WDPS31 PGTW 131500 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 03P (RUBY) WARNING NR 008// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. SUMMARY: INITIAL POSITION: 19.2S 162.3E INITIAL INTENSITY: 65 KTS GEOGRAPHIC REFERENCE: 275 NM NORTHWEST OF NOUMEA, NEW CALEDONIA MOVEMENT PAST 6 HOURS: SOUTHEASTWARD AT 17 KTS SIGNIFICANT WAVE HEIGHT: 17 FEET SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS FLARING CONVECTION OVER AN OBSCURED LOW-LEVEL CIRCULATION CENTER (LLCC). CONVECTIVE BANDING OVER THE EASTERN SEMICIRCLE HAS BECOME MORE FRAGMENTED OVER THE PAST SIX HOURS. A 130802Z SSMIS 91GHZ MICROWAVE IMAGE REVEALS DEEP CONVECTIVE BANDING WRAPPING INTO A DEFINED, RAGGED LLCC WITH SHALLOW BANDING EXPOSED OVER THE WESTERN SEMICIRCLE. THIS RECENT DETERIORATION IS LIKELY DUE TO PERSISTENT WESTERLY VERTICAL WIND SHEAR AND MID- TO UPPER-LEVEL DRY AIR ENTRAINMENT. THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON A 131024Z ASCAT-B BULLSEYE IMAGE, WHICH SHOWS 45-50 KNOT WINDS. THE INITIAL INTENSITY OF 65 KTS IS ASSESSED WITH MEDIUM CONFIDENCE BASED ON DVORAK CURRENT INTENSITY ESTIMATES, HOWEVER, DATA T ESTIMATES HAVE DECREASED STEADILY TO T3.0-3.5 (45-55 KNOTS). INITIAL WIND RADII BASIS: SCATTEROMETER DATA CURRENT STEERING MECHANISM: DEEP-LAYERED SUBTROPICAL RIDGE (STR) POSITIONED TO THE EAST. AGENCY DVORAK AND AUTOMATED FIXES: PGTW: 4.0 - 65 KTS KNES: 4.0 - 65 KTS CIMSS SATCON: 69 KTS AT 132307Z CIMSS ADT: 82 KTS AT 130840Z FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE VWS: 10-15 KTS SST: 28-29 CELSIUS OUTFLOW: STRONG POLEWARD OTHER FACTORS: DRY AIR ENTRAINMENT 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 03P WILL TRACK EAST-SOUTHEASTWARD TO SOUTHEASTWARD THROUGH THE FORECAST PERIOD ALONG THE SOUTHWESTERN PERIPHERY OF A DEEP-LAYERED STR. HOWEVER, THE SYSTEM WILL ACCELERATE AFTER TAU 12 WITHIN ENHANCED FLOW BETWEEN THE AFOREMENTIONED STR AND A DEEP, HIGH AMPLITUDE TROUGH. THIS STEERING PATTERN IS CLASSIFIED AS A HIGH AMPLITUDE PATTERN AND IS COMMON EAST OF AUSTRALIA, AND GENERALLY PRODUCES FASTER-THAN-CLIMATOLOGICAL TRACK SPEEDS WITH HIGH CONFIDENCE TRACK CONFIDENCE. TC 03P WILL RE- INTENSIFY BY TAU 12 TO A PEAK INTENSITY OF 70 KNOTS. BY TAU 36, THE SYSTEM WILL BEGIN TO INTERACT WITH THE SUBTROPICAL WESTERLIES AND TRACK OVER COOLER SST (25C). BY TAU 72, TC 03P WILL ENCOUNTER STRONG VERTICAL WIND SHEAR (35-50 KNOTS) WITH SIGNIFICANTLY COOLER SST (22- 19C). THIS WILL SERVE TO RAPIDLY WEAKEN THE CONVECTIVE STRUCTURE AND LEAD TO SUBTROPICAL TRANSITION. HOWEVER, THE SYSTEM WILL REMAIN A STORM-FORCE SUBTROPICAL LOW AS IT APPROACHES NEW ZEALAND. MODEL DISCUSSION: AS MENTIONED EARLIER, THE HIGH AMPLITUDE PATTERN TYPICALLY PRODUCES TIGHTLY-GROUPED FORECAST GUIDANCE AND, CONSEQUENTLY, HIGH CONFIDENCE FORECAST TRACKS. THIS SYSTEM IS NO EXCEPTION WITH A 70-80NM SPREAD IN SOLUTIONS THROUGH 48. ADDITIONALLY, THE 130000Z ECMWF ENSEMBLE (EPS) ALSO INDICATES A TIGHT GROUPING OF ENSEMBLE MEMBERS AND A NARROW CONE OF HIGH STRIKE PROBABILITY OVER AND JUST NORTH OF NEW CALEDONIA EXTENDING SOUTHEASTWARD. THE JTWC INTENSITY FORECAST IS MORE UNCERTAIN WITH RELIABLE INTENSITY GUIDANCE RANGING FROM 50-70 KNOTS WITHIN THE NEXT 24 HOURS. AFTER TAU 48, THE INTENSITY GUIDANCE COMES INTO BETTER ALIGNMENT WITH A STEADY WEAKENING TREND THROUGH TAU 72. THE JTWC INTENSITY FORECAST IS CONSERVATIVELY PLACED CLOSER TO THE HWRF WITH A SLIGHT INTENSIFICATION EXPECTED OVER THE NEXT 12 HOURS. FORECAST CONFIDENCE: TRACK 0 - 72 HR: HIGH INTENSITY 0 - 72 HR: MEDIUM// NNNN