPLETE EYEWALL REPLACEMENT CYCLE
(ERC), WHICH IS ALSO INDICATED BY MUCH LOWER (10-15 PERCENT) M-PERC
ERC PROBABILITY FROM CIMSS, AS COMPARED TO THE ONE FROM 12 HOURS AGO.
THE INITIAL INTENSITY OF 125 KTS IS ASSESSED WITH MEDIUM CONFIDENCE
BASED ON THE SLIGHT WEAKENING TREND INDICATED BY THE AGENCY DVORAK
ESTIMATES LISTED BELOW, AS WELL AS THE OBJECTIVE FIXES FROM ADT,
AIDT AND D-PRINT ALL OSCILLATING AROUND 125 KTS.
INITIAL WIND RADII BASIS: 291513 METOP-C ASCAT SCATTEROMETER DATA
CURRENT STEERING MECHANISM: DEEP-LAYER SUBTROPICAL RIDGE (STR) TO
THE SOUTHEAST
AGENCY DVORAK AND AUTOMATED FIXES:
PGTW: T7.0 - 140 KTS
KNES: T6.5 - 127 KTS
DEMS: T7.0 - 140 KTS
FMEE: T7.0 - 140 KTS
FIMP: T7.0 - 140 KTS
CIMSS ADT: 127 KTS AT 291815Z
CIMSS AIDT: 124 KTS AT 291715Z
CIMSS D-PRINT: 123 KTS AT 291715Z
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: HIGH
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
SOUTHWESTWARD, AS IT APPROACHES THE AXIS OF A STR TO THE SOUTHEAST.
THE ENVIRONMENTAL CONDITIONS ARE EXPECTED TO REMAIN MARGINALLY
FAVORABLE OVER THE NEXT 18-24 HOURS, WITH THE EXCEPTION OF COOLING
SST, AS THE SYSTEM TRACKS POLEWARD. AT THE SAME TIME, BY TAU 24, VWS
WILL BEGIN TO SIGNIFICANTLY INCREASE, EXCEEDING 25 KTS, WHICH
COMBINED WITH COOL (24-25 C) SST AND INCREASING DRY AIR ENTRAINMENT
FROM THE NORTH, WILL CREATE A MUCH MORE HOSTILE ENVIRONMENT, LEADING
TO A CONTINUOUS WEAKENING OF THE SYSTEM. ADDITIONALLY, COAMPS-TC
EPS INTENSITY IS HINTING AT MODERATE TO RAPID WEAKENING OUT TO TAU
48. AFTERWARDS, TC 27S IS FORECAST TO BEGIN TRANSITIONING INTO A
SUBTROPICAL SYSTEM, AS ITS STRUCTURE SHALLOWS OUT, DUE TO
DRASTICALLY INCREASING VWS. STRONG LOW-LEVEL RIDGE TO THE SOUTH
WILL THEN CAUSE TC COURTNEY TO SLOW DOWN AND THEN BE STEERED
WESTWARD. THE SYSTEM IS FORECAST TO DISSIPATE BY TAU 96, PRIOR TO
COMPLETION OF THE SUBTROPICAL TRANSITION.
MODEL DISCUSSION: SHORT TERM NUMERICAL MODEL TRACK GUIDANCE IS IN
GOOD AGREEMENT, WITH ALL GUIDANCE PREDICTING STORM MOVEMENT ALONG
THE PERIPHERY OF A STR AND JTWC TRACK FORECAST ASSESSED WITH HIGH
CONFIDENCE. CROSS-TRACK SPREAD PRIOR TO THE SYSTEM SLOWING DOWN AT
TAU 48 IS 100 NM, WITH ONLY NAVGEM SHOWING A FASTER MOVEMENT,
LEADING TO THE SYSTEM GOING FURTHER EAST. AFTER TAU 48, ALL
REMAINING GUIDANCE DEPICTS TC COURTNEY TRACKING WESTWARD, BUT THE
FORECAST ENVELOPE INCREASES TO A CROSS-TRACK SPREAD OF A 150 NM BY
THE END OF THE FORECAST PERIOD. ALONG-TRACK SPREAD BY TAU 96 IS
OVER 220 NM, EXCLUDING NAVGEM, RESULTING IN A MEDIUM CONFIDENCE OF THE
LONG TERM TRACK FORECAST. INTENSITY GUIDANCE IS IN FAIR AGREEMENT,
WITH ALL OF THE MULTI-MODEL CONSENSUS MEMBERS INDICATING STEADY
WEAKENING THROUGHOUT THE FORECAST PERIOD. HOWEVER, THE DISSIPATION
TIMELINE RANGES BETWEEN TAU 60 AND 96, RESULTING IN MEDIUM INTENSITY
FORECAST CONFIDENCE ASSESSMENT. JTWC INTENSITY FORECAST IS SET
SLIGHTLY ABOVE THE CONSENSUS MEAN AND CLOSE TO THE HAFS-A GUIDANCE.
