WDPS32 PGTW 011500 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 09P (NINE) WARNING NR 004// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. SUMMARY: INITIAL POSITION: 15.4S 153.9E INITIAL INTENSITY: 35 KTS GEOGRAPHIC REFERENCE: 475 NM EAST OF CAIRNS, AUSTRALIA MOVEMENT PAST 6 HOURS: EAST-SOUTHEASTWARD AT 07 KTS SIGNIFICANT WAVE HEIGHT: 12 FEET SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY INDICATES AN INCREASINGLY DISORGANIZED SYSTEM WITH ERODING DEEP CONVECTION AND A WEAKLY DEFINED LOW-LEVEL CIRCULATION (LLC). A 010840Z SSMIS 91GHZ COLOR COMPOSITE MICROWAVE IMAGE REVEALED A BROAD LLC WITH A LINE OF DEEP CONVECTION TO THE NORTHWEST. TC 09P IS LOCATED JUST EAST OF AN UPPER-LEVEL POINT SOURCE WITH DIVERGENT FLOW ALONG A WEST-NORTHWEST TO EAST-SOUTHEAST AXIS, HOWEVER, CONVERGENT FLOW SOUTH OF THE SYSTEM IS RESTRICTING POLEWARD OUTFLOW. ADDITIONALLY, THERE IS SIGNIFICANT DRY AIR PRESENT OVER THE SOUTHERN PERIPHERY OF THE SYSTEM WITH MID-LEVEL DRY AIR ENTRAINMENT. SEA SURFACE TEMPERATURES (29-30C) AND VERTICAL WIND SHEAR REMAIN FAVORABLE. THE INITIAL POSITION IS PLACED WITH LOW CONFIDENCE BASED ON THE EIR AND SSMIS IMAGE. THE INITIAL INTENSITY OF 35 KTS IS ASSESSED WITH MEDIUM CONFIDENCE BASED ON THE PGTW CURRENT INTENSITY ESTIMATE OF 2.5 (35 KNOTS). INITIAL WIND RADII BASIS: PERSISTENCE CURRENT STEERING MECHANISM: NEAR-EQUATORIAL RIDGE (NER) POSITIONED TO THE NORTH AND NORTHEAST. AGENCY DVORAK AND AUTOMATED FIXES: PGTW: T2.5 - 35 KTS KNES: T2.0 - 30 KTS ABRF: T2.0 - 30 KTS CIMSS ADT: 45 KTS AT 011140Z FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE VWS: 5-10 KTS SST: 29-30 CELSIUS OUTFLOW: WEAK POLEWARD AND EQUATORWARD OTHER FACTORS: DRY AIR ENTRAINMENT ANALYSIS CONFIDENCE: INITIAL POSITION: LOW INITIAL INTENSITY: MEDIUM INITIAL WIND RADII: MEDIUM 3. FORECAST REASONING. SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO THE FORECAST FROM THE PREVIOUS WARNING. FORECAST DISCUSSION: TC 09P IS FORECAST TO TRACK EASTWARD TO EAST-SOUTHEASTWARD UNDER THE STEERING INFLUENCE OF THE NER THROUGH TAU 72. TC 09P WILL MAINTAIN INTENSITY AT 35 KNOTS THROUGH TAU 36 DUE TO DRY AIR ENTRAINMENT AS WELL AS INCREASING MID-LEVEL VERTICAL WIND SHEAR (VWS). AFTER TAU 36, THE SYSTEM WILL INTENSIFY SLOWLY AS VWS DECREASES, THE CORE ENVIRONMENT MOISTENS AND POLEWARD OUTFLOW IMPROVES. AFTER TAU 72, TC 09P WILL GRADUALLY TURN SOUTHEASTWARD ALONG THE WESTERN FLANK OF A BUILDING SUBTROPICAL RIDGE (STR) TO THE EAST. TRACK SPEEDS WILL INCREASE AFTER TAU 72 AS THE SYSTEM TRACKS WITHIN THE ENHANCED FLOW BETWEEN THE STR AND A BROAD MIDLATITUDE TROUGH. THE SYSTEM WILL PEAK AT 55 KNOTS BY TAU 96 THEN WEAKEN SLIGHTLY, HOWEVER, THIS PORTION OF THE INTENSITY FORECAST IS UNCERTAIN DUE TO POSSIBLE DRY AIR ENTRAINMENT AND SLIGHTLY COOLER SEA SURFACE TEMPERATURES (27-28C). MODEL DISCUSSION: NUMERICAL MODELS ARE IN FAIR AGREEMENT WITH A 220NM SPREAD IN SOLUTIONS AT TAU 72. HOWEVER, THERE IS LARGE SPREAD AFTER TAU 72. THE BULK OF THE GUIDANCE TURNS THE SYSTEM SOUTHEASTWARD TO SOUTHWARD OVER AND JUST NORTH OF NEW CALEDONIA. THE 010600Z ECMWF (EPS) ENSEMBLE STRIKE PROBABILITY GRAPHIC INDICATES A MORE PROLONGED EAST-SOUTHEASTWARD TRACK THEN A SHARP SOUTHWARD TRACK. BASED ON THE POSITIONAL UNCERTAINTY AND SPREAD IN MODEL TRACKERS, THERE IS MEDIUM CONFIDENCE IN THE JTWC TRACK FORECAST. FORECAST CONFIDENCE: TRACK 0 - 72 HR: MEDIUM TRACK 72-120 HR: MEDIUM INTENSITY 0 - 72 HR: MEDIUM INTENSITY 72-120 HR: MEDIUM// NNNN