WDXS32 PGTW 200900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 06S (ANGGREK) WARNING 
NR 011//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 12.5S 92.6E
   INITIAL INTENSITY: 70 KTS
   GEOGRAPHIC REFERENCE: 250 NM WEST OF COCOS ISLAND
   MOVEMENT PAST 6 HOURS: WEST-SOUTHWESTWARD AT 02 KTS
   SIGNIFICANT WAVE HEIGHT: 20 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS TROPICAL
CYCLONE (TC) 06S (ANGGREK) TRACKING WEST-SOUTHWEST AT 2 KNOTS OVER THE 
LAST 12 HOURS, SIGNIFICANTLY DIFFERING FROM OUR PREVIOUS FORECAST
ANTICIPATING A TRACK OF WEST-NORTHWEST. THE MSI SHOWS STRONG
CONVECTIVE TOWERS DEVELOPING TO THE NORTH OF THE CENTER AND
WRAPPING UPSHEAR, AND A NASCENT WARM SPOT OR EYE FEATURE BEGINNING
TO APPEAR. A 200745Z AMSR2 MICROWAVE PASS REVEALED A SMALL
MICROWAVE EYE FEATURE IN BOTH THE 89GHZ AND 37GHZ BANDS, WITH SOME
SLIGHT WEST-NORTHWEST TILT WITH HEIGHT. BOTH POSITION AND INTENSITY
ARE ASSESSED WITH HIGH CONFIDENCE BASED ON AN EXTRAPOLATION OF A
CLEAR-CUT RCM-3 SAR PASS AT 172340Z THAT DEPICTS A CRISP EYE IN THE
SYMMETRICAL CYCLONE, WHICH IS SIGNIFICANTLY OBSCURED BY DEEP LAYER
CONVECTION ON MSI, AS WELL AS THE LATE AMSR2 PASS NOTED ABOVE. THE
SAR PASS ADDITIONALLY DISPLAYED WINDS OF UP TO 81 KNOTS, WHICH
SIGNIFICANTLY DIFFERS FROM THE PREVIOUS ANALYSIS INTENSITY OF 60
KNOTS BUT IS GENERALLY SUPPORTED BY THE ADT AND AIDT ESTIMATES AND
SLIGHTLY ABOVE THE AGENCY FIX INTENSITIES. THE APPARENT
INTENSIFICATION SUGGESTS THAT ACTUAL WIND SHEAR IS LESS THAN THE
GLOBAL MODELS HAD ANTICIPATED (20 KNOTS). UPPER-LEVEL OUTFLOW
REMAINS MODEST PRIMARILY LIMITED TO THE IMMEDIATE REGION AROUND
THE SYSTEM ALONG WITH A WEAK POLEWARD PUSH. HAFS CURRENTLY SHOWS
THAT SST ARE IN THE 26-27C RANGE, FURTHER SUPPORTING THE
STORM'S INTENSITY.

INITIAL WIND RADII BASIS: SAR DATA 

CURRENT STEERING MECHANISM: COMPETING STEERING ENVIRONMENT ON THE
SOUTHERN PERIPHERY OF A NEAR EQUATORIAL RIDGE (NER) TO THE NORTH
AND THE NORTHERN PERIPHERY OF A SUBTROPICAL RIDGE (STR) TO THE
SOUTH.

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T4.0 - 65 KTS
   KNES: T4.0 - 65 KTS
   DEMS: T4.0 - 65 KTS
   APRF: T3.5 - 55 KTS
   CIMSS ADT: 79 KTS AT 200530Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE
   VWS: 15-20 KTS
   SST: 27-28 CELSIUS
   OUTFLOW: MODERATE RADIAL
   OTHER FACTORS: WEAK POLEWARD OUTFLOW CHANNEL AND SIGNIFICANT DRY
AIR SURROUNDING THE SYSTEM. 

ANALYSIS CONFIDENCE:
   INITIAL POSITION: HIGH
   INITIAL INTENSITY: HIGH
   INITIAL WIND RADII: HIGH

3. FORECAST REASONING.

SIGNIFICANT FORECAST CHANGES: TROPICAL CYCLONE (TC) 06S (ANGGREK)
IS NOW ASSESSED TO BE TRACKING SOUTH-SOUTHWESTWARD WITH A STORM
INTENSITY OF 70 KNOTS. THE EXTENDED RANGE FORECAST DEVIATES
180-DEGREES FROM THE PREVIOUS FORECAST. 