FORECAST CONFIDENCE:
TRACK 0 - 72 HR: HIGH
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 015//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
SUMMARY:
INITIAL POSITION: 19.5S 89.3E
INITIAL INTENSITY: 125 KTS
GEOGRAPHIC REFERENCE: 620 NM SOUTHWEST OF THE COCOS ISLANDS
MOVEMENT PAST 6 HOURS: SOUTHWESTWARD AT 12 KTS
SIGNIFICANT WAVE HEIGHT: 46 FEET
SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS A
SYMMETRICAL CENTRAL DENSE OVERCAST (CDO) WITH A COMPACT EYE FEATURE
ASSOCIATED WITH TROPICAL CYCLONE (TC) 27S (COURTNEY). AS THE SYSTEM
IS TRANSITING SOUTHWESTWARD ALONG THE NORTHWESTERN PERIPHERY OF A
STR TO THE SOUTHEAST, IT IS SHOWING SIGNS OF SLIGHT WEAKENING.
ANALYSIS REVEALS THAT THE SYSTEM REACHED ITS PEAK OF 130-135 KTS
WITHIN THE LAST 6-12 HOURS. OVER THE LAST TWO HOURS HOWEVER, THE
EYE HAS BEEN CONTRACTING, COOLING AND BEGINNING TO FILL. EYE
TEMPERATURE IS CURRENTLY ANALYZED AT -24 C, WHICH IS OVER 30
DEGREES COOLER THAN 12 HOURS AGO. THE ENVIRONMENTAL ANALYSIS
REVEALS FAVORABLE CONDITIONS, WITH LOW (5-10 KTS) VERTICAL WIND
SHEAR (VWS), MODERATELY WARM (26-27 C) SEA SURFACE TEMPERATURES
(SST), GOOD RADIAL OUTFLOW, AS WELL AS GOOD AMOUNT OF MONSOONAL,
DEEP-LAYER MOISTURE. THE INITIAL POSITION IS PLACED WITH HIGH
CONFIDENCE BASED ON THE SMALL EYE FEATURE PRESENT IN THE EIR
IMAGERY LOOP, CONSISTENT WITH THE MICROWAVE EYE VISIBLE IN THE
291753Z GMI 37 GHZ IMAGE. TC COURTNEY CONVECTIVE STRUCTURE IN THIS
MICROWAVE IMAGE HINTS AT THE INCOMPLETE EYEWALL REPLACEMENT CYCLE
(ERC), WHICH IS ALSO INDICATED BY MUCH LOWER (10-15 PERCENT) M-PERC
ERC PROBABILITY FROM CIMSS, AS COMPARED TO THE ONE FROM 12 HOURS AGO.
THE INITIAL INTENSITY OF 125 KTS IS ASSESSED WITH MEDIUM CONFIDENCE
BASED ON THE SLIGHT WEAKENING TREND INDICATED BY THE AGENCY DVORAK
ESTIMATES LISTED BELOW, AS WELL AS THE OBJECTIVE FIXES FROM ADT,
AIDT AND D-PRINT ALL OSCILLATING AROUND 125 KTS.
INITIAL WIND RADII BASIS: 291513 METOP-C ASCAT SCATTEROMETER DATA
CURRENT STEERING MECHANISM: DEEP-LAYER SUBTROPICAL RIDGE (STR) TO
THE SOUTHEAST
AGENCY DVORAK AND AUTOMATED FIXES:
PGTW: T7.0 - 140 KTS
KNES: T6.5 - 127 KTS
DEMS: T7.0 - 140 KTS
FMEE: T7.0 - 140 KTS
FIMP: T7.0 - 140 KTS
CIMSS ADT: 127 KTS AT 291815Z
CIMSS AIDT: 124 KTS AT 291715Z
CIMSS D-PRINT: 123 KTS AT 291715Z
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: HIGH
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
SOUTHWESTWARD, AS IT APPROACHES THE AXIS OF A STR TO THE SOUTHEAST.
THE ENVIRONMENTAL CONDITIONS ARE EXPECTED TO REMAIN MARGINALLY
FAVORABLE OVER THE NEXT 18-24 HOURS, WITH THE EXCEPTION OF COOLING
SST, AS THE SYSTEM TRACKS POLEWARD. AT THE SAME TIME, BY TAU 24, VWS
WILL BEGIN TO SIGNIFICANTLY INCREASE, EXCEEDING 25 KTS, WHICH
COMBINED WITH COOL (24-25 C) SST AND INCREASING DRY AIR ENTRAINMENT
FROM THE NORTH, WILL CREATE A MUCH MORE HOSTILE ENVIRONMENT, LEADING
TO A CONTINUOUS WEAKENING OF THE SYSTEM. ADDITIONALLY, COAMPS-TC
EPS INTENSITY IS HINTING AT MODERATE TO RAPID WEAKENING OUT TO TAU
48. AFTERWARDS, TC 27S IS FORECAST TO BEGIN TRANSITIONING INTO A
SUBTROPICAL SYSTEM, AS ITS STRUCTURE SHALLOWS OUT, DUE TO
DRASTICALLY INCREASING VWS. STRONG LOW-LEVEL RIDGE TO THE SOUTH
WILL THEN CAUSE TC COURTNEY TO SLOW DOWN AND THEN BE STEERED
WESTWARD. THE SYSTEM IS FORECAST TO DISSIPATE BY TAU 96, PRIOR TO
COMPLETION OF THE SUBTROPICAL TRANSITION.
