WDPS31 PGTW 080300 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 07P (SEVEN) WARNING NR 006// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. SUMMARY: INITIAL POSITION: 24.4S 165.6E INITIAL INTENSITY: 40 KTS GEOGRAPHIC REFERENCE: 141 NM SOUTH OF NOUMEA, NEW CALEDONIA MOVEMENT PAST 6 HOURS: EAST-SOUTHEASTWARD AT 29 KTS SIGNIFICANT WAVE HEIGHT: 20 FEET SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) INDICATES THAT TC 07P IS RAPIDLY FALLING APART, BECOMING DECAPITATED AND STARTING TO FEEL THE EFFECTS OF DRY, CONVERGENT FLOW MOVING IN FROM THE WEST. ANIMATED MSI SUGGESTS THAT THE VORTEX IS IN THE PROCESS OF DECOUPLING AND ELONGATING, THOUGH A DISCREET LOW LEVEL CIRCULATION CENTER (LLCC) REMAINS ELUSIVE DUE TO MASKING BY UPPER-LEVEL CIRRUS BLOWOFF. THE INITIAL POSITION IS THUS ASSESSED WITH MEDIUM CONFIDENCE, DUE TO THE ELONGATION AND OBSCURATION OF THE LLCC. AGENCY DVORAK CURRENT INTENSITIES (CI) REMAIN AT T3.0 (45 KNOTS) BUT THE DATA-T NUMBERS ARE COMING DOWN TO 2.5 AT BEST. SIMILARLY, THE ADT CI IS T2.8 BUT THE RAW-T VALUES ARE DOWN TO 2.5. THE DMN AND OPEN-AIIR ARE BOTH DOWN AROUND 35 KNOTS AS WELL, ALL OF WHICH SUPPORTS A 35-40 KNOT INTENSITY AT THIS POINT. THE INITIAL INTENSITY OF 40 KNOTS IS THUS ASSESSED WITH MEDIUM CONFIDENCE. ANALYSIS INDICATES A MARGINAL ENVIRONMENT AT BEST, RAPIDLY TRENDING TOWARDS UNFAVORABLE. SSTS ARE NOW AROUND 25C AND WILL CONTINUE TO DECREASE AS THE SYSTEM MOVES SOUTHWARD. SHEAR IS NOW APPROACHING 30 KNOTS AND A STRONG UPPER-LEVEL TROUGH TO THE WEST IS USHERING IN CONVERGENT FLOW AND DRY AIR ON THE WESTERN PERIPHERY OF THE SYSTEM. INITIAL WIND RADII BASIS: PERSISTENCE CURRENT STEERING MECHANISM: SOUTHWEST PERIPHERY OF A DEEP-LAYER SUBTROPICAL RIDGE (STR) CENTERED TO THE NORTHEAST. AGENCY DVORAK AND AUTOMATED FIXES: PGTW: T3.0 - 45 KTS KNES: T3.0 - 45 KTS NFFN: T3.0 - 45 KTS CIMSS ADT: 41 KTS AT 072330Z FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINAL VWS: 25-30 KTS SST: 25-26 CELSIUS OUTFLOW: STRONG POLEWARD OTHER FACTORS: CONVERGENT FLOW AND DRY AIR MOVING IN FROM THE WEST. ANALYSIS CONFIDENCE: INITIAL POSITION: MEDIUM INITIAL INTENSITY: MEDIUM INITIAL WIND RADII: LOW 3. FORECAST REASONING. SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO THE FORECAST FROM THE PREVIOUS WARNING. FORECAST DISCUSSION: ITS GLORY DAYS NOW LAYING IN ITS WAKE, TC 07P HAS COMMENCED WEAKENING, WHILE ALSO BEGINNING SUBTROPICAL TRANSITION (STT). SHEAR, ALREADY APPROACHING 30 KNOTS, IS FORECAST TO CONTINUE TO INCREASE AND WILL ONLY SERVE TO ACCELERATE THE DECAPITATION OF THE SYSTEM OVER THE NEXT 24 HOURS. AT THE SAME TIME, VERY DRY MID-LEVEL AIR WILL CONTINUE TO RAPIDLY MOVE IN FROM THE WEST AND WILL COMPLETELY SMOTHER THE SYSTEM OVER THE NEXT DAY. BY TAU 24, THE LLCC WILL BE FULLY EXPOSED AND DEVOID OF SIGNIFICANT CONVECTION AND WILL RAPIDLY WEAKEN TO BELOW WARNING CRITERIA NO LATER THAN TAU 24. THE SYSTEM IS ALREADY STARTING STT AND ACCELERATION OF THIS PROCESS IS EXPECTED GOING FORWARD WITH TRANSITION TO A FULLY SUBTROPICAL LOW PRESSURE AREA ANTICIPATED NO LATER THAN TAU 24. MODEL DISCUSSION: TRACK GUIDANCE IS IN GOOD AGREEMENT THROUGH THE SHORT DURATION OF THE FORECAST PERIOD, WITH ALL CONSENSUS MEMBERS CONSTRAINED IN A TIGHTLY PACKED ENVELOPE CONSISTENT WITH THE JTWC FORECAST. THE JTWC FORECAST IS CONSISTENT WITH THE BULK OF THE INTENSITY GUIDANCE, WHICH WEAKENS THE SYSTEM BELOW 35 KNOTS BY TAU 24. HOWEVER, THE NAVGEM VERSION OF COAMPS-TC AND THE HWRF BOTTOM OUT AT 35 KNOTS AND THEN REINTENSIFY THE SYSTEM THEREAFTER AS IT UNDERGOES EXTRA-TROPICAL TRANSITION (ETT) AFTER THE END OF THE CURRENT FORECAST PERIOD. CONFIDENCE IN THE TRACK AND INTENSITY FORECAST IS HIGH. FORECAST CONFIDENCE: TRACK 0 - 72 HR: HIGH INTENSITY 0 - 72 HR: HIGH// NNNN