FORECAST DISCUSSION: TROPICAL CYCLONE (TC) 06S (ANGGREK) IS
FORECAST TO TRACK WEST-NORTHWEST THROUGH TAU 36, THEN TRAVEL DUE
WEST THROUGH TAU 48 BEFORE CONTINUING SOUTH-SOUTHWEST AT 2 KNOTS
FOR THE REMAINDER OF THE FORECAST PERIOD. THIS IS DUE TO A
COMPETING STEERING ENVIRONMENT WITH A NER TO THE NORTH AND A STR TO
THE SOUTH. THROUGH TAU 48, THE SUBTROPICAL RIDGE IS EXPECTED TO
BUILD, FORCING THE NORTH-NORTHWEST MOTION, THEN WEAKEN AS THE NER
TO THE NORTH FORCES THE SYSTEM TO THE SOUTH. AFTER TAU 72, THE
SYSTEM TURNS SOUTHWESTWARD AS IT IS DRAWN TOWARDS A WEAKNESS IN THE
STR, INDUCED BY THE APPROACH AND PASSAGE OF A MID-LATITUDE TROUGH
TO THE SOUTH. IN TERMS OF INTENSITY, IN THE NEAR-TERM, THE SYSTEM
IS EXPECTED TO INTENSIFY TO APPROXIMATELY 75 KNOTS WITH SEA
SURFACE TEMPERATURES SUPPORT BUT WILL WEAKEN TO APPROXIMATELY 65
KNOTS GRADUALLY THROUGH TAU 36 DUE TO DRY AIR ENTRAINMENT FROM THE
WEST AND COLD SEAWATER UPWELLING RESULTING FROM THE SLOW MOVEMENT
OF THE STORM. WIND SHEAR IS ALSO EXPECTED TO INCREASE BETWEEN TAU
12-36 BEFORE WEAKENING THROUGH THE END OF THE FORECAST PERIOD,
WHICH COMBINED WITH IMPROVED UPPER-LEVEL OUTFLOW, WILL ALLOW FOR A
RENEWED INTENSIFICATION TREND AFTER TAU 72.  

MODEL DISCUSSION: DETERMINISTIC MODEL GUIDANCE IS IN GENERAL
AGREEMENT THAT TROPICAL CYCLONE (TC) 06S (ANGGREK) WILL DRIFT TO
THE NORTHWEST BEFORE TURNING SOUTH-SOUTHWEST, HOWEVER THE MODELS
DIFFER IN TIMING AND INTENSITY OF THE TURN. ECMWF ANTICIPATES THE
STEERING OF BOTH THE NORTHERN AND SOUTHERN RIDGES TO BE MORE ZONAL
WHILE THE GFS ANTICIPATES THE STEERING TO BE MORE MERIDIONAL, AND
ECMWF PARTICULARLY EXPECTS THAT THE STR TO THE SOUTH WILL NOT BUILD
AS STRONGLY AS GFS. THE BULK OF THE CONSENSUS MEMBERS SUPPORT THE
JTWC FORECAST, THOUGH NAVGEM IS DISCARDED, AND THE ECMWF AND GFS
DEPICT A SIGNIFICANTLY FASTER TRACK SPEED AFTER TAU 72. THE
FORECAST IS PLACED CLOSED TO THE CONSENSUS MEAN THROUGH THE
FORECAST PERIOD, WITH LOW CONFIDENCE. THE JTWC CONSENSUS INTENSITY
MODELS ALL GENERALLY REFLECT A GRADUAL DECREASE BETWEEN TAU 0-48,
HOWEVER, BEYOND TAU 48 THE MODELS DIFFER IN HOW RAPIDLY THE STORM
WILL REINTENSIFY DUE TO DIFFERENCES IN TRACK AND THE RESULTING
DIFFERENCES IN THE ENVIRONMENTAL PARAMETERS. GFS EXPECTS THE STORM
TO TRACK MORE SOUTHWARD, WHICH WOULD EXPOSE THE STORM TO MORE
INTENSE WIND SHEAR AND COOLER SSTS, BUT THE MORE GRADUAL TRACK OF
ECMWF WOULD EXPOSE THE STORM TO LESS WIND SHEAR AND WARMER SSTS,
ALLOWING THE REINTENSIFICATION TO BE MORE EXTREME. THE JTWC
FORECAST IS CONSISTENT WITH THE CONSENSUS MEAN, WTIH THE EXCEPTION
OF THE FIRST 12 HOURS, WHICH CALLS FOR INTENSIFICATION BASED ON THE
RECENT IMPROVEMENT IN THE SATELLITE DEPICTION. 

FORECAST CONFIDENCE:
   TRACK 0 - 72 HR: LOW
   TRACK 72-120 HR: LOW
   INTENSITY 0 - 72 HR: LOW
   INTENSITY 72-120 HR: LOW//
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