WTPS32 PGTW 150900 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/TROPICAL CYCLONE 06P (ZAZU) WARNING NR 008// RMKS/ 1. TROPICAL CYCLONE 06P (ZAZU) WARNING NR 008 02 ACTIVE TROPICAL CYCLONES IN SOUTHPAC MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE WIND RADII VALID OVER OPEN WATER ONLY --- WARNING POSITION: 150600Z --- NEAR 19.0S 173.6W MOVEMENT PAST SIX HOURS - 100 DEGREES AT 05 KTS POSITION ACCURATE TO WITHIN 060 NM POSITION BASED ON CENTER LOCATED BY A COMBINATION OF SATELLITE AND SYNOPTIC DATA PRESENT WIND DISTRIBUTION: MAX SUSTAINED WINDS - 045 KT, GUSTS 055 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 034 KT WINDS - 170 NM NORTHEAST QUADRANT 120 NM SOUTHEAST QUADRANT 075 NM SOUTHWEST QUADRANT 070 NM NORTHWEST QUADRANT REPEAT POSIT: 19.0S 173.6W --- FORECASTS: 12 HRS, VALID AT: 151800Z --- 19.6S 172.0W MAX SUSTAINED WINDS - 045 KT, GUSTS 055 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 034 KT WINDS - 180 NM NORTHEAST QUADRANT 150 NM SOUTHEAST QUADRANT 100 NM SOUTHWEST QUADRANT 120 NM NORTHWEST QUADRANT VECTOR TO 24 HR POSIT: 135 DEG/ 15 KTS --- 24 HRS, VALID AT: 160600Z --- 21.6S 169.7W MAX SUSTAINED WINDS - 045 KT, GUSTS 055 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 034 KT WINDS - 190 NM NORTHEAST QUADRANT 160 NM SOUTHEAST QUADRANT 100 NM SOUTHWEST QUADRANT 150 NM NORTHWEST QUADRANT VECTOR TO 36 HR POSIT: 145 DEG/ 19 KTS --- 36 HRS, VALID AT: 161800Z --- 24.6S 167.2W MAX SUSTAINED WINDS - 040 KT, GUSTS 050 KT WIND RADII VALID OVER OPEN WATER ONLY BECOMING EXTRATROPICAL RADIUS OF 034 KT WINDS - 210 NM NORTHEAST QUADRANT 170 NM SOUTHEAST QUADRANT 140 NM SOUTHWEST QUADRANT 140 NM NORTHWEST QUADRANT VECTOR TO 48 HR POSIT: 160 DEG/ 18 KTS --- EXTENDED OUTLOOK: 48 HRS, VALID AT: 170600Z --- 28.0S 165.7W MAX SUSTAINED WINDS - 035 KT, GUSTS 045 KT WIND RADII VALID OVER OPEN WATER ONLY EXTRATROPICAL RADIUS OF 034 KT WINDS - 220 NM NORTHEAST QUADRANT 180 NM SOUTHEAST QUADRANT 150 NM SOUTHWEST QUADRANT 120 NM NORTHWEST QUADRANT --- REMARKS: 150900Z POSITION NEAR 19.2S 173.2W. 15DEC20. TROPICAL CYCLONE 06P (ZAZU), LOCATED APPROXIMATELY 210 NM WEST OF NIUE, HAS TRACKED EASTWARD AT 05 KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A RELATIVELY COMPACT SYSTEM, WHICH IS STRUGGLING TO OFFSET INCREASING WESTERLY VERTICAL WIND SHEAR (VWS), WITH EXPOSED SPIRAL BANDS WRAPPING INTO THE OBSCURED LOW LEVEL CIRCULATION CENTER (LLCC). THE INITIAL POSITION IS PLACED WITH FAIR CONFIDENCE BASED ON EXTRAPOLATION OF A WEAK LOW-EMISSIVITY REGION EVIDENT IN A 150450Z 37GHZ MICROWAVE IMAGE AS WELL AS ANALYSIS OF SURFACE OBSERVATIONS FROM VAVA’U AND LIFUKA ISLANDS. THE INITIAL INTENSITY IS SET AT 45 KNOTS WITH HIGH CONFIDENCE BASED ON MULTI-AGENCY DVORAK CURRENT INTENSITY ESTIMATES OF T3.0 FROM BOTH PGTW AND KNES, AN ADVANCED DVORAK TECHNIQUE (ADT) ESTIMATE OF T2.9 (44 KNOTS) AND A CIMSS SATELLITE CONSENSUS ESTIMATE OF 45 KTS. TC ZAZU IS TRACKING EAST- SOUTHEAST ALONG THE WESTERN PERIPHERY OF A DEEP SUBTROPICAL RIDGE (STR) LOCATED TO THE EAST. ENVIRONMENTAL ANALYSIS REVEALS AN ENVIRONMENT UNFAVORABLE FOR ADDITIONAL DEVELOPMENT, WITH HIGH (>30 KNOTS) VWS AND LUKEWARM (26-27 DEG C) SSTS BEING SLIGHTLY OFFSET BY ROBUST POLEWARD OUTFLOW AHEAD OF AN APPROACH MID-LATITUDE TROUGH. TC 05P IS FORECAST TO TRACK EAST-SOUTHEAST THROUGH TAU 12, THEN TURN MORE SOUTHEASTWARD THROUGH THE REMAINDER OF THE FORECAST PERIOD, ALONG THE SOUTHWEST PERIPHERY OF THE DEEP-LAYER STR TO THE EAST. THE GENERAL ENVIRONMENT IS FORECAST TO BECOME INCREASINGLY HOSTILE TO TC 05P, WITH VWS FORECAST TO INCREASE TO OVER 50 KNOTS BY TAU 24. THE RELATIVELY WARM SSTS AND ROBUST POLEWARD OUTFLOW WILL OFFSET THE VWS THROUGH TAU 24, ALLOWING THE SYSTEM TO MAINTAIN INTENSITY, BUT THEREAFTER AS THE VWS OVERPOWERS THE OUTFLOW AND THE SYSTEM MOVES INTO COOLER WATERS WITH SSTS BELOW 26 DEG CELSIUS. AS TC ZAZU APPROACHES THE BAROCLINIC ZONE ASSOCIATED WITH A STRONG FRONT MOVING IN FROM THE WEST NEAR TAU 36, IT WILL BEGIN EXTRATROPICAL TRANSITION (ETT), AND IS FORECAST TO COMPLETE ETT BY TAU 48. NUMERICAL MODEL TRACK GUIDANCE IS IN GOOD AGREEMENT OVERALL, WITH ONLY 75-90 NM SPREAD AT TAU 48, LENDING HIGH CONFIDENCE IN THE JTWC FORECAST TRACK WHICH IS PLACED ALONG THE NORTHERN EDGE OF THE GUIDANCE ENVELOPE. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 150600Z IS 19 FEET. NEXT WARNINGS AT 151500Z, 152100Z, 160300Z AND 160900Z. REFER TO TROPICAL CYCLONE 05P (YASA) WARNINGS (WTPS31 PGTW) FOR SIX-HOURLY UPDATES.// NNNN