WDXS32 PGTW 251500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 09S (GRANT) WARNING NR 
017//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 12.3S 95.0E
   INITIAL INTENSITY: 45 KTS
   GEOGRAPHIC REFERENCE: 112 NM WEST OF THE COCOS ISLANDS
   MOVEMENT PAST 6 HOURS: WESTWARD AT 06 KTS
   SIGNIFICANT WAVE HEIGHT: 15 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
TROPICAL CYCLONE (TC) 09S (GRANT) CONTINUES TO MAINTAIN COMPACT
STRUCTURE WITH DEEP CONVECTION WRAPPING TIGHTLY AROUND THE LOW
LEVEL CIRCULATION CENTER AS DEPICTED BY ANIMATED ENHANCED INFRARED
(EIR) SATELLITE IMAGERY. CLOUD TOP TEMPERATURES HAVE COOLED OVER
THE PAST SIX HOURS WITH MOST ACTIVITY IN THE NORTHERN SEMICIRCLE. A
251202Z SENTINEL-1C SAR IMAGE SUPPORTS THE INITIAL POSITION AND
INDICATES A 43 KNOTS MEAN VMAX, WITH A PEAK VALUE OF 55 KNOTS OVER
THE SOUTHEASTERN QUADRANT. THE INITIAL POSITION IS PLACED WITH HIGH
CONFIDENCE BASED ON THE PREVIOUSLY MENTIONED SAR PASS AND AGENCY
FIXES. THE INITIAL INTENSITY OF 45 KTS IS ASSESSED WITH HIGH
CONFIDENCE BASED ON THE 251202Z SAR WIND SPEED VALUES AND THE
SUBJECTIVE AND OBJECTIVE ESTIMATES LISTED BELOW.

INITIAL WIND RADII BASIS: OBJECTIVE BEST TRACK 

CURRENT STEERING MECHANISM: SUBTROPICAL RIDGE TO THE SOUTH

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T3.0 - 45 KTS
   APRF: T3.0 - 45 KTS
   CIMSS SATCON: 45 KTS AT 251300Z
   CIMSS ADT: 45 KTS AT 2501300Z
   CIMSS AIDT: 36 KTS AT 251300Z
   CIMSS D-MINT: 41 KTS AT 251152Z
   CIMSS D-PRINT: 48 KTS AT 251300Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE
   VWS: 20-25 KTS
   SST: 27-28 CELSIUS
   OUTFLOW: MODERATE POLEWARD AND EQUATORWARD

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

3. FORECAST REASONING.

SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO
THE FORECAST FROM THE PREVIOUS WARNING.

FORECAST DISCUSSION: TROPICAL CYCLONE (TC) 09S (GRANT) WILL
CONTINUE TRACKING WESTWARD UNDER THE INFLUENCE OF SUBTROPICAL
RIDGING TO THE SOUTH WHILE STRUGGLING AGAINST MODERATE VERTICAL
WIND SHEAR (20-25 KTS) AND DRY AIR INTRUSION. THESE FORECASTED
CONDITIONS WILL ONLY ALLOW THE SYSTEM TO INTENSIFY UP TO 55 KTS
AROUND TAU 36. AFTER TAU 72 THE DECREASE IN FORECASTED VERTICAL
WIND SHEAR AND A BETTER OUTFLOW WILL ALLOW THE CIRCULATION TO
UNDERGO ANOTHER PERIOD OF INTENSIFICATION WITH A PEAK INTENSITY
EXPECTED TO REACH 75 KTS BY TAU 120.

MODEL DISCUSSION: CROSS-TRACK SPREAD AMONG THE MULTI MODEL GUIDANCE
IS UNDER 100 NM UNTIL TAU 60 SHOWING GOOD AGREEMENT IN THE FIRST
HALF OF THE FORECAST. AFTERWARDS, THE SPREAD INCREASES WITH NAVGEM
STILL REPRESENTING THE MOST SOUTHERN TRACK. THE JTWC OFFICIAL
FORECAST TRACK LIES CLOSE TO THE MULTI MODEL CONSENSUS ADJUSTING
FOR THE OUTLYING NAVGEM FORECAST. THE JTWC FORECAST INTENSITY
REFLECTS VALUES CLOSE TO THE MULTI MODEL CONSENSUS THOUGH HAFS-A
AND HWRF DEPICT HIGHER INTENSIFICATION VALUES AFTER TAU 72. 

FORECAST CONFIDENCE:
   TRACK 00-72 HR: HIGH
   TRACK 72-120 HR: MEDIUM
   INTENSITY 00-72 HR: HIGH
   INTENSITY 72-120 HR: MEDIUM//
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