MODEL DISCUSSION: SHORT TERM NUMERICAL MODEL TRACK GUIDANCE IS IN
GOOD AGREEMENT, WITH ALL GUIDANCE PREDICTING STORM MOVEMENT ALONG
THE PERIPHERY OF A STR AND JTWC TRACK FORECAST ASSESSED WITH HIGH
CONFIDENCE. CROSS-TRACK SPREAD PRIOR TO THE SYSTEM SLOWING DOWN AT
TAU 48 IS 100 NM, WITH ONLY NAVGEM SHOWING A FASTER MOVEMENT,
LEADING TO THE SYSTEM GOING FURTHER EAST. AFTER TAU 48, ALL
REMAINING GUIDANCE DEPICTS TC COURTNEY TRACKING WESTWARD, BUT THE
FORECAST ENVELOPE INCREASES TO A CROSS-TRACK SPREAD OF A 150 NM BY
THE END OF THE FORECAST PERIOD. ALONG-TRACK SPREAD BY TAU 96 IS
OVER 220 NM, EXCLUDING NAVGEM, RESULTING IN A MEDIUM CONFIDENCE OF THE
LONG TERM TRACK FORECAST. INTENSITY GUIDANCE IS IN FAIR AGREEMENT,
WITH ALL OF THE MULTI-MODEL CONSENSUS MEMBERS INDICATING STEADY
WEAKENING THROUGHOUT THE FORECAST PERIOD. HOWEVER, THE DISSIPATION
TIMELINE RANGES BETWEEN TAU 60 AND 96, RESULTING IN MEDIUM INTENSITY
FORECAST CONFIDENCE ASSESSMENT. JTWC INTENSITY FORECAST IS SET
SLIGHTLY ABOVE THE CONSENSUS MEAN AND CLOSE TO THE HAFS-A GUIDANCE.
FORECAST CONFIDENCE:
TRACK 0 - 72 HR: HIGH
TRACK 72-120 HR: MEDIUM
INTENSITY 0 - 72 HR: MEDIUM
INTENSITY 72-120 HR: MEDIUM//
NNNN
30/0230UTC SATELLITE BULLETIN
TPXS11 PGTW 300257
A. TROPICAL CYCLONE 27S (COURTNEY)
B. 30/0230Z
C. 20.55S
D. 88.60E
E. FOUR/GK2A
F. T5.0/6.0/W1.0/24HRS STT: W1.0/03HRS
G. IR/EIR/VIS/MSI
H. REMARKS: 28A/PBO LRG CDO/ANMTN. WELL-DEFINED CDO OF 100NM IN
DIAMETER YIELDS A CF OF 4.0. ADDED 0.5 FOR BF TO YIELD A DT OF 4.5.
MET AND PT YIELD 5.0. DBO MET. BROKE CONSTRAINTS DUE TO RAPID
WEAKENING.
I. ADDITIONAL POSITIONS:
29/2124Z 19.78S 88.98E SSMS
30/0017Z 20.10S 88.80E SSMS
HU
A. TROPICAL CYCLONE 27S (COURTNEY)
B. 30/0230Z
C. 20.55S
D. 88.60E
E. FOUR/GK2A
F. T5.0/6.0/W1.0/24HRS STT: W1.0/03HRS
G. IR/EIR/VIS/MSI
H. REMARKS: 28A/PBO LRG CDO/ANMTN. WELL-DEFINED CDO OF 100NM IN
DIAMETER YIELDS A CF OF 4.0. ADDED 0.5 FOR BF TO YIELD A DT OF 4.5.
MET AND PT YIELD 5.0. DBO MET. BROKE CONSTRAINTS DUE TO RAPID
WEAKENING.
I. ADDITIONAL POSITIONS:
29/2124Z 19.78S 88.98E SSMS
30/0017Z 20.10S 88.80E SSMS
HU
OVER-LAND REMNANTS OF TC 278S(DIANNE).
WESTERN NORTH PACIFIC/SOUTH CHINA SEA: INVEST 97W. 30/00UTC ESTIMATED LOCATION AND INTENSITY